Detection and analysis of rotavirus in clinical stool samples using silver nanoparticle functionalized paper as SERS substrate.

Among the different analytical techniques, surface-enhanced Raman scattering (SERS) approach is a widely used technique for the detection and analysis of various chemicals and biological samples. Present study reports a low-cost, sensitive SERS substrate that has an ability to detect rotavirus in clinical stool samples. The proposed SERS substrate has been fabricated through drop-casting of silver nanoparticles (AgNPs) on a printing-grade paper. Rotavirus particles were extracted from clinical stool samples. The presence of rotavirus antigen in stool samples was confirmed using enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and sequencing. The characteristic Raman peaks of rotavirus (RV) particles in solution were found to be significantly enhanced when Raman signals were recorded from the paper-based SERS substrates. Using the proposed SERS substrate, rotavirus samples with concentration as low as 1% could be reliably recorded by the Raman spectrometer. The paper SERS substrate reported herein is an extremely cost-efficient platform and may find applications in other research and clinical laboratories as well.

Design, fabrication and testing of 3D printed smartphone-based device for collection of intrinsic fluorescence from human cervix.

Fluorescence spectroscopy has the potential to identify discriminatory signatures, crucial for early diagnosis of cervical cancer. We demonstrate here the design, fabrication and testing of a 3D printed smartphone based spectroscopic device. Polarized fluorescence and elastic scattering spectra are captured through the device using a 405 nm laser and a white LED source respectively. The device has been calibrated by comparison of spectra of standard fluorophores (Flavin adenine dinucleotide, fluorescein, rhodamine, and porphyrin) with the corresponding spectra collected from a commercial spectrometer. A few cervical tissue spectra have also been captured for proof of its applicability as a portable, standalone device for the collection of intrinsic fluorescence spectra from human cervix.

An affordable, handheld multimodal microscopic system with onboard cell morphology and counting features on a mobile device.

Microscopes, bright-field (BF) and fluorescence microscopes, in particular, are ubiquitous for clinical diagnostics, cellular and microbiological investigations and in research laboratories. However, the size, cost, fragility and need for skilled personnel to operate these tools restrict their use in resource-limited settings. As an alternative platform, herein, we report a flexible multimodal imaging system that operates in BF and fluorescence modes using a smartphone. Our device utilizes the inbuilt primary camera of phones, and with the aid of easily available optical components, the designed platform is transformed into a high-throughput microscopic device that performs on par with that of a laboratory-grade microscope. The designed platform operates at three different optical magnifications and yields a lateral resolution of 1.21 µm over an acceptable field-of-view (FoV) of diameter ∼4530 µm. The versatility of the device has been demonstrated through imaging of standard microbeads and human blood samples both in BF and fluorescence modes of imaging. Furthermore, the designed imaging platform is equipped with an on-board cell recognition feature which has been obtained through developing a smartphone application for automatic cell counting with high precision.

Turbidimetric analysis of growth kinetics of bacteria in the laboratory environment using smartphone.

For different microbiological and pathological studies, it is often required to monitor the growth of bacteria in a cultured medium in the laboratory environment. UV-VIS spectrophotometer is commonly used to estimate the growth of bacterial cell population by measuring the absorbance at 600 nm over a period of time. Colony-forming unit (CFU) is another approach, which has been routinely performed to estimate the live bacterial cells on semisolid agar plates. Herein, we demonstrate an alternative yet highly reliable sensing platform on a smartphone using which growth kinetics of different bacteria can be reliably monitored. The performance of the proposed smartphone sensor has been compared with the data obtained from OD600 and CFU analysis. A good correlation of bacterial growth rates enumerated based on the proposed smartphone sensor, bench-top spectrophotometer and CFU analysis have been observed under the experimental conditions.