Functional Properties of Advanced Engineering Materials and Biomolecules

ZnO/bentonite hybrids were obtained by the microwave-assisted hydrothermal method, in order to change the bentonite surface and improve its activity for biodiesel production. No previous treatment of the clay was used and in situ crystallization of ZnO was done by a fast single step method. A factorial design was used to optimize synthesis conditions (e.g., reaction time, solution pH, and ZnO amount). The hybrids were fully characterized to determine its structural, chemical, and morphological properties. The results demonstrated the positive contribution of the microwave-assisted hydrothermal method to the formation of ZnO/bentonite hybrids, in addition to showing that the pH was the most important parameter influencing the formation of ZnO. A pH value of 8 favored the incorporation of approximately 19.6% of ZnO onto the smectite particles even after 5 min of microwave irradiation. The ZnO/bentonite hybrid with the biggest amount of ZnO was applied as a catalyst in the transesterification reaction of soybean oil. As such, our results demonstrated an ethyl ester conversion rate higher than 73% with better performance than that of natural bentonite (44%), which represents approximately 66% of the improvement of the catalytic activity.

We make an overview of chemical/physical computational simulation models for materials and biomolecular systems emphasizing basic philosophies, theoretical foundations and underlying limitations from Schrodinger´s equation to actual state of the art modeling as well as future trends and perspectives. We start with the ab initio models, including HF, CI, CC, MPT, MCSCF, CASSCF, MRC, offering good accuracy, whereas the need to address larger complex systems and computational limitations led to semiempirical models (ZDO, CNDO, INDO, ZINDO, NDDO, MNDO, AM1, PM3, PM6, PM7, DFTB) with inherent simplification/parametrization of integrals. Limitations of the ab initio approach and lack of accuracy for semiempirical models, when not specifically parameterized, led to density functional methods with excellent cost/performance/advantages and wide applications in both materials and biomolecular systems which resulted, however, in decades-long search for the best density functionals organized by Jacob’s ladder (LSDA, GGA, mGGA, GH, LH, RSH, DH, MCKS, PT2/RPA). Methods such as TDFT, MC, MD, MM and AIMD are summarized. Localized/all-electron/PW basis functions, OPW, APW, LMTO, LAPW, pseudopotential (PAW, NCPP, USPP) approach within the framework of DFT, Al, SE, AIMD, introduced methodologies for electronic structure/properties calculations for the solid material state which, with support of efficient, versatile computer codes, made feasible simulations of a wide range of properties in materials/biomolecular systems. We introduce recent cognitive overload addressed by sharing/feedback/free access of data/software/technical experience and discuss as well methodologies, research areas, databases of the so-called second computer revolution/fourth scientific paradigm (material learning models applied to material science). We also address Docking, Pharmacophore, Homology modeling for Biomolecular Systems as well as Coarse-Grained methodology including Force Matching, Inverse Boltzmann, Inverse Monte Carlo, Bayesian Dissipative Particle Dynamics with applications in Soft Matter, Macromolecules, Polymers, Interfacial Systems (polymer/material), Biomolecules, Water, Proteins, Carbohydrates.

Many studies have focused on understanding synthesis parameters, defects, electronic and structural properties of novel functional materials, which has proven to be extremely important for the development of new technologies. This may, in principle, provide clues to elucidate some of their design rules at the nanoscale further. However, currently, it is still virtually impossible to predict the final shape of these colloidal nanocrystals, as well as their unique properties, which in turn are strongly dependent on crystal morphologies as prepared. Hence, diverse strategies have been widely adopted to obtain novel target materials with well-defined morphologies. Among emerging materials, more recently, perovskite-like materials have gained immense attention due to their outstanding properties. In this chapter, we will present the recent progress in synthesis, theory, and characterization of perovskite-like colloidal nanocrystals for the development of advanced optoelectronic applications.

The ability to produce phase pure and compositionally controlled nanomaterials at temperatures lower than the ones required by solid state reaction methods is one of the most important features in a solution-chemistry synthetic method. The sol–gel based methods usually use many of organic compounds throughout the synthetic process, which can be detrimental to certain applications, as high quantities of residual carbon can be found along the final product. The Oxidant Peroxo Method, usually known by the acronym OPM, is a solution-chemistry method based on the production of peroxo complexes with hydrogen peroxide and different transition metal ions at alkaline pH. The production of these peroxo complexes leads to an amorphous material that upon calcination produces phase pure transition metal oxides with controlled composition. One special feature of the OPM method is the total absence of the organic compounds during the synthesis, which avoids the presence of undesired pyrolyzed organic molecules mixed with the metal oxide product. Additionally, the absence of organic compounds produces an oxidizing atmosphere during the synthesis, yielding very reactive powders, facilitating the production highly dense ceramic pellets for electronic applications. The production of powders with surface containing peroxo groups, also, has been beneficial for increasing the photocatalytic activity of titanium-based compounds and for use as a precursor in the solid-state reactions, which considerably decreases the processing temperature. Since its inception and first publication, back in 2001, the OPM method has been successfully applied by different research groups worldwide to produce binary oxides, i.e. TiO₂, tertiary oxides, PbTiO₃, BaZrO₃, and doped tertiary oxides Pb_1−xLaTiO₃. The variety of different metal oxides produced confirms the versatility of OPM method on yielding not only different compositions, but also different crystalline structures, like anatase, perovskite, sillenite, and spinel. Furthermore, the OPM method has yield metal oxides for many different applications, such as dielectric, optical, and photocatalytic. For instance, undoped Bi₁₂TiO₂₀ and Nb-doped Bi₁₂(Ti_1−xNb_x)O₂₀ were used as efficient photocatalysts for degradation of rhodamine B under ultraviolet and visible lights, presenting better activity than TiO₂. In this chapter, the chemistry underlying the OPM method and the oxides most commonly prepared by this technique will be described, focusing how the method contributed to the advance of the synthetic, structural, and application aspects related to each one of these compounds. The future goals and applications of the method will be critically discussed. The authors hope this chapter can provide enough information to motivate a continuous dissemination of the OPM method, in view of its confirmed successful features and potential.

Alkaline earth stannates with perovskite structure (ASnO_3, A = Ca, Sr, Ba) have been studied for a long time due to their unique structure and physicochemical properties, but few works in literature have been devoted to their thin films. The technology of thin films makes structuring materials in fettered dimensions very simple, making them useful in electronic devices. Moreover, the possibility of oriented and epitaxial growth allows a better understanding of the surface and interface properties of the films to tailor their functionalities. In this chapter, recent findings on photoluminescent properties of ASnO₃-type perovskites are discussed and results on polycrystalline and epitaxial thin films deposited using a physical deposition method (pulsed laser deposition, PLD) and a chemical one (chemical solution deposition, CSD) are presented. In this context, two different series were carefully investigated considering the Sr-site substitution in SrSnO₃ perovskite to form the Ca_1−xSr_xSnO₃ solid solution, and the Sn-site substitution giving origin to SrSn_1−xTi_xO₃ (x = 0, 0.25, 0.5, 0.75 and 1). The structural and microstructural characteristics of all films are first presented. Then, discussion about the influence of composition, method of deposition, type of growth and short-range order/disorder related to photoluminescence properties are shown.

Since the industrial revolution from century XIX, the global environment has received a charge of each more pollutant. Even with filters and catalysts to minimize some industrial residues is necessary more caution and research treat waste and other products. In such a perspective, water clean and environmental remediation are some of the most important themes for humanity. The chemical treatment for a large quantity of generated pollutant residues by industry is a great challenge. Such pollutants are in molecules or materials forms. In particular, a molecule group denominated dyes is the focus. Heterogeneous catalysis based on semiconductor oxides is a widely investigated topic as a broad and potential technology for clean water treatment. Then, we present a chapter with a comprehensive perspective of the modifications applied in CuO and ZnO to improve the efficiency in heterogeneous photocatalysis processes. The DFT approaches ally to experimental evidence showed that doping and heterojunctions are efficient tools to maximize the discovery of the advanced materials directed to water clean and environmental remediation. Mn-doped ZnO presented an exciting performance for photocatalysis on methylene blue dye from defects connected to intermediary electronic levels. Heterojunction made from CuO/ZnO is a putative candidate for photodegradation in two ways: (i) generation in situ of oxidizing molecules; and (ii) the sunlight wavelength range as an energy source. Such molecular mechanism is possible from the generation, stability, and control on the charges carriers diffusion inside semiconductor oxides. How to understand and influence the creation of the electron–hole pair is the fundamental step to establish the heterogeneous photocatalysis based on semiconductor oxides as one of the essential applications of the advanced materials in environmental remediation.

It is well-known that information technology has been the base of our modern society. For this reason, semiconductor materials are extremely important and have a pivotal role in many technologies. Since the fantastic discovery of graphene in 2004 and the subsequent Nobel Prize for its fascinating two-dimensional (2D) properties, so far, a plethora of atomically thin 2D-layered materials and Van der Waals heterostructures has been discovered with rich material platforms; all the way from metallic (graphene, TaSe₂), semiconducting (WSe₂, MoS₂), superconducting (NbSe₂, FeSe) to topological insulators (Bi₂Se₃, Sb₂Te₃). These artificially created atomically well-controlled low dimensional electronic systems cover several exciting phenomena in the field of condensed matter physics (e.g., such as magnetism, superconductivity, topological insulation, and so on). In contrast to its 3D counterparts, these materials become strongly renormalized in the strict 2D limit, through a combination of quantum confinement and enhanced electronic interactions. As a result, these fascinating compounds exhibit enhanced quantum effects and display robust interactions with electromagnetic fields. In this chapter, several state-of-the-art fabrication methods, both top-down (such as molecular beam epitaxy, metal–organic chemical vapor deposition, mechanical exfoliation) and bottom-up (colloidal, vertical stacking, ligand displacement, etc.) will be introduced. Combining different electrical, optical and thermal measurements, the strategic characterization of complex electronic states down to atomic scales will be discussed. Finally, some of the recently studied as well as prospective applications of these constantly emerging smart materials in the field of health (bioelectronics, wearable sensors) and energy (photovoltaics, optoelectronics) industries will be further discussed.

The development of society is dependent on commodities such as fuels and chemical feedstock. Most of these commodities are obtained from oil as raw material. Although the need to find a friendly solution to couple an economically viable energy model with a greener solution, it is known that technologies applying renewable sources are in an early stage of development. The conversion of methane into clean fuels or chemical feedstock with high commercial value, such as hydrogen, ethylene, or methanol is interesting from the energetic and economic point-of-view. Among the methods of methane conversion, the industrially used is the steam reforming (MSR), in which methane reacts with water to produce syngas, a mixture of CO and H₂. Nevertheless, this reaction is highly endothermic and responsible for a large volume of CO₂ emitted by the reactor burners that provide energy to the reactors. An interesting alternative process for methane conversion is the dry reforming of methane (DRM), which consists of the reaction of methane with CO₂, also yielding syngas. The advantage of this reaction is the utilization of two harmful gases to the atmosphere. The disadvantage of this reaction is due to the catalyst deactivation by carbon deposition. In heterogeneous catalysis, there is a strong relationship between catalytic performance and surface and textural properties, that are outlined by the number and distribution of available active sites. In this way, different synthetic routes may be used to design these properties and obtain products of commercial interest, such as ethylene. The commercial production of ethylene occurs by the recuperation of refinery gases, thermal cracking of light hydrocarbons, mainly ethane and propane, or a combination of both processes. An alternative process of ethylene production may be from natural gas and or biogas. This process can be performed by the syngas route or by oxidative coupling of methane (OCM). The first process is an indirect conversion of methane and involves several steps, which increases the process costs. The second one is a direct conversion, where methane is directly converted into C₂ (ethane and ethylene) hydrocarbons. Although the OCM is not yet a reaction on an industrial scale, several efforts are being made to design a catalytic system to achieve C₂ hydrocarbons yields above 30%, the minimum required. Besides that, another technology has been studied to directly produce ethylene via the oxidative coupling of methane using CO₂ as a mild oxidant (CO₂-OCM). These technological routes for the valorization of methane and CO₂ will be addressed in this review.

The sun is a renewable and widely available energy source, but it needs to be converted into other types of energy to be useful. Conversion of solar energy directly to electrical energy can be done using photovoltaic cells, but solar intermittency becomes a problem in the generation of electrical energy continuously. Thus, technologies for the storage of solar energy need to be developed to make the best use of this energy source. Water splitting photoelectrochemical cells are devices that can store solar energy into chemical energy. They are formed by a photo(anode) and a photo(cathode) that can collect solar energy and carry out oxidation and reduction of water, forming O₂ in the anode and H₂ in the cathode, thus storing solar energy in the chemical bonds of the H2 molecule. In recent years, many light-collecting materials have been tested as photoanodes and photocathodes in photoelectrochemical cells. Among photoanodes, BiVO₄ has been widely used due to its moderate bandgap energy (2.4 eV), the valence band energy level suitable for water oxidation, and its theoretical solar energy conversion capacity of approximately 10%. Among photocathodes, CuBi₂O₄ is a promising semiconductor for use in PEC cells due to its small bandgap energy (1.8 V) and exceptionally large onset potential (> 1 V versus RHE) which makes it an excellent semiconductor to be coupled with wide bandgap photoanodes. Therefore, in this review, we examine the most current strategies used to improve the optical, electronic, and surface properties of BiVO₄ and CuBi₂O_4, including doping, heterojunction, passivation, and the use of catalysts for the oxygen and hydrogen evolution from water.

Photodynamic Therapy (PDT) is a medical modality that has been applied against several types of cancer, macular degeneration, pointed condyloma, actinic keratosis as well as infections caused by fungi, viruses, and bacteria. When PDT is applied against microorganisms, the technique is called as antimicrobial photodynamic therapy (aPDT). PDT/aPDT principle involves the association of a light source (performed by a LASER, LED, and optical fiber), a non-toxic photosensitizer (PS), and molecular oxygen dissolved in the tissue of interest. The photosensitizer is excited by a light source of a specific wavelength which, in the presence of oxygen, generate high-cytotoxic reactive oxygen species (ROS) as well as superoxide anion (O₂^·−), hydroxyl radical (HO^·), hydrogen peroxide (H₂O₂) and singlet oxygen (¹O₂). These species cause damage to tumor cells and vasculatures by apoptosis, necrosis, and activating the immune responses. Among the main advantages of PDT is the specificity. This is guaranteed by the preferential accumulation of the photosensitizer in the cells of interest and the targeting of the lighting system without compromising healthy tissues. Additionally, it is a cheaper and less invasive than most known treatment, such as surgery, chemotherapy, and radiotherapy. Several classes of photosensitizers have been proposed for application in PDT treatment. It is necessary to mention phthalocyanines, porphyrins, bacteriochlorins, chlorines, chlorophyll-based compounds, phenothiazinium salts, and xanthene dyes. Generally, better PS compounds are hydrophobic once they accumulate in the interest tumors most effectively. However, the direct application of these in the body is harmful once PS can precipitate in the body, forming aggregates. Additionally, the pre-solubilization in an organic solvent before the application is not recommended once these are high toxicity in the cell. In this way, strategies have been proposed to solubilize hydrophobic PS in aqueous solutions and increase their biocompatibility. One of the most successful is the incorporation of PS in nanocarrier systems such as liposomes, copolymeric micelles, cyclodextrins, gold nanoparticles, microemulsions, self-assembled peptide-based nanomaterials, and others. Each nanocarrier has this specificity in order of its vantages and advantages. The main objective of this chapter is the description of PDT principles and understands more about formulations that have been used for PDT treatment.

In the last decades, the development of new technologies is strongly related to materials development, mainly for semiconductors and smart materials. A common property usually observed in both materials is the ferroelectricity. The ferroelectric materials are largely employed on data storage and memory devices, sensors, actuators, and others. In summary, the ferroelectricity is evidenced by a high spontaneous polarization inside the crystalline structure, which can arise from crystal modifications, such as, structural distortions, chemical bond profile, or material composition. Nowadays, the more important ferroelectric materials are the BaTiO₃, PbTiO₃, PbZr_xTi_1-xO₃ (PZT), and BiFeO₃ materials. In addition, the search for lead-free ferroelectric materials has attracted a big interest from scientists around the world aiming at environmentally friendly alternatives. As for lead-free materials as for Pb-based ferroelectric materials, several experimental approaches are widely reported. However, the investigation of this kind of material through theoretical investigation still represents a challenge. Therefore, this work presents theoretical approaches based on the Density Functional Theory (DFT) demonstrating its potential to develop advanced materials. Thereby, the theoretical methodology has successfully employed for clarification or prediction of the ferroelectric properties raised by chemical modifications or structural deformations.

In this paper, nanocrystalline spinel manganese ferrites MnFe₂O₄ (MFO) were synthesised using the co-precipitation method under different conditions and characterised by XRD, TEM, magnetic measurements and also theoretical calculations. Herein, the first-principles calculations and electron density topologic analysis at DFT level, including a comparison on the influence of relativistic effects, were carried out to obtain the geometries and the electronic parameters of the bulk and (100), (110) and (111) surfaces of the MFO structure, for the first time. The magnetisation field curves reveal a superparamagnetic behaviour for all the analysed samples. The saturation magnetisation values were determined to be 56.6, 53.3, and 54.8 emu/g at 300 K, respectively. Furthermore, the aqueous colloids were transferred to organic media to investigate the effect of particle size and aggregation degrees on the heating efficiency of the nanoparticles. Our findings demonstrate that the MFO spinel nanocrystals hold promise for innovative applications in magnetic hyperthermia.

Iron (III) oxide is a compound that appears in at least four different polymorphs: α-Fe₂O₃, β-Fe₂O₃, γ-Fe₂O_3, and ε-Fe₂O₃. However, Fe³⁺ ions are also present in another form of iron oxide: Fe₃O₄, which is an iron crystal structure with both Fe²⁺ and Fe³⁺ ions. And in its turn, Fe²⁺ ions are also present in the FeO form of iron oxide. Each of these six different structures presents distinctive physical properties and, therefore, diverse applications. The different crystalline forms of iron oxide have found fertile ground in the field of nanotechnology, and therefore, became popular among researchers who have proven a wide variety of biomedicine, electronics, construction, environmental remediation, and energy harvesting applications. In this regard, the main technological challenge is related to control of its physical characteristics such as morphology, size distribution, dispersion, crystallinity, structural defects, porosity, active area, as well as impurities. All of these influence the physical and optical properties of the synthesized material and will determine its field of application. As such, the synthesized material characteristics depend on the synthesis method employed. Thereby, in this chapter, we will cover the main characteristics of iron oxides with a focus on preparation processes, physicochemical properties, and their relationship with their main applications.

The experimental planning and design are important parts for successful performance and result analysis in a project. Both for industry and academic settings, there is the constant need to analyze the influence of many variables in the different types of responses. Traditionally, the influence of different variables in the experimental outcome has been analyzed by changing “one factor at a time”, which is usually described as univariate or OFAT approach. However, unless all variables are close to their optimum value, there is no guarantee that this approach will lead to the best optimized outcome. Additionally, the OFAT approach can lead to the implementation of an excessive number of experiments, which usually increases the expenses related to the project. Pursuing to analyze how the synergy between different variables can influence the experimental outcomes, there is the multivariate approach, where two or more variables are changed simultaneously enabling the experimentalist to analyze the beneficial or antagonistic effect of this combination of variables in the experimental outcome. Moreover, the multivariate approach may improve the chances to find the best outcome possible with the conduction of a fewer number of experiments. In this sense, this chapter introduces the concept of factorial design of experiments, a multivariate approach based on choosing two or more levels for multiple variables, calculating the effects of each variable individually and of each possible combination of variables, obtaining a model from these results, applying this model to predict untested conditions and judge the statistic significance of the model. The examples presented in the chapter will all be focused on the preparation and performance of nanomaterials. For instance, how the concentrations of different precursors can influence the particle size of colloidal silica nanoparticles. Or how different variables, such as, time, temperature and reagents concentration can influence the thickness of manganese sulfide (MnS) thin films. The chapter begins providing the definition of the basic terms underlying the factorial design, then, it presents examples from literature applying factorial designs starting with the simpler ones, such as 2³. Then, the chapter evolves presenting optimization and response surface methodologies factorial designs, for instance, central composite, Box-Behken, and Doehlert designs. Finally, the chapter presents tables with references from papers published in the period from 2015 to 2020. In each one of them, the factorial design of experiments was used for the development of functional materials applied in nanoparticles preparation, drug delivery and encapsulation, wastewater remediation, and solar cells development. With this chapter, the author hopes to introduce a powerful and underexplored statistical tool to scientists, engineers, and all practitioners of nanomaterials science. Focus will be placed on how they can benefit from the concepts and examples presented, and possibly adapt them for their own projects, instead of relying on heavy mathematical notations and calculations.

A novel computational protocol for drug discovery is presented. Pre-screening binding sites of selected targets with high accuracy and precision using different molecular docking programs is combined with a virtual drug discovery platform (VDDP) to screen a large number of small molecules. Several relevant proteins were identified as targets for this protocol. The protein coordinates were downloaded for docking studies from the RCSB PDB for each target. FBPase was used as a case study for the complete implementation of the VDDP. Compounds with high affinity predicted scores were identified and molecular dynamics studies were performed on the 10 highest scoring protein/small molecule complexes focusing on the allosteric binding sites. Studies were carried out using NAMD. Dissociation constants (Ki’s) for the protein–ligand complex were calculated throughout the NAMD runs and respective conformational changes in the FBPase binding pocket were observed. The inhibitor binding pocket was evaluated based on pocket shape and volume. Predicted interfacial structural changes produced in response to small molecule binding at two allosteric sites was generated in NAMD. Novel hydrogen bonding and hydrophobic interaction networks of residues in the 3D structures were identified to connect the active sites to the allosteric binding sites using an NAMD protocol.

The regulation of redox homeostasis and the reduction of oxidative stress is one of several strategies used in the development of anticancer drugs. Understanding from in silico studies, how a particular molecule binds to the receptor, allows the selection of promising compounds that may be used in antineoplastic pharmacotherapy. Protein–ligand coupling can use the study and relationship between the protein–ligand complex or that is the origin of the ligand-target interaction. The docking algorithms used present a high complexity; however, currently, the systems used to perform such studies present a friendly interface. A comparative study of various coupling algorithms can provide us with useful information to select the appropriate algorithm for drug research, design, and selection using new computational techniques. Hence, from this perspective, the purpose of this chapter is to provide new information about how it is possible to study via docking molecular Reactive Oxygen Species (ROS) enzymes against antineoplastic agents and to associate them with antitumor pharmacotherapy. The performed molecular docking results will be shown both the lower binding affinity (∆G) values for the receptor-ligand, as well as interactions in the two enzymes, obtained after validation of the molecular docking protocols for the receptors: cytochrome P450 (CYP450) and NADPH oxidase (NOX).

Fluorescent probes are powerful tools with vast potential for application in chemical biology. The specific characteristics of the main group of fluorophores coupled with the development of new techniques, have boosted their investigation in various research areas. For instance, the necessity of fluorescent tags applicable in different studies of subcellular localization and mechanisms of action of bioactive compounds has increased the development of fluorophores and new synthetic protocols toward the application in medicinal chemistry. This chapter discuss the first syntheses as well as modern synthetic methods, and some biological applications of the main fluorescent probes for drug discovery.

Tuberculosis (TB) is a serious infectious disease of chronic evolution caused by Mycobacterium tuberculosis (MTB). In general, TB control depends on many factors, among which a fast and accurate diagnosis is essential, which in turn makes it possible to carry out a complete treatment involving the proper administration of medications by patients with active disease, that is, to prevent the transmission and evolution of this disease. Despite efforts to TB control, only in 2018, about 1.5 million people died for causes attributed to TB. This likely is due to the appearance of multidrug-resistant strains to known drugs, as well as individuals with HIV/AIDS who are more susceptible to TB. Thus, in this perspective, it is fundamentally important to develop new therapeutic options for the treatment of TB. Hence, this chapter aims to identify new therapeutic alternatives available in the scientific literature based on the use of functional nanoscale materials as strategies to control the increase in bacterial resistance to drugs commonly used in the treatment of TB.

Parkinson’s Disease (PD) is a neurodegenerative disease that causes damage to the cognitive and motor system due to the death of dopaminergic neurons, which are responsible for the synthesis of the neurotransmitter dopamine. The study aimed to compare the monoamine oxidase B (MAO-B) inhibitory activity of natural molecules described in the literature with Selegiline, as potential drugs for the treatment of PD through molecular modeling, molecular docking and prediction of ADME/Tox properties. Thus, it was found the structure of the four natural molecules, Amburoside A, Harman, Harmaline and Harmalol, showed antiparkinsonian biological activity. Maps Electrostatic Potential showed similar regions between the molecules, except for Amburoside A, and Harmaline had a greater similarity in the positive potential with Selegiline. Molecular docking demonstrated that the studied molecules interact with 4–6 amino acids from the active site of the MAO-B enzyme, indicating that it has an inhibitory action on the enzyme, through hydrogen bonding and hydrophobic interactions. For ADME property predictions, most of the molecules showed good human oral absorption, all showed average permeability in Caco-2 cells, most showed average permeability in MDCK cells, showed low binding to plasma proteins, and for permeability in the blood-brain barrier, they were between good and medium. Overall, Harmaline has more properties similar to Selegiline. For toxicological properties, all molecules including Selegiline showed a positive result for the possibility of mutagenicity, whereas for the parameter of carcinogenicity in rats only the molecules Harmaline and Harmalol were positive, but no molecule was positive for carcinogenicity in mice. Therefore, the molecule that presented the best results was Harmaline, opening perspectives for the execution of in vitro studies.

Acetylcholinesterase (AChE) is a serine protease, responsible for finalising the transmission of nerve impulses at cholinergic synapses by hydrolysis of the acetylcholine (ACh) neurotransmitter. Therefore, from this perspective, it is well-known that the irreversible or prolonged inhibition of AChE elevates the synaptic Ach level, resulting in severe central and peripheral adverse effects that fall under the cholinergic syndrome spectra. Certain AChE inhibitors (AChEI) with reactivator effects stand out more specifically to combat the possible toxic effects, such as denominated oximes that are widely designed substances. Current investigations focus on searching for new and more effective broad-spectrum reactivators of the inhibited AChE (same in its aged form) against diverse organophosphorus agents. Thus, the objective of this chapter is to present a more complete understanding of new therapeutic strategies targeting AChE and its remediation processes. Through the bioremediation techniques employing degrading enzymes also show advances as a promising approach of degrading toxic organophosphorus compounds, that is, preventing the individuals from undergoing the toxic effects of the AChE inhibition. It is also important to mention that AChE is a significant therapeutic target for the treatment of certain disorders, particularly neurodegenerative diseases, such as Alzheimer’s disease. The employment of nanotechnology and biosensors represents a promising alternative, with the potential to boost the forms of treatment and diagnosis.

Toxicity assessment is an essential step in the development of drugs, agrochemicals and other bioactive substances. In silico toxicity prediction, or computational toxicology, has been growing fast during the last years mainly due to advantageous cost and labor reduction, and avoidance of experiments using animals. Considering the vast number of software available for toxicity prediction, one should be aware to pick up the right software for the right task. Herein, we aim to describe the main software as well as corresponding methodologies behind them, that are able to provide reliable and accurate results for diverse toxicological endpoints. We give special emphasis to software based on quantitative structure–activity relationships, expert systems and machine learning methodologies. With this in mind, we hope that this chapter content may serve as a valuable guide to select toxicity prediction software, and also to reinforce their usefulness towards researches concerning the development of bioactive substances.

hnRNP K is an important constitutive protein in which is found in the nucleus, cytoplasm, and mitochondria of cells. As such, this protein interacts in turn with various molecules, which are directly involved in gene expression as well as signal transduction. However, it is well-known that its aberrant expression is related to the development of most commonly diagnosed cancers, including prostate, lung, breast, and colorectal. Hence, the binding to nucleotides is the main molecular event responsible for triggers the biological activity of hnRNP K and in which is mediated by its K homology (KH) domains. Using the structure of KH3 domain, virtual screening simulations were then performed by docking using GOLD software to select small molecules that could compete with nucleotides by the binding site of the domain, intending to block the protein activity and discover new lead compounds against cancer. In vitro assays revealed the discovery of a benzimidazole and a phenylbenzamide derivative able to prevent DNA binding to hnRNP K. The molecular interaction fields computed for hydrophobic and polar interactions for KH3 structure and molecular dynamics simulations with docked compounds revealed energetically viable binding modes for these derivatives, where arginine protein residues should play a central role in molecular recognition. The design of benzimidazole and phenylbenzamide derivatives enriches the knowledge of lead compounds in the search for a novel class of anticancer drugs able to down-regulate hnRNP K.

New innovative technologies are required today for lowering the production costs of highly demanded microbial exopolysaccharides (EPS). The physiological “stress” caused by the presence of alkaline and non-cationic surfactants (Triton X-100) in the media (alone or in combination) may significantly increase Xanthomonas campestris and Enterobacter sp. Production of EPS. A mineral media (MSM) was supplemented with sucrose and crude glycerin (GB) and prepared with produced water either diluted (PW) or dialyzed (DPW) for removing mineral salts. Under conditions of alkaline stress (pH 9.5), the microbial population of X. campestris showed an increase in EPS production of 16.7% (p < 0.01). The addition of Triton X-100, however, increased the production and also the viscosity of the X. campestris EPS. On the other hand, this former substance was toxic to Enterobacter sp. in the lowest concentration tested (0.1%). The association of alkaline stress with Triton X-100 increased the production and quality of the EPS produced by X. campestris, with maximum values of 88.72% of production and 190.35% of viscosity in the medium prepared with DPW (P < 0.0001). The technology developed “surfactant/alkali stress” is an innovative way of reducing production costs and increasing the quality of EPS xanthan gum.

Chalcones derivatives compounds possess several biological activities. 08 molecules were selected from the literature. PASS Server was used to predict biological activities of chalcones (1–4) and dihydrochalcones (5–8). Pharmacokinetic and toxicological properties (ADME/Tox) of chalcones derivatives were calculated via preADMET Server. We investigated the interaction mode of selected compounds against GABA aminotransferase (GABA-AT) -PDB code 4Y0I- target indicated by PASS, using GOLD program in our molecular docking study. Our analysis was based on the interactions with Glu270, Arg445, Lys329, and Arg192 present in the active site, and indicated compounds 2, 5, and 6 as the most promising inhibitors. Molecular dynamics (MD) simulations were carried out via Biovia Discovery Studio software, based on the CHARMm force-field engine, using as input top-ranked docking poses obtained for the selected 2, 5, and 6, regarding the same crystallographic GABA-AT enzyme structure. Our results showed these compounds could bind strongly to plasma proteins, with a variation in the range of 90.21% to 100%. Compound 5 exhibited C_Brain/C_Blood = 1.07505 considered active in the CNS, while compounds 2 and 6 showed low values 0.34815 and 0.28086, respectively, therefore regarded as inactive. Analyses of RMSDs obtained for such three chalcones reveal a higher stabilization for the complex GABA-AT enzyme-chalcone 6, since a lower fluctuation of RMSD values is for it observed (from 4.0 to 7.0 Ǻ), in comparison with the values obtained for GABA-AT enzyme-chalcone 2 (RMSD from 2.5 to 8.5 Ǻ, the less stable) and GABA-AT enzyme-chalcone 5 (RMSD from 2.5 to 7.0).

Zika virus (ZIKV) is a Flavivirus belonging to the Flaviviridae family transmitted by an infected Aedes aegypti mosquito’s bite. Although it is not a highly lethal infection; however, it is associated with several morbidities such as damage to the testicles, eye damage, Guillain–Barre syndrome, fetal microcephaly, and other severe neurological complications. Due to the complications associated with the ZIKV infection and because it is also transmitted through sexual, blood, and perinatal routes, this disease becomes a serious public health problem. Since there are still no effective drugs and a licensed vaccine to control and combat the virus, many therapeutic resources from biodiversity have stood out searching for anti-ZIKV agents. In this context, plants are important sources of raw materials and prototypes for the synthesis of new drugs with therapeutic properties. Thus, this study brings a full review from classes of natural products such as phenolic compounds (flavonoids, phenolic acids, tannins, and quinones), alkaloids and terpenes (including triterpenes, saponins, and steroids), and plant species and their bioproducts as essential oils (mono, sesquiterpenes, and phenylpropanoids), with antiviral potential against ZIKV strains evidenced by in vitro and in vivo tests.