Showing papers by "Enakshi Bhattacharya published in 2019"

Sensor for Continuous and Real-Time Monitoring of Biomolecule Permeation Through Ultrathin Silicon Nanoporous Membranes

Abstract: The increase in demand for continuous and real-time monitoring of permeation of biomolecules is addressed by using highly selective ultrathin silicon nanoporous membranes (SNMs) combined with detection using ultraviolet absorption. The membranes, with an average pore size of 8.8 nm, are fabricated using semiconductor batch processes including chemical vapor deposition and rapid thermal annealing. Bovine serum albumin (BSA) of a concentration of $250~\mu \text{g}$ /ml is used as the test molecule. The concentration of BSA diffused through the membrane is measured using optical transduction based in-house developed sensor. The photocurrent obtained from the sensor is measured every 15 min and compared with the standard Bradford assay at the same time-stamp. The concentration estimated by the sensor is found to agree with the Bradford assay with a standard deviation of 1.4%. The throughput of the membrane is increased by fabricating an array of SNMs, which showed an increase in diffusion rate by 3.8 times with respect to the single SNM. The clogging of pores by the biomolecules is analyzed using ionic conductivity experiments. The structural integrity of BSA diffused through the SNM is also analyzed.

Detection of Urea and Ammonia with Aluminium Coated Polysilicon Nanoresonators

Abstract: Aluminium coated polysilicon (Al-polySi) nanoresonator has been used to design a urea biosensor. The etching characteristic of Al by the ammonium hydroxide from urea hydrolysis in the presence of urease was used to estimate the urea concentration. Urease immobilized on Al coated polySi indicated smoothening of the surface with increasing urea concentration, confirming the etching of Al. The nanoresonator could estimate between 10-1000 nM concentrations of urea. The sensing was not affected in the presence of interferents such as uric acid and ascorbic acid, thus making it specific for urea. The sensor was found to be highly sensitive and specific and can have potential application in the field of medical diagnostics and environmental monitoring.