ABSTRACT
Point-of-care (POC) diagnostic platforms are globally employed in modern smart technologies to detect events or changes in the analyte concentration and provide qualitative and quantitative information in biosensing. Surface plasmon-coupled emission (SPCE) technology has emerged as an effective POC diagnostic tool for developing robust biosensing frameworks. The simplicity, robustness and relevance of the technology has attracted researchers in physical, chemical and biological milieu on account of its unique attributes such as high specificity, sensitivity, low background noise, highly polarized, sharply directional, excellent spectral resolution capabilities. In the past decade, numerous nano-fabrication methods have been developed for augmenting the performance of the conventional SPCE technology. Among them the utility of plasmonic gold nanoparticles (AuNPs) has enabled the demonstration of plethora of reliable biosensing platforms. Here, we review the nano-engineering and biosensing applications of AuNPs based on the shape, hollow morphology, metal-dielectric, nano-assembly and heterometallic nanohybrids under optical as well as biosensing competencies. The current review emphasizes the recent past and evaluates the latest advancements in the field to comprehend the futuristic scope and perspectives of exploiting Au nano-antennas for plasmonic hotspot generation in SPCE technology.
ABSTRACT
Chitin and chitosan from silkworm pupae and egg shells show distinct properties with excellent antimicrobial properties and cytocompatiblity. Spent silkworm pupae and hatched egg shells are discarded as waste but contain valuable carbohydrates, proteins and lipids. Chitosan has excellent antimicrobial properties and is widely used for food, medical and biotechnological applications. In this paper, we report the properties of chitin and chitosan from silkworm pupae and egg shells in comparison to commercially available chitosan. Defatted and deproteinated pupae and shells were demineralized and later deacetylated to form chitosan. Thermal behavior, physical structure, antimicrobial activity and ability to support the attachment and growth of NIH3T3 cells were studied. Chitin and chitosan from both pupae and shells had similar structure and composition. Crystallinity of the pupae chitosan was 48% compared to 38% for egg shell chitosan. Silkworm chitosan showed considerably higher antibacterial and antifungal activity compared to standard. Cells were viable in the presence of pupae and egg shell chitosan in all the concentrations tested. Based on these observations, it can be inferred that silkworm pupae and shells provide a renewable and sustainable source for chitosan with properties suitable for food and medical applications.
