Paper microchip with a graphene-modified silver nano-composite electrode for electrical sensing of microbial pathogensElectronic supplementary information (ESI) available. See DOI: 10.1039/c6nr06417e

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 10 6 and 10 8 copies per ml, and (ii) amplified HIV-1 nucleic acids in samples with viral loads between 10 fg μl −1 and 10 8 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 10 8 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. Paper-based point-of-care microchips can shift the paradigm in the management of infectious diseases.