Paper microchip with a graphene-modified silver nano-composite electrode for electrical sensing of microbial pathogens

Abstract

Rapid and sensitive point-of-care diagnostics are of paramount importance for early detection of infectious diseases and timely initiation of treatment. Here, we present cellulose paper and flexible plastic chips with printed graphene-modified silver electrodes as universal point-of-care diagnostic tools for the rapid and sensitive detection of microbial pathogens or nucleic acids through utilizing electrical sensing modality and loop-mediated isothermal amplification (LAMP). We evaluated the ability of the developed paper-based assay to detect (i) viruses on cellulose-based paper microchips without implementing amplification in samples with viral loads between 106 and 108 copies per ml, and (ii) amplified HIV-1 nucleic acids in samples with viral loads between 10 fg µl−1 and 108 fg µl−1. The target HIV-1 nucleic acid was amplified using the RT-LAMP technique and detected through the electrical sensing of LAMP amplicons for a broad range of RNA concentrations between 10 fg µl−1 and 108 fg µl−1 after 40 min of amplification time. Our assay may be used for antiretroviral therapy monitoring where it meets the sensitivity requirement of the World Health Organization guidelines. Such a paper microchip assay without the amplification step may also be considered as a simple and inexpensive approach for acute HIV detection where maximum viral replication occurs.

Label-free electrical sensing of bacteria in eye wash samples: A step towards point-of-care detection of pathogens in patients with infectious keratitis

“…Electrical sensing is a powerful modality that can be used for the development of microfluidic-based platforms for target cells or pathogen sorting and detection (Shafiee et al 2009; Shafiee et al 2010, Shafiee et al 2015, Safavieh et al 2016). Electrical sensing-based methods through impedance magnitude measurement of intact bacteria captured on interdigitated electrodes usually requires high concentration of bacteria on the surface of electrodes in order to generate a detectable electrical sensing (Dastider et al, 2015).…”

“…Among the various sensing modalities used in the development of biosensors for bacteria detection, impedance spectroscopy has shown great promise due to its simplicity, low-cost, portability, and adaptability to multiplexing (Boehm et al 2007; Gibson et al 1992). It has been used in developing biosensors for virus detection as well (Shafiee et al 2013; Shafiee et al 2015; Safavieh et al 2016). The impedance-based sensing mechanisms developed by others are based on the detection of signal changes due to binding target bacteria on the surface of a functionalized electrode.…”

Rapid Real-Time Antimicrobial Susceptibility Testing with Electrical Sensing on Plastic Microchips with Printed Electrodes

“…From our previous studies, 9,30,31 we found that the change in the impedance is maximum at 1 kHz. Additionally, we found a high signal-to-noise ratio for 1 kHz.…”

Recent advances in lab-on-a-chip technologies for viral diagnosis

“…They immobilized gold nanoparticles and detect probe conjugates on a nitrocellulose membrane for the LFS layer to capture target amplicons. (G) Integrated paper-based chip for LAMP products detection by electrical conductivity measurement (Safavieh et al, 2017). (Zhu et al, 2020).…”

“…The pH value change is not obviously caused by the solution condition and small volume. 5G) was used for the electrical conductivity measurement integrated with LAMP for HIV detection (Safavieh et al, 2017). 5F).…”