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Abstract
To synthesize noble metal nanomaterials in controlled sizes and dimensions, various approaches and mechanisms have been developed. The successful utilization of noble metal nanoparticles (NMNPs) relies on the availability of synthetic methods generating nanoparticles with the desired characteristics, namely high solubility in water, adequate morphology, and surface functionalities. Control over the shape and size of the nanoparticles is usually achieved through the careful selection of the experimental conditions, namely reducing agents, type and concentration of precursors, reaction time, temperature, UV light, (co)solvent, and capping agents. Depending on the reduction potentials of the metal precursor and the reducing-agent systems, reduction can occur at room temperature or at elevated temperatures. In general, citrate plays a role as a stabilizing agent with preparations of gold nanoparticles requiring relatively high temperatures due to its weak reducing strength. The use of amine–borane complexes is essential for the syntheses of monodisperse metallic nanoparticles. Upon the addition of strong reductants, such as NaBH4, metal cations are reduced rapidly, resulting in an immediate color change of the reaction mixture. Rationally designed molecular building blocks allow for the precise control of particle size and morphology of the supramolecular aggregate, and various defined structures, including spherical micelles, rodlike micelles, or vesicles. Molecules which control the overall crystal growth are known as “capping agents,” the term frequently used for specific adsorption of surface-active molecules on selective crystal planes of a particular geometry. Additives such as surfactants, polymers, foreign ions, ligands, and impurities present in the reaction medium have been observed to play important roles in controlling the morphology of particles produced. Surfactants, ligands, or polymers were commonly added as stabilizers to impart stability to nanoparticles against aggregation, since colloidal particles tend to aggregate to decrease the overall surface area and energy. In a typical liquid-phase synthesis, the nanoparticle formation process undergoes three distinct stages as follows: (1) reduction and generation of active nuclei; (2) formation of seed particles upon collision of active nuclei; and (3) formation of larger nanoparticles via a growth process, which may be Ostwald ripening or aggregation. The nanoparticle growth is generally categorized by two processes: diffusion-controlled Ostwald-ripening and aggregation/coalescence. Nowadays, a molecule which can act both as a reducing and capping agent is preferred so that the reaction takes place in one step and there is no need for an external reducing agent. Multifunctional amines and nitrogen-containing polymers have also been tested for the synthesis of nanoparticles. Poly(ethylene oxide)-poly(propylene oxide)-based block copolymers are well known as dispersion stabilizers and templates for the synthesis of mesoporous materials and nanoparticles. Coordination chemistry offers simplicity, stable bonding, and ligand-metal specificity, enabling ligand-bearing components to be assembled into supramolecular structures using appropriate metal ions. This approach is particularly compatible with surface chemistry, as binding of metal ions activates the surface toward ligand binding, and vice versa. Some stabilizing agents can also be used as a reducing agent. Ionic liquids (ILs) are a viable option as stabilizing agents because of their ionic character and can be easily made task-specific as phase-transfer catalysts due to their tunable nature. Ligand exchange reactions have proven a particularly powerful approach to incorporate functionality in the ligand shell of thiol-stabilized nanoparticles and are widely used to produce organic- and water-soluble nanoparticles with various core sizes and functional groups. NMNPs can be intercalated into the gallery regions of montmorillonite and formed hybrid framework. Models of particle (crystal) development consider two basic steps: nucleation and growth. The creation of a new phase from a metastable state is nucleation. Seed-mediated growth method has been demonstrated to be a powerful synthetic route to generate a range of different types of metal nanoparticles. This method separates the nucleation and growth stage of nanoparticle syntheses by introducing presynthesized small seed particles into a growth solution typically containing a metal precursor, reducing agent, surfactants, and some additives. Dissolution of silver nanoparticles, for example, occurs through oxidation of metallic Ag and release of Ag+ into solution (or dissolution rate is accelerated). Release of Ag+ is determined by intrinsic physicochemical properties of silver nanoparticles and by those of the solution. Parameters that either enhance or suppress silver nanoparticle dissolution are ionic strength, pH, dissolved oxygen concentration, temperature, dissolved complexing ligands (organic matter, sulfur, chlorine), silver surface coating, shape, and size. The surfactants find their way to various environmental segments and thus pose serious health hazards. Several different polymer-based anticancer agents have been approved for clinical use, for passive tumor targeting. Prominent examples of macromolecular drug carrier systems evaluated in patients are poly(ethylene glycol), poly(l-glutamic acid), poly[N-(2-hydroxypropyl)methacrylamide], and their copolymers. Copolymers based on N-(2-hydroxypropyl)methacrylamide (i.e., HPMA) were used to improve the tumor-directed delivery of doxorubicin.
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as a treatment of cancer often relies on the ability of cytotoxic agents to kill or damage cells which are reproducing. This cancer treatment uses one or more anticancer drugs (chemotherapeutic agents) as part of a standardized chemotherapy regimen. Chemotherapy is one of the major categories of medical oncology (the medical discipline specifically devoted to pharmacotherapy for cancer).
Chemotherapeutic agents
are also known as cytotoxic agents. These are generally used to treat cancer. It includes alkylating agents, antimetabolites, antitumor antibiotics, anthracyclines, and topoisomerase inhibitors.
Chemotherapeutics
such as doxorubicin, cisplatin, and paclitaxel are selectively destructive to malignant cells and tissues.
Cross-link
is a bond that links one polymer chain to another. They can be covalent bonds or ionic bonds. When the term “cross-linking” is used in the synthetic polymer science field, it usually refers to the use of cross-links to promote a difference in the polymers’ physical properties. When “cross-linking” is used in the biological field, it refers to the use of a probe to link proteins together to check for protein–protein interactions, as well as other creative cross-linking methodologies.
DNA replication
is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance. DNA is made up of a double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication.
Hemolysis
or haemolysis, also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g., blood plasma). Hemolysis may occur in vivo or in vitro (inside or outside the body).
Metastatic cancer, or metastatic tumor,
is one which has spread from the primary site of origin (where it started) into different area(s) of the body. Metastasis is the spread of cancer cells to new areas of the body (often by way of the lymph system or bloodstream).
Photodynamic therapy (PDT)
is a clinically approved and minimally invasive therapy that uses a nontoxic light-sensitive compound (photosynthesizer) that is readily absorbed by abnormal cells. When exposed to a specific wavelength of light, the photosynthesizer is activated to produce changes in endothelial cell integrity that ultimately produces vascular disruption.
Rheumatoid arthritis (RA)
is a long-lasting autoimmune disorder that primarily affects joints. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body. The disease may also affect other parts of the body. This may result in a low red blood cell count, inflammation around the lungs, and inflammation around the heart slimicide is a chemical that prevents the growth of slime in paper stock.
Spacer
the most developed peptide linker for triggered release of covalently attached drug is the glycylphenylalanylleucylglycine (GFLG) tetra-peptide spacer. This spacer is often employed in published polymer anticancer conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA).
Therapeutic index (TI)
(also referred to as therapeutic ratio) is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxicity. The related terms therapeutic window and safety window refer to a range of doses which optimize between efficacy and toxicity, achieving the greatest therapeutic benefit without resulting in unacceptable side effects or toxicity.
Die im Laufe eines Jahres in der „adhäsion“ veröffentlichten Marktübersichten helfen Anwendern verschiedenster Branchen, sich einen gezielten Überblick über Lieferantenangebote zu verschaffen.