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The lyophilized biomass of bacterium Brevibacterium ammoniagenes was immobilized in polystyrene sulphonate-polyaniline (PSS-PANI) conducting polymer on a Pt twin wire electrode by potentiostatic electropolymerization. The bacterial cells retained their viability as well as urease activity under entrapped state, as confirmed with bacterial live-dead fluorescent assay and enzymatic assays. The entrapped cells were visualized using scanning electron microscope. The immobilized cells were used as a source of unpurified urease to develop a conductometric urea biosensor. The catalytic action of urease in the sensor released ammonia, thereby causing an increase in the pH of the microenvironment. The pH dependant change in the resistivity of the polymer was used as the basis of sensing mechanism. The sensor response was linear over a range of 0-75 mM urea with a sensitivity of 0.125 mM(-1). The sensor could be reused for 12-15 independent measurements and was quite stable in dry as well as buffered storage condition at 4 degrees C for at least 7 days.
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http://dx.doi.org/10.1016/j.bios.2009.01.024 | DOI Listing |
Clin Chim Acta
August 2025
Mehta Family School of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Khandwa Road, Indore 453552, Madhya Pradesh, India. Electronic address:
The current work focuses on the development and testing of point-of-care (POC) devices-based on a color sensor (CSD) and a fiber-optic spectrometer (FOS)-for healthcare monitoring of biological markers. Agarose-based fluorescent indicator-loaded thin film biosensors (TFBs) were synthesized by co-immobilizing analyte-specific enzymes such as glucose oxidase and urease. This study further evaluates enzyme-immobilized polymer-fluorophore-based thin films for the detection of glucose, urea, and pH in plasma and urine samples.
View Article and Find Full Text PDFAnal Chem
September 2025
State Key Laboratory of Chemo and Biosensing, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P.R. China.
is a major pathogen responsible for a wide range of infectious diseases in humans and is also the bacterium that causes the most deaths in children. Consequently, the rapid and accurate detection of is crucial for public health management. The IscB protein of the OMEGA (obligate mobile element-guided activity) system, as a programmable RNA-guided DNA endonuclease, shows high application potential for detecting single-nucleotide mismatches.
View Article and Find Full Text PDFEnzyme Microb Technol
December 2025
Department of Medicine, National Institute of Medical Sciences, NIMS University Rajasthan, Jaipur, India. Electronic address:
Herein, a urea biosensor and safe blood cleaning method utilizing a novel high throughput La-doped CeO nanosized artificial urease with high biocompatibility and enzyme-like activity were developed. The urease-like activity, stability composition, morphological characteristics, size, biocompatibility, and crystalline characteristics of the artificial urease were assessed. Considering its high urease-like activity, it is applied for both urea biosensing and safe blood cleaning.
View Article and Find Full Text PDFMikrochim Acta
July 2025
Department of Nanobiotechnology and Biomimetics School of Life Science Engineering College of Interdisciplinary Science and Technology, University of Tehran, P. O. Box: 14395-1561, Tehran, Iran.
A non-invasive, enzyme-based colorimetric biosensor was developed for urea detection in saliva, utilizing a growth-based method with Au@Ag core-shell nanostructures, including CTAB-coated gold nanoparticles (AuNPs) and CTAB-coated gold nanorods with short (SAuNRs) and high (HAuNRs) aspect ratios. The biosensing mechanism relies on urease-mediated hydrolysis of urea, which raises the pH and enhances the reduction capability of ascorbic acid, leading to the formation of a silver shell on the gold nanostructures, causing colorimetric changes correlated to urea concentration. A machine-learning comparative analysis was also performed to assess how the nanostructure morphology of AuNPs, SAuNRs, and HAuNRs affects sensor performance.
View Article and Find Full Text PDFBiosensors (Basel)
July 2025
Key Laboratory of Modern Agricultural Equipment and Technology, Ministry of Education, School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China (Y.H.).
Diuron (DU) is a widely used phenylurea herbicide designed to inhibit weed growth, but its high toxicity and prolonged half-life contribute significantly to environmental contamination. The majority of electrochemical (EC) sensors typically rely on a single response signal for the detection of DU, rendering them highly susceptible to interference from variable background noise in complex environments, thereby reducing the selectivity and robustness. By integrating molecularly imprinted polymer (MIP) with a ratiometric strategy, the aforementioned issues could be solved.
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