Metal Nanoparticles

Ferric oxide (Fe₃O₄) is widely used in magnetic resonance imaging (MRI), magnetic separation, targeted drug delivery, tumor hyperthermia, cell labeling and separation, and as a contrast agent and enhancement agent in retinal detachment repair surgery due to its stable material properties, good biocompatibility, high strength, and lack of toxic side effects. It is also used as a catalyst carrier, microwave absorbing material, and magnetic recording material. Xianfeng has developed numerous derivatives of ferric oxide, including oleic acid-modified ferric oxide, PEG-terminated ferric oxide, DMSA-modified ferric oxide, polylysine-modified ferric oxide, carboxylated dextran-modified ferric oxide nanoparticles, streptavidin-modified ferric oxide particles, thiol-modified ferric oxide magnetic nanoparticles, and polyethyleneimine (PEI)-modified magnetic ferric oxide nanoparticles, among others. This wide range of modifications provides numerous options for subsequent experiments.

Hollow mesoporous copper sulfide nanoparticles are nanomaterials with unique structures and properties. Their hollow mesoporous structure enables the encapsulation of small molecules, facilitating in vivo delivery, while their surface can be functionalized for further modification. Due to their excellent properties, hollow mesoporous copper sulfide nanoparticles are widely used in fields such as magnetic resonance imaging, biosensoring, and nanoprobe construction.

Glycyrrhizic acid (GA) is a saponin derived from the root of the traditional Chinese medicine licorice. It possesses various pharmacological effects, such as anti-inflammatory, antioxidant, immunomodulatory, and antiviral activity. In addition to its own pharmacological activity, GA can form complexes with many drugs and other natural products. Structurally, glycyrrhizic acid is an amphiphilic molecule; its hydrophilic portion consists of glucuronic acid residues, while its hydrophobic portion is composed of glycyrrhizic acid residues. It can aggregate in water to form self-assembled micelles. Glycyrrhizic acid encapsulates hydrophobic drugs through self-assembly into host-guest complexes, thereby increasing drug solubility and inhibiting precipitation. These complexes can also achieve sustained and controlled release of encapsulated drugs. Therefore, glycyrrhizic acid micelles can serve as drug carriers to improve the absorption of hydrophobic drugs.

Titanium dioxide magnetic beads are magnetic microparticle carriers whose surface is coated with titanium dioxide nanoparticles. This material is commonly used in protein digests of biological samples for the simple, convenient, efficient, highly specific, and reproducible enrichment of phosphorylated peptides. The surface properties of titanium dioxide magnetic beads make them show no significant preference for monophosphorylated or polyphosphorylated peptides, making them ideal for single-step enrichment of phosphorylated peptides in mass spectrometry-based proteomics analysis.

Carboxylated magnetic microspheres are magnetic microspheres with abundant carboxyl functional groups on their surface. They are usually composed of superparamagnetic materials (such as Fe₃O₄) and polymer materials, with polystyrene microspheres as the core.

APTS Fe₂O₃ Nanoparticles (Aminated ferric oxide magnetic nanoparticles) are magnetic nanomaterials modified with amino functional groups using APTS. This material consists of a ferric oxide (Fe₃O₄) nanoparticle core and an amino (-NH2) surface modification layer. The aminated surface helps improve the biocompatibility of the nanoparticles and reduce cytotoxicity. The amino functional groups can be further chemically modified for coupling with biomolecules such as drugs, proteins, and nucleic acids. The amino functional groups undergo protonation at different pH values, resulting in different surface charges on the nanoparticles in different pH environments.

Carboxymethyl dextran-modified iron(III) oxide nanoparticles are composite materials in which carboxymethyl dextran (CMD) is introduced onto the surface of iron(III) oxide (Fe₃O₄) nanoparticles through chemical modification. Carboxymethyl dextran is a water-soluble polysaccharide; its hydrophilicity and biocompatibility are enhanced by converting the hydroxyl groups of the dextran into carboxymethyl groups (-COOH).

Thiol-modified magnetite nanoparticles are prepared via high-temperature pyrolysis and surface-modified with thiol functional groups. Magnetite is widely used in magnetic resonance imaging, magnetic separation, targeted drug delivery, tumor hyperthermia, cell labeling and separation, as a contrast agent, and in retinal detachment repair surgery due to its stable properties, good biocompatibility, high strength, and lack of toxicity. It is also used as a catalyst carrier, microwave absorbing material, and magnetic recording material. Xianfeng has developed numerous derivatives of magnetite, including oleic acid-modified magnetite, magnetite with different PEG ends, DMSA-modified magnetite, polylysine-modified magnetite, carboxylated dextran-modified magnetite nanoparticles, streptavidin-modified magnetite particles, thiol-modified magnetite magnetic nanoparticles, and polyethyleneimine (PEI)-modified magnetic magnetite nanoparticles, among others.

Polyethyleneimine (PEI)-modified magnetic iron(III) oxide (Fe₃O₄) nanoparticles are a composite nanomaterial that combines the properties of magnetic nanoparticles and polyethyleneimine. Polyethyleneimine is a highly branched polymer with a high density of amino groups. These amino groups stabilize the Fe₃O₄ nanoparticles and provide sites for further functionalization. The amino groups of PEI impart a high surface positive charge to the Fe₃O₄ nanoparticles, which helps enhance their interaction with negatively charged cell membranes.

Bovine serum albumin-modified gold nanoclusters (BSA-Au NCs) are nanomaterials combining gold nanoclusters and bovine serum albumin (BSA). Composed of several to dozens of gold atoms forming the core of the gold nanoclusters, BSA acts as a protective ligand, coating the surface of the gold nanoclusters. BSA-Au NCs are widely used due to their high luminescence properties and stability over a wide pH range. When Au(III) ions are introduced into a BSA solution, BSA acts as a scaffold protein, isolating and capturing Au ions, similar to the biomineralization behavior of inorganic ions in organisms in nature. The captured Au ions are then reduced in situ by BSA to form Au NCs. The synthesized Au NCs consist of 25-Au atoms and are stable in BSA as BSA-Au NCs, exhibiting strong red fluorescence. BSA-Au NCs possess good biocompatibility and their surface is easily modified or functionalized, making them attractive for many biomedical applications.

Gold nanoparticles, also known as gold nanoparticle colloids, are colloidal systems formed by dispersing gold nanoparticles in a solution. Common methods for preparing gold nanoparticle colloids include the sodium citrate reduction of chloroauric acid method, also called the seed growth method or electrochemical synthesis method. The color of gold nanoparticle colloids changes with the size of the gold nanoparticles. Generally, the larger the diameter of the gold nanoparticles, the more the wavelength of light absorbed by the solution shifts towards longer wavelengths, and the particles will exhibit the complementary color of the absorbed light.

PLL coated Fe₂O₃ nanoparticles (Polylysine-modified ferric oxide magnetic nanoparticles) consist of a polylysine (PLL)-modified ferric oxide (Fe₂O₃) core and pure water.

Carboxylated iron oxide nanoparticles (high-temperature pyrolysis method) are obtained by modifying DMSA on the basis of XFJ67 to obtain carboxyl groups, which converts oil-soluble nanoparticles into water-soluble nanoparticles, making them more suitable for applications in the biological field.

Nanoclusters are essentially ultrasmall nanomaterials, typically with diameters between 1 and 10 nm, composed of a specific number of metal atoms (approximately 10 to several hundred) and ligands. This structure places their size between that of small molecules and traditional nanoparticles, exhibiting quantum effects. When the size of the metal core approaches the Fermi wavelength of electrons, its band structure transitions from a continuous state to discrete energy levels, thus exhibiting molecular-like properties such as single-electron transitions, multiple absorption bands, and strong photoluminescence. Iron nanoclusters (FeNCs) are a class of ultrasmall fluorescent nanomaterials composed of several to tens of iron atoms. Synthesized using bovine serum albumin (BSA) as a template and protectant via a chemical reduction method, these materials possess excellent optical properties and biocompatibility. Furthermore, they can be functionalized through surface modification, leading to their wide application in fields such as bioanalysis, environmental monitoring, and disease diagnosis.

Citrate-modified ferric oxide nanoparticles are functionalized nanoparticles formed by attaching citric acid to the surface of Fe₃O₄ nanoparticles. Due to their excellent biocompatibility and stability, Citrate-modified ferric oxide nanoparticles can be used as drug carriers for drug delivery and contrast enhancement in magnetic resonance imaging (MRI).

Carboxylated magnetic microspheres (low nonspecificity) are functionalized nano- or micron-sized magnetic particles with abundant carboxyl functional groups on their surface. Special chemical treatments reduce the likelihood of nonspecific adsorption. This 1μm carboxylated magnetic microsphere features a core-shell structure: a PS core, an outer layer of iron oxide (Fe₃O₄), and an outermost encapsulation layer. The carboxyl groups are obtained through polymer modification. Exhibiting low nonspecific adsorption, these microspheres can covalently couple with bioligands such as peptides, proteins, antibodies, and oligonucleotides using specific chemical reagents (e.g., EDC), making them particularly suitable for cell sorting, affinity chromatography, and immunoassay.

Monodisperse Fe₃O₄ microspheres (Monodisperse iron oxide microspheres) are microspheres composed of magnetic materials, with iron oxide as the main component. These microspheres are very uniform in size and exhibit monodispersity, meaning that the sizes of the microspheres are very similar with minimal differences.

Nanomaterials with sizes ranging from 1 to 100 nm are generally referred to as nanocrystals. The preparation of platinum nanocrystals with controllable morphology was first reported in 1996. Pt, Ag, Au, Rh, and other nanocrystals have been synthesized using various methods. Platinum has a face-centered cubic (fcc) structure, but unlike Ag, Au, and Pd, it rarely forms twins; most platinum nanocrystals are single-crystal structures. XFJ116 platinum nanoparticles were prepared via a chemical reduction method, exhibiting uniform size and good dispersibility, and can also provide platinum nanoparticles with amino and carboxyl terminator modifications.

Gold nanoclusters (AuNCs) are molecular-level aggregates consisting of a core of several to dozens of gold atoms, protected by organic monomers such as thiol compounds or proteins. GSH-AuNCs utilize glutathione (a thiol-containing tripeptide) as both a reducing agent and a protecting group, reacting chemically with gold atoms to form nanoclusters, representing a transitional state between metal atoms and metal nanoparticles. Due to size effects and the emergence of quantized energy levels, GSH-AuNCs possess unique optical properties, such as tunable fluorescence emission spectra. Their fluorescence emission wavelength can be tuned with variations in particle size and composition.

Reactive oxygen species responsive hydrogels are a novel class of smart hydrogels, formed by the cross-linking of ROS-responsive modules through covalent, coordination, or supramolecular interactions. Due to the introduction of these ROS-responsive modules, these hydrogels exhibit a sensitive response to the oxidative stress microenvironment present in organisms. PVA-TSPBA hydrogel is a hydrogel formed by the cross-linking polymerization of polyvinyl alcohol (PVA) and the reactive oxygen species-sensitive cross-linking agent N1-(4-benzyl borate)-N3-(4-phenyl borate)N1,N1,N3,N3-tetramethyl-1,3-propanediamine (TSPBA). This hydrogel consists of two parts: a boric acid precursor (TSPBA) and an aqueous solution of PVA. The boric acid bonds on TSPBA and the hydroxyl groups on PVA rapidly cross-link to form borate ester bonds, thus forming the hydrogel.