colloidal Au and Ag nanoparticles
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.