Au@bovine serum albumin nanoparticle-based acid-resistant nanozyme quartz crystal microbalance sensing of urine glucose

A robust, efficient and sensitive quartz crystal microbalance (QCM) for glucose detection has been constructed using Au@bovine serum albumin (Au@BSA) nanoparticles as an active layer. The nanoparticles serve as tandem nanozymes and their stability over natural enzymes enable the sensor to show a wider linear dynamic range between 0.05 and 15 mM, a higher acid-resistance (pH 2.0-8.0) and heat-resistance (35-60 °C) than conventional glucose oxidase (GOx)-based sensors. The sensor has been further applied to measure glucose content in artificial urine directly without dilution, where the recovery of 99.6-105.2% and the relative standard deviations (RSDs) below 0.88% confirm a good reproducibility for the measurement results. In addition, the developed Au@BSA QCM sensor can retain 95% of its initial activity after 40 days of storage. Overall, the Au@BSA sensor shows better comprehensive performance than the commercial sensor strips for urine glucose analysis and provides a promising approach in a more precise and robust manner.

Recent advances in carbon nanotubes-based biocatalysts and their applications

Enzymes have been incorporated into a wide variety of fields and industries as they catalyze many biochemical and chemical reactions. The immobilization of enzymes on carbon nanotubes (CNTs) for generating nano biocatalysts with high stability and reusability is gaining great attention among researchers. Functionalized CNTs act as excellent support for effective enzyme immobilization. Depending on the application, the enzymes can be tailored using the various surface functionalization techniques on the CNTs to extricate the desirable characteristics. Aiming at the preparation of efficient, stable, and recyclable nanobiocatalysts, this review provides an overview of the methods developed to immobilize the various enzymes. Various applications of carbon nanotube-based biocatalysts in water purification, bioremediation, biosensors, and biofuel cells have been comprehensively reviewed.

A novel and high performance enzyme-less sensing layer for electrochemical detection of methyl parathion based on BSA templated Au–Ag bimetallic nanoclusters

In the present manuscript, a modified glassy carbon electrode with BSA templated Au–Ag bimetallic nanoclusters (Au–Ag@BSA/GCE) was employed for the rapid, selective and sensitive determination of methyl parathion (MP) as an enzyme-less electrochemical biosensor.

Not all protein-mediated single-wall carbon nanotube dispersions are equally bioactive

Single-wall carbon nanotubes (SWCNTs) have been dispersed with proteins to increase biocompatibility and specificity, but examinations of dispersion parameters on functional cellular uptake are required for utilization of SWCNTs in biological applications. Here we correlate conditions of SWCNT dispersion with various proteins to uptake these SWCNTs in NIH-3T3 fibroblasts and J774A.1 macrophage-like cells. We varied protein types (bovine serum albumin - BSA, lysozyme - LSZ, and γ-globulins - γG), protein : SWCNT ratio and sonication time. Each protein created stable, high yield (~25%) dispersions in water while preserving intrinsic SWCNT fluorescence, but SWCNT-LSZ flocculated in media and SWCNT-γG formed clusters in both water and media, drastically altering cellular internalization. Dispersion quality and yield improved with increased protein : SWCNT - without substantial effects from depletion attraction, even at 100 : 1 protein : SWCNT - and slightly increased internalized SWCNTs for both NIH-3T3 and J774A.1 cells. Longer sonication time (12 versus 2 h) improved the dispersion yield and quality but caused minor damage to SWCNTs and altered protein structure. Cell association of SWCNT-BSA was homogenous and unaltered by sonication time. Bulk assay showed that cell association of SWCNT-LSZ and SWCNT-γG was altered with 12 versus 2 h sonication, but imaging of individual cells showed that these differences are likely from precipitation of clusters of SWCNT-LSZ and SWCNT-γG in media onto cells. Hence, the quality of SWCNT-protein dispersions in water does not necessarily correlate with bulk cellular uptake, and quantification at the level of individual cells is required to determine delivery efficacy.