Ashok Mulchandani

University of California, Riverside

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Wilfred Chen

University of Delaware

174

Nosang V. Myung

University of Notre Dame

Priti Mulchandani

University of California, Riverside

Joseph Wang

University of California, San Diego

John H. T. Luong

University College Cork

Mangesh A. Bangar

Applied Materials (United States)

Pankaj Ramnani

University of California, Riverside

Marc A. Deshusses

Duke University

Mahendra D. Shirsat

Dr. Babasaheb Ambedkar Marathwada University

Marylynn V. Yates

University of California, Riverside

Cooperative Institutions

University of California, Riverside

201

Chinese Academy of Sciences

University of California System

Arizona State University

John Wiley & Sons (United States)

Bioengineering Center

CSIR National Physical Laboratory of India

Riverside

Council of Scientific and Industrial Research

National Center for Genetic Engineering and Biotechnology

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MoS2-graphene heterostructures as efficient organic compounds sensing 2D materials

Carbon (2018)

Tung Pham Pankaj Ramnani Claudia C. Villarreal Jhoann Lopez Protik Das

Molybdenum disulfide

Ultraviolet photoelectron spectroscopy

10.1016/j.carbon.2018.10.079

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Citations (56)

Molecular beacon–quantum dot–Au nanoparticle hybrid nanoprobes for visualizing virus replication in living cells

Chemical Communications (2010)

Hsiao-Yun Yeh Marylynn V. Yates Ashok Mulchandani Wilfred Chen

Here we describe a new hybrid fluorescent nanoprobe composed of a nuclease-resistant molecular beacon (MB) backbone, CdSe-ZnS core-shell quantum dots (QDs) as donors, and gold nanoparticles (Au NPs) as quenchers, for the real-time visualization of virus replication in living cells. By using a Au NP-MB to QD ratio of 6 : 1, a 7.3-fold increase in fluorescent signal was achieved upon target binding. For living cell experiments, a hexahistidine-appended Tat peptide was self-assembled onto the QD surface to provide nearly 100% non-invasive delivery of the QD-MB-Au NP probes within 2 h. By directly visualizing the fluorescent complexes formed with the newly synthesized viral RNA, this QD-MB-Au NP probe provided sensitive and real-time detection of infectious viruses as well as the real-time visualization of cell-to-cell virus spreading.

Nanoprobe

Molecular beacon

10.1039/c001553a

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Citations (76)

Effect of Al2O3 Passive Layer on Stability and Doping of MoS2 Field-Effect Transistor (FET) Biosensors

Biosensors (2021)

Tung Pham Ying Chen Jhoann Lopez Mei Yang Thien‐Toan Tran

Molybdenum disulfide (MoS

Molybdenum disulfide

Degradation

10.3390/bios11120514

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Citations (8)

Single Polypyrrole Nanowire Ammonia Gas Sensor

Electroanalysis (2007)

Sandra C. Hernández Debangshu Chaudhuri Wilfred Chen Nosang V. Myung Ashok Mulchandani

Abstract We report the synthesis, electrical characterization and ammonia gas sensing with single nanowire of conducting polypyrrole. Three hundred nanometer in diameter and 50 to 60 μm long polypyrrole nanowires were synthesized by chemical polymerization inside SiO 2 coated alumina membranes. Temperature dependent electrical resistance studies established that the chemically synthesized nanowires were more ordered compared to electrochemically synthesized nanowires. We further demonstrated that gas sensors based on single polypyrrole nanowire exhibited good sensitivity towards ammonia, and provided a reliable detection at concentration as low as approximately 40 ppm.

Polypyrrole

Ammonia gas

Nanometre

10.1002/elan.200703933

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Citations (175)

Laser-etched grooves for rapid fluid delivery for a paper-based chemiresistive biosensor

Biosensors and Bioelectronics (2021)

Sidharth Modha Yu Shen Hussein Chamouni Ashok Mulchandani Hideaki Tsutsui

Sample Preparation

10.1016/j.bios.2021.113090

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Citations (27)

Capillary Electrophoresis Microchips for Separation and Detection of Organophosphate Nerve Agents

Analytical Chemistry (2001)

Joseph Wang Madhu Prakash Chatrathi Ashok Mulchandani Wilfred Chen

A miniaturized analytical system for separating and detecting toxic organophosphate nerve agent compounds, based on the coupling of a micromachined capillary electrophoresis chip with a thick-film amperometric detector, is described. Factors influencing the on-chip separation and detection processes have been optimized. Using a MES buffer (20 mM, pH 5.0) running buffer, a 72-mm-long separation channel, and a separation voltage of 2000 V, baseline resolution is observed for paraoxon, methyl parathion, fenitrothion, and ethyl parathion in 140 s. Such miniaturization and speed advantages are coupled to submicromolar detection limits and good precision. Applicability to spiked river water samples is demonstrated, and the implications for on-site environmental monitoring and rapid security screening/warning are discussed.

Paraoxon

Amperometry

Parathion

Parathion methyl

Fenitrothion

10.1021/ac001424e

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Citations (151)

Synthesis of gold nanostructures using glycine as the reducing agent

Nanotechnology (2020)

Joun Lee Sanggon Kim Syed Mubeen Ashok Mulchandani Wilfred Chen

Biological synthesis of gold nanostructures could potentially offer an environmentally friendly alternative to traditional chemical synthetic methods. During the last decades, various biomolecules, including amino acids, have been successfully used as reducing and capping agents to synthesize multi-shaped gold nanostructures. A grand challenge in this field is to increase our ability to control the size and shape of gold nanostructures formed precisely by systematic synthetic approaches based on the understanding of the mechanism for structural determination. In this study, using glycine as the model amino acid and chloroaurate (AuCl4-) ions as the precursor solution, we report the finding that the shape of the gold nanostructures synthesized showed a strong correlation with the speciation of gold complexes determined by the pH, precursor concentration and chloride concentration of the solvent system. The gold chloro-hydroxy speciation [AuClx(OH)4-x]- (with x = 0-4) influenced the shape of the gold nanostructures formed, with gold nanoplatelets, nanotriangles, nanokites and nanoribbons observed at x = 4, 3, 2 and 1, respectively, and spherical nanoparticles observed at x = 0. Glycine was found to play a role as a reducing agent, but no significant effect on the morphology was observed, indicating the dominance of gold chloro-hydroxy speciation in the structural formation. These results collectively provide synthetic considerations to systematically synthesize non-spherical to spherical biosynthesized gold nanostructures by controlling the speciation of [AuClx(OH)4-x]-.

Biomolecule

Reducing agent

10.1088/1361-6528/abaa76

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Citations (9)

Affinity purification of plasmid DNA by temperature‐triggered precipitation

Biotechnology and Bioengineering (2003)

Jan Košťál Ashok Mulchandani Wilfred Chen

Abstract This report describes a new plasmid DNA purification method, which takes advantage of the DNA‐binding affinity and specificity of the bacterial metalloregulatory protein MerR, and of the temperature responsiveness of elastin‐like proteins (ELPs). Upon increasing the temperature, ELP undergoes a reversible phase transition from water‐soluble forms into aggregates, and this property was exploited for the precipitation of plasmid DNA containing the MerR recognition sequence by a simple temperature trigger. In one purification step, plasmid DNA was purified from E. coli cell lysates to a better purity than that prepared by a standard alkaline purification method, with no contaminating chromosomal DNA and cellular proteins. This protein‐based approach, in combination with the reversible phase transition feature of ELP, makes the outlined method a promising candidate for large‐scale purification of plasmid DNA for sensitive applications such as nonviral gene therapy or DNA vaccines. © 2004 Wiley Periodicals, Inc.

Plasmid preparation

Exogenous DNA

10.1002/bit.10890

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Citations (32)

Hybrid ZnO/SWNT Nanostructures Based Gas Sensor

Electroanalysis (2012)

Sandra C. Hernández James Kakoullis Jae Hong Lim Syed Mubeen Carlos M. Hangarter

Abstract Zinc oxide (ZnO) nanoparticles decorated single walled carbon nanotubes (SWNTs) were electrochemically synthesized where the deposition conditions were systematically explored to tailor the size, density, and microstructure of the ZnO nanoparticles and correlated to the gas sensing performance. Room temperature conductometric detection of various analytes including CO, CO 2 , NO 2 , NH 3 , SO 2 , H 2 S with ZnO/SWNT hybrid nanostructures demonstrated uncharacteristic selectivity towards H 2 S with little to no response for the other analytes examined. Optimal ZnO/SWNTs gas sensor devices showed a significantly increased in H 2 S sensitivity over unfunctionalized SWNT networks (i.e. 4.96 % per ppm V vs. 0.225 % ppm V ) with a lower detection limit in the ppb range. Additionally, the H 2 S sensing performance was greatly improved by enhancing the crystallinity of ZnO nanoparticles.

10.1002/elan.201200135

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Citations (22)

Aptamer-based Biosensor for Environmental Monitoring

The Royal Society of Chemistry eBooks (2011)

Lakshmi N. Cella Wilfred Chen Ashok Mulchandani

Since their discovery, aptamers have captivated the attention of researchers. Today aptamers are available for a wide variety of target molecules ranging from metal ions to whole cells. In this chapter the description of aptamer production and of their interesting properties for biosensing are reported. Applications to environmental monitoring, such as detection of pathogens, toxins, drugs, and organic and inorganic pollutants, are also illustrated.

Aptamer

10.1039/bk9781849731317-00061

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Citations (0)