Development of Aptamer-Functionalized Gold Nanoparticles as Probes in Point-of-Care Diagnostic Device for Rapid Detection of Multidrug-Resistant Bacteria in <i>Bombyx mori</i> L.

The sericulture industry suffers severe crop losses due to various silkworm diseases, necessitating the development of further technologies for rapid pathogen detection. Here, we report an all-in-one portable biosensor that combines conjugated gold nanoparticles (Au NPs) with an aptamer-based lateral flow assay (LFA) platform for the real-time analysis of Mammaliicoccus sp. and Pseudomonas sp. Our platform enables sample-to-answer naked eye detection within 5 min without any cross-reactivity with other representatives of the silkworm pathogenic bacterial group. This assay was based on the sandwich-type format using a bacteria-specific primary aptamer (Apt1) conjugated with 23 nm +/- 1.27 nm Au NPs as a signal probe and another bacteria-specific secondary aptamer (Apt2)-coated nitrocellulose membrane as a capture probe. The hybridization between the signal probe and the capture probe in the presence of bacteria develops a red band in the test line, whose intensity is directly proportional to the bacterial concentration. Under the optimal experimental conditions, the visual limit of detection of the strip for Mammaliicoccus sp. and Pseudomonas sp. was 1.5 x 10(4) CFU/mL and 1.5 x 10(3) CFU/mL, respectively. Additionally, the performance of the LFA device was validated by using a colorimetric assay, and the results from the colorimetric assay are consistent with those obtained from the LFA. Our findings indicate that the developed point-of-care diagnostic device has significant potential for providing a cost-effective, scalable alternative for the rapid detection of silkworm pathogens

Multifunctional silver nanoparticle embedded eri silk cocoon scaffolds against burn wounds-associated infection

Antimicrobial wound dressings offer enhanced efficacy compared to conventional dressing platforms by limiting bacterial infections, expediting the healing process, and creating a barrier against additional wound contamination. The use of silk derived from silkworm cocoons in wound healing applications is attributed to its exceptional characteristics. Compared to mulberry silk, sericin from non-mulberry cocoons has higher water exchange mobility and moisture retention. Eri, a non-mulberry silkworm, is an unexplored source of silk with an eco-friendly nature of production where the natural life cycle of silkworms is not disrupted, and no moths are sacrificed. This work reports on an eri silk cocoon-based scaffold decorated with silver nanoparticles as a wound dressing material effective against burn-wound-associated multiple-drug-resistant bacteria. The UV-vis spectroscopy showed maximum absorbance at 448 nm due to the surface plasmon resonance of silver nanoparticles. FT-IR spectra exhibited the functional groups in the eri silk proteins accountable for the reduction of Ag+ to Ag0 in the scaffold. SEM-EDX analysis revealed the presence of elemental silver, and XRD analysis confirmed their particle size of 5.66-8.82 nm. The wound dressing platform showed excellent thermal stability and hydrophobicity, fulfilling the criteria of a standard waterproof dressing material, and anticipating the prevention of bacterial biofilm formation in chronic wounds. The scaffold was found to be effective against both Staphylococcus aureus (MTCC 87) and Pseudomonas aeruginosa (MTCC 1688) multiple-drug-resistant pathogens. Electron microscopy revealed the bacterial cell damage, suggesting its bactericidal property. The results further revealed that the scaffold was both hemocompatible and cytocompatible, suggesting its potential application in chronic wounds such as burns. As an outcome, this study presents a straightforward, cost-effective, and sustainable way of developing a multifunctional wound dressing platform, suggesting its significant therapeutic potential in clinical and biomedical sectors and facile commercialization. Antimicrobial wound dressings offer enhanced efficacy compared to conventional dressing platforms by limiting bacterial infections, expediting the healing process, and creating a barrier against additional wound contamination

Effect of Biogenic Gold Nanoparticles on Gut Microbiota Composition during Larval-to-Pupal Transition in Bombyx mori L.

This study investigates the effects of biogenic gold nanoparticles (Au NPs), synthesized using an aqueous leaf extract of Morus alba, as a feed supplement on the gut microbiota of Bombyx mori. The synthesized Au NPs displayed a characteristic peak absorbance at 545 nm in the UV-vis spectrum, indicative of surface plasmon resonance (SPR), a phenomenon typical of Au NPs. Fourier-transform infrared (FTIR) spectra revealed the functional groups responsible for the reduction of Au(III) to Au(0). The crystallinity of the synthesized Au NPs was checked using TEM and XRD analysis. TEM micrographs further exhibited the quasi-spherical, monodispersed, well-scattered nature of the Au NPs with an average particle size of 34.15 ± 9.45 nm. The presence of (111), (200), (220), and (311) planes in Bragg’s reflections confirmed the face-centered-cubic (fcc) crystalline nature of elemental gold. The LC-MS/MS study revealed that the presence of two zwitterionic species (mainly betaine) stabilizes the Au NPs by the formation of positive sol micelles. Biogenic Au NPs at 40-60 ppm concentrations significantly improved larval growth, effective rearing rate (ERR), filament length, and cocoon quality without affecting silk fineness. Doses below 40 ppm were biologically ineffective, while concentrations above 60 ppm triggered oxidative stress and cytotoxicity. Similarly, gut microbiota analysis revealed notable compositional shifts at the phylum, class, family, and genus levels. There was a decrease in the relative abundance of the phylum Cyanobacteria, concomitant with a significant enrichment of stress-resilient taxa, including Planctomycetes, Micrococcaceae, Parcubacteria, and Candidatus Adlerbacteria. Predictive functional profiling using PICRUSt indicated enhanced microbial pathways linked to metabolism, stress response, and detoxification. These results suggest that biogenic Au NPs influence host-microbiome interactions, facilitating improved nutrient assimilation and silk production. However, further research is required to evaluate the long-term safety and ecological impact before widespread use in sericulture

Silk-based nano-biocomposite scaffolds for skin organogenesis

Silk produced by silkworms or spiders offers biocompatibility, biodegradability, stability, and biomechanical strength, making it an excellent biomaterial for wound bandages/dressings and skin grafts. Silk scaffolds are also bioactive matrices necessary to restore the healing cascade and barrier properties that induce skin organogenesis in chronic wounds. Silk-based composites are being used to protect wounds from infections. Many studies were conducted via 2D cell culture and in vivo approaches to explain the interaction between skin tissue and silk. In addition to the difficulties that 2D cell culture techniques have in mimicking skin tissue, the physiological dif-ferences and immunological incompatibility between in vivo models and human skin tissue make it more complicated to understand the effectiveness of silk scaffolds. This leads to excessive experimental animal usage and false positive or negative results for the clinical stage. Alternatively, organ-like microtissues (organoids, spheroids, among others) produced using stem cells can be a real stakeholder in measuring the success of wound patches due to their 3D structure, cellular diversity, and high yield. However, the fabrication procedure of the microtissues is highly Matrigel-dependent, and it is not the best choice for the studies due to its indeterminate nature, protein concentration, and composition. Silk-based nano-biocomposites can be a good candidate owing to their features above for 3D skin cell culture studies. Here, we evaluated the current applications of silk-based materials in wound healing and their possible applications in 3D tissue engineering for microtissues