Lectin-Functionalized Chitosan Nanoparticle-Based Biosensor for Point-of-Care Detection of Bacterial Infections.

The WHO estimates an average of 10 million deaths per year due to the increasing number of infections and the predominance of drug resistance. To improve clinical outcomes and contain the spread of infections, the development of newer diagnostic tools is imperative to reduce the time and cost involved to reach the farthest population. The current study focuses on the development of a point-of-care technology that uses crystal violet entrapped, lectin functionalized chitosan nanoparticles to detect the presence of clinically relevant bacterial infections. Spherical nanoparticles of <200 nm in diameter make up the biosensing nanomaterial, showed specific clumping in the presence of bacteria to form visible aggregates as compared to a nonbacterial sample. Visible agglutination confirmed the presence of bacteria in the samples. The devices require just 100 µL of sample and were tested with various bacteria-spiked saline, simulated urine, artificial sputum, and simulated respiratory and wound swabs. The developed device did not require any sample preparation or sophisticated instruments while enabling rapid differentiation between bacterial and nonbacterial infections within 10 min. The in vitro results with bacteria-spiked simulated samples reveal 100% sensitivity and specificity with a limit of detection of 105 cfu/mL. The nanomaterial developed was found to be stable for more than 90 days at accelerated conditions. The developed device can be a screening tool for home-based or clinical assessment and follow the treatment accordingly, reducing exposure to broad-spectrum antibiotics in the case of nonbacterial infections.

Nanotechnology Approaches for Rapid Detection and Theranostics of Antimicrobial Resistant Bacterial Infections.

As declared by WHO, antimicrobial resistance (AMR) is a high priority issue with a pressing need to develop impactful technologies to curb it. The rampant and inappropriate use of antibiotics due to the lack of adequate and timely diagnosis is a leading cause behind AMR evolution. Unfortunately, populations with poor economic status and those residing in densely populated areas are the most affected ones, frequently leading to emergence of AMR pathogens. Classical approaches for AMR diagnostics like phenotypic methods, biochemical assays, and molecular techniques are cumbersome and resource-intensive and involve a long turnaround time to yield confirmatory results. In contrast, recent emergence of nanotechnology-assisted approaches helps to overcome challenges in classical approaches and offer simpler, more sensitive, faster, and more affordable solutions for AMR diagnostics. Nanomaterial platforms (metallic, quantum-dot, carbon-based, upconversion, etc.), nanoparticle-based rapid point-of-care platforms, nano-biosensors (optical, mechanical, electrochemical), microfluidic-assisted devices, and importantly, nanotheranostic devices for diagnostics with treatment of AMR infections are examples of rapidly growing nanotechnology approaches used for AMR management. This review comprehensively summarizes the past 10 years of research progress on nanotechnology approaches for AMR diagnostics and for estimating antimicrobial susceptibility against commonly used antibiotics. This review also highlights several bottlenecks in nanotechnology approaches that need to be addressed prior to considering their translation to clinics.

Core-shell nanoparticles as platform technologies for paper based point-of-care devices to detect antimicrobial resistance.

Globally, rapid development of antibiotic resistance amongst pathogens has led to limited treatment options and high indirect costs to health management. There is a need to avoid misuse of available antibiotics and to develop rapid, affordable and accessible diagnostic technologies to detect drug resistance even in resource limited settings. This study reports the development of instrument-free point-of-care devices for detection of antibiotic resistance for rapid diagnosis of drug resistance in the penicillin, cephalosporin and carbapenem groups of antibiotics. The simple paper-based devices for flow through assay determine the presence of resistant bacteria in a sample by a visible colour change within 30 minutes. At the center of this technology is the unique sensing nanomaterial comprising of core-shell nanoparticles layered with specific antibiotics. The core is comprised of chitosan nanoparticles of size ∼15 nm coated with the starch-iodine indicator to form a shell increasing the size to ∼47 nm. The test strip is coated with the nanoparticles, air-dried and overlayed with the required antibiotic. In the presence of penicillin, cephalosporin and carbapenem resistant bacteria, the core-shell nanoparticles undergo a visible colour change from blue to white. The core-shell nanoparticles were deposited on paper to form a point-of-care device. Devices were developed to screen for three main classes of antibiotics namely penicillins, cephalosporins and carbapenems. The devices were validated using standard resistant and susceptible ATCC strains in three different sample types, pure colony, broth culture and saline suspensions. The change of colour from blue to white was considered a positive test. The time of detection was found to be 30 min, while the limit of detection was 105 cfu ml-1. The device exhibited 100% sensitivity and specificity with known resistant and susceptible cultures not only from pure colonies but also from direct samples of spiked saline suspensions with graded confounding factors of albumin, glucose, and urea. The inter-device reproducibility and storage stability of the devices was established. The developed point-of-care devices have potential as screening devices for antimicrobial resistance.