colloidal Au and Ag nanoparticles

Overview

Colloidal gold (Au) and silver (Ag) nanoparticles are nanoscale suspensions of metallic particles, typically ranging from 1 to 100 nanometers in diameter, dispersed in an aqueous or organic medium. Their defining physicochemical property is localized surface plasmon resonance (LSPR), an optical phenomenon arising when incident light drives collective oscillations of conduction-band electrons at the particle surface. This resonance produces extraordinarily intense electromagnetic near-fields that underpin the technique known as surface-enhanced Raman scattering (SERS), in which analyte molecules adsorbed on or near the nanoparticle surface exhibit Raman signal enhancements of several orders of magnitude. Gold nanoparticles are prized for their chemical inertness, tunable optical properties, and straightforward surface functionalization, while silver nanoparticles offer even larger SERS enhancement factors and well-documented intrinsic antimicrobial activity attributable to the release of Ag⁺ ions and generation of reactive oxygen species that disrupt bacterial membranes and metabolic pathways.

Beyond their spectroscopic utility, Ag nanoparticles interact directly with biological systems: they impair cell-wall integrity in gram-positive and gram-negative bacteria, sensitize tumor cells to ionizing radiation, and can be incorporated into biomaterial scaffolds to confer sustained antibacterial protection. The dual functionality of colloidal Au and Ag nanoparticles—simultaneously serving as ultrasensitive analytical substrates and as bioactive agents—has made them central to a wide and rapidly expanding body of biomedical research spanning diagnostics, wound care, oncology, and bone regeneration.

Focus of Latest Publications

Spectroscopic Diagnostics and Bacterial Identification

A 2026 study published in ACS Nano (PMID 41985172) explicitly employed colloidal Au and Ag nanoparticles as SERS substrates to obtain reproducible Raman spectra from intact bacterial cells. By coupling these nanoparticle substrates with explainable artificial intelligence—specifically SHapley Additive exPlanations (SHAP) to decode model decisions—and a deep neural network classifier, the investigators achieved highly accurate species-level discrimination of bacteria and identified spectral signatures characteristic of each organism. This work illustrates how colloidal metallic nanoparticles can bridge nanophotonics and machine learning for rapid, culture-free microbial diagnostics.

A complementary study in Spectrochimica Acta Part A (PMID 41740396) applied silver nanoparticles as SERS substrates for simultaneous quantification of HDL and LDL cholesterol in clinical blood serum, a measurement directly relevant to assessing cardiovascular disease risk. Chemometric processing of the SERS spectra enabled multianalyte discrimination from complex biological matrices, demonstrating the translational potential of Ag-NP-based sensing for routine clinical chemistry.

A third spectroscopic study in Mikrochimica Acta (PMID 42120743) extended the SERS platform to gold nanoparticles deposited on the metal-organic framework ZIF-8, forming a ZIF-8@AuNPs nanocomposite for ultra-sensitive detection of urinary Metabolites including adenosine triphosphate, uric acid, adenine, and creatinine—compounds whose dysregulation is linked to metabolic and renal disease.

Green Biosynthesis and Antimicrobial Applications

Several recent studies have investigated phytofabrication routes—using plant extracts to reduce metal salts into nanoparticles without hazardous chemical reductants. Research published in Microbial Pathogenesis (PMID 41936968) synthesized silver nanoparticles from Origanum majorana (marjoram) leaf extract and evaluated their antibacterial efficacy, dye degradation capacity, and hemolytic safety profile. Separately, a study in Biochemical and Biophysical Research Communications (PMID 41904914) used Mikania micrantha extract to biosynthesize AgNPs, assessing their catalytic and antimicrobial properties alongside cytotoxicity against Caco-2 intestinal cancer cells to gauge safety at the intestinal epithelial boundary.

Wound Healing Biomaterials

Multiple groups have embedded silver nanoparticles into advanced wound-care scaffolds to couple structural support with sustained antimicrobial action. A study in ACS Applied Materials & Interfaces (PMID 42100849) incorporated tea polyphenol (TP)-capped AgNPs (TP-AgNPs) into a BDDE-crosslinked deacetylated sphingan WL gum (DWL) matrix, yielding a green multifunctional hydrogel (TP-Ag@BDH) with combined antibacterial and antioxidant activity tested in infected wound models. A complementary approach described in Journal of Materials Chemistry B (PMID 42023956) constructed a functionally graded bilayer polyurethane sponge in which a hydrophobic macroporous layer bearing a polydopamine coating was loaded with silver nanoparticles (PUF@P-Ag) to achieve stage-adaptive repair of infected full-thickness skin defects across the full wound-healing cycle.

Oncology and Radiosensitization

Research published in Pflügers Archiv (PMID 42156577) positioned silver nanoparticles as a promising therapeutic modality for glioblastoma, demonstrating that AgNPs can radiosensitize human glioblastoma cells and that this effect is mediated in part through the KCa3.1 potassium channel. This finding adds a mechanistic dimension to the growing interest in AgNPs as adjuvants to radiotherapy for aggressive brain tumors.

Bone Regeneration Scaffolds

A study in ChemBioChem (PMID 42107094) fabricated AgNP-doped polycaprolactone–silk fibroin (PCL-SF) electrospun nanofibrous scaffolds, drawing on the structural protein from Bombyx mori silk, to achieve simultaneous osteogenic stimulation and antimicrobial protection—properties targeting the dual challenge of infection and bone regeneration in orthopedic applications.

Key Publications

• NEWJun Ameliorating effects of Stevia extract combined with green-synthesized silver nanoparticles coated with soy soluble polysaccharides on diabetic wounds in a rat model. (Nanoscale, 2026, PMID 42148914): "The use of silver nanoparticles (AgNPs) as a new treatment for diabetic wound (DW) healing is limited due to cytotoxicity."
• Jun Toward Precision Electrochemical Sensing of CFTR Function in Cystic Fibrosis Models. (Analytical chemistry, 2026, PMID 42240701): "In this study, a flexible electrochemical sensor modified with silver nanoparticles was developed and applied for the electrochemical quantification of chloride ions in CF epithelial cell models."
• Jun Biosynthesis of ecofriendly antibacterial nanoparticles with healing effects in a murine diabetic skin infection model. (Scientific reports, 2026, PMID 42297939): "Therefore, this study reports the eco-friendly synthesis of silver (AgNPs), zinc oxide (ZnONPs), and chitosan-tripolyphosphate nanoparticles (Cs-TPP-NPs) using green tea extract (GTE) and gamma irradiation."
• Jun Controllable synthesis of uniform chitosan hydrogel-based SERS substrates for rapid detection of thiram on various fruit surfaces. (Food chemistry, 2026, PMID 41935476): "Herein, we developed a series of flexible silver nanoparticles@chitosan hydrogel (AgNPs@CSHG) SERS substrates by a controllable in-situ growth strategy, creating uniformly distributed SERS hot spots through electrostatic interactions between silver ions and the hydroxyl/amino groups in chitosan molecules."
• Jun Eco-superior phyto-derived fluorescent silver nanoparticles: A novel, rapid and ultra-sensitive nano sensor with exceptional greenness, whiteness, and blueness for etoricoxib quantification in pharmaceuticals and biological matrices. (Analytica chimica acta, 2026, PMID 41965306): "This study establishes the first direct spectrofluorimetric determination of Etoricoxib via silver nanoparticles, successfully eliminating the need for both tedious derivatization and aggressive chemical conditions."
• Jun Development of a chemometric-assisted SERS method for simultaneous analysis of HDL and LDL cholesterol in blood serum with silver nanoparticles as substrate. (Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2026, PMID 41740396): "using clinical blood serum samples along with silver nanoparticles (Ag-NPs) as the SERS substrate."
• Jun Phytofabricated Silver Nanoparticles from Origanum majorana: Anti-Pathogenic Activity and Biocompatibility Evaluation. (Microbial pathogenesis, 2026, PMID 41936968): "Phytofabrication of silver nanoparticles from Origanum majorana leaf extract and its efficacy were tested through dye degradation, antibacterial activity, and hemolytic assay."
• May Evaluating the catalytic and antimicrobial activities of biosynthesized silver nanoparticles using Mikania micrantha and their toxicity on Caco-2 human cancer cells. (Biochemical and biophysical research communications, 2026, PMID 41904914): "This investigation explores the thermal resistance and degradation behaviour of silver nanoparticles (AgNPs)."
• May KCa3.1 mediates radioresistance of silver nanoparticles in human glioblastoma cells. (Pflugers Archiv : European journal of physiology, 2026, PMID 42156577): "Silver nanoparticles (AgNPs) have emerged as a promising therapeutic tool for managing glioblastoma (GB), particularly in radiosensitisation."
• May Green Antibacterial-Antioxidant Hydrogel for Infected Wound Healing: Tea Polyphenol and Biosynthesized Silver Nanoparticles in a Deacetylated Sphingan WL Matrix. (ACS applied materials & interfaces, 2026, PMID 42100849): "This study developed a green-synthesized multifunctional hydrogel (TP-Ag@BDH) by incorporating tea polyphenol (TP) and TP-capped silver nanoparticles (TP-AgNPs) into a BDDE-cross-linked matrix of deacetylated sphingan WL gum (DWL)."