Silver Nanoparticle-Decorated Silica Nanospheres and Arrays as Potential Substrates for Surface-Enhanced Raman Scattering

A novel SERS-lateral flow assay (LFA) tray for monitoring of miR-155-5p during pyroptosis in breast cancer cells

In the study, a novel surface-enhanced Raman scattering (SERS)-lateral flow assay (LFA) tray for the real-time detection of pyroptosis-associated miR-155-5p in breast cancer cells was established and validated. The SERS probe modified with monoclonal antibodies and functionalized HP1@5-FAM was first synthesized. When miR-155-5p was present, HP1@5-FAM on the SERS probe specifically recognized target miRNAs and hybridized with them, resulting in HP2 on the T line only capturing some SERS probes that were not bound to miR-155-5p. The T line appeared as a light orange band or there was no color change, and the corresponding Raman detection result showed a weak or insignificant Raman signal. The SERS probe showed high selectivity, satisfactory stability, and excellent reproducibility, and the limit of detection (LOD) for miR-155-5p was 7.26 aM. Finally, the proposed SERS-LFA tray was applied to detect miR-155-5p in MBA-MD-468 cells that underwent varying degrees of pyroptosis, and the detection results of SERS were consistent with those of the conventional real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. The study demonstrated that the SERS-LFA tray was a convenient and ultrasensitive method for miR-155-5p real-time detection, which could provide more detailed information for pyroptosis and be of potential value in guiding the treatment of breast cancer.

PCL/gelatin nanofibers embedded with doxorubicin-loaded mesoporous silica nanoparticles/silver nanoparticles as an antibacterial and anti-melanoma cancer

Melanoma cancer wound healing is critical and complex and poses a significant challenge to researchers. Drug resistance, adverse side effects, and inefficient localization of chemotherapeutic drugs limit common treatment strategies in melanoma cancer. Using drug delivery nanostructures with low side effects and high efficiency, besides having antibacterial and antiseptic properties, can effectively repair the damage caused by the disease. To this end, this study aimed to develop a drug delivery nanosystem based on doxorubicin (DOX)-loaded amine-functionalized mesoporous silica nanoparticles (MSNs), linked with green synthesized silver nanoparticles (AgNPs). Characterization methods including microscopic methods and X-ray diffraction (XRD) confirmed the synthesis and functionalization of the well-dispersed nanoparticles with nanosized and uniform structures. The poly(ε-caprolactone) (PCL) nanofibers as a strong scaffold were produced by the blow spinning method and DOX-loaded nanoparticles were blow spun on PCL nanofibers along with gelatin solution. The resulting nanosystem including nanofibers and nanoparticles (NFs/NPS) showed a fine loading percent with a proper release profile of DOX and AgNPs and low hemolysis activity. Moreover, besides preventing infection by AgNPs, the DOX-loaded NFs/NPs could effectively destroy melanoma cancer cells. The attachment of normal cells to the nanoparticles-loaded nanofibers scaffold revealed the possibility of healing wounds caused by melanoma cancer.

Detection of glutathione in dairy products based on surface-enhanced infrared absorption spectroscopy of silver nanoparticles

In this paper, silver nanoparticles (AgNPs) were prepared as enhanced substrates for the detection of glutathione in dairy products by polyol reduction of silver nitrate. The infrared spectra were collected and analyzed by surface-enhanced infrared absorption spectroscopy (SEIRA) method of transmission mode using a cell of calcium fluoride window sheet immobilization solution for the study. The disappearance of the thiol (-SH) absorption peak in the infrared spectrum, and the shift of its characteristic absorption peak when glutathione was bound to AgNPs solvate indicated the Ag-S bond interaction and the aggregation of AgNPS. AgNPs accumulate to form "hot spots", resulting in enhanced electromagnetic fields and thus enhanced infrared signals of glutathione. The intensity of the characteristic absorption peak at 1,654 cm^-1 (carbonyl C=O bond stretching) was used for the quantitative analysis of glutathione. After optimizing the conditions, glutathione content in pretreated pure milk and pure ewe's milk was determined using AgNPs in combination with SEIRA. Good linearity was obtained in the range of 0.02-0.12 mg/mL with correlation coefficients (R ²) of 0.9879 and 0.9833, respectively, and LOD of 0.02 mg/mL with average spiked recoveries of 101.3 and 92.5%, respectively. The results show that the method can be used for accurate determination of glutathione content in common dairy products.

Roll to roll in situ preparation of recyclable, washable, antibacterial Ag loaded nonwoven fabric

Functional fabrics with antibacterial performance are more welcome nowadays. However, the fabrication of functional fabrics with durable, steady performance via a cost-effective way remains a challenge. Polypropylene (denoted as PP) nonwoven fabric was modified by polyvinyl alcohol (denoted as PVA), followed by the in-situ deposition of silver nanoparticles (denoted as Ag NPs) to afford PVA-modified and Ag NPs-loaded PP (denoted as Ag/PVA/PP) fabric. The encapsulation of PP fiber by PVA coating contributes to greatly enhancing the adhesion of the loaded Ag NPs to the PP fiber, and the Ag/PVA/PP nonwoven fabrics exhibit significantly improved mechanical properties as well as excellent antibacterial activity against Escherichia coli (coded as E. coli). Typically, the Ag/PVA/PP nonwoven fabric obtained at a silver ammonia concentration of 30 mM has the best mechanical properties and the antibacterial rate reaches 99.99% against E. coli. The fabric retains excellent antibacterial activity even after washing for 40 cycles, showing prospects in reuse. Moreover, the Ag/PVA/PP nonwoven fabric could find promising application in industry, thanks to its desired air-permeability and moisture-permeability. In addition, we developed a roll-to-roll production process and conducted preliminary exploration to verify the feasibility of this method.

SiO2 Microsphere Array Coated by Ag Nanoparticles as Raman Enhancement Sensor with High Sensitivity and High Stability

In this paper, a monolayer SiO₂ microsphere (MS) array was self-assembled on a silicon substrate, and monolayer dense silver nanoparticles (AgNPs) with different particle sizes were transferred onto the single-layer SiO₂ MS array using a liquid–liquid interface method. A double monolayer “Ag@SiO₂” with high sensitivity and high uniformity was prepared as a surface-enhanced Raman scattering (SERS) substrate. The electromagnetic distribution on the Ag@SiO₂ substrate was analyzed using the Lumerical FDTD (finite difference time domain) Solutions software and the corresponding theoretical enhancement factors were calculated. The experimental results show that a Ag@SiO₂ sample with a AgNPs diameter of 30 nm has the maximal electric field value at the AgNPs gap. The limit of detection (LOD) is 10⁻¹⁶ mol/L for Rhodamine 6G (R6G) analytes and the analytical enhancement factor (AEF) can reach ~2.3 × 10¹³. Our sample also shows high uniformity, with the calculated relative standard deviation (RSD) of ~5.78%.