A graphene-modified cellulose paper microchip for HIV detection

Abstract Rapid and inexpensive virus detection and quantification at the point -of -care is of paramount importance for HIV management in resource -limited settings . Here, we report on an eas y-to-fabricate, cellulose paper -based microchip with printed graphene -modified electrode s for rapid detection of HIV -1 through electrical sensing . We evaluated the effect of electrode material and geometry on the performance of the microchip to detect serially diluted , electrically conductive samples . We evaluated the optimized microchip with HIV -spiked samples . 1. Introduction Effective, rapid , and inexpensive detection of virus es in biological samples at the point -of -care (POC) is an urgent need for infectious disease detection and treatment monitoring in resource -limited settings . Of particular interest is the detection and quantificatio n of Human Immunodeficiency Virus (HIV) in fingerprick volume s of biological samples at the POC for early detection of the disease and treatment monitoring in developing countries . According to UNAIDS , 35.3 million people are HIV infected globally , of whic h 25.0 million of them (equivalent to 70% of total HIV patients) live in sub -Saharan African countries [1]. T he t otal medical expenditure for HIV/AIDS in 20 12 was 18.9 b US $ and it is estimated that the annual expense will reach 22 -24 b US $ by the end of 2015 [1] . Expanding access globally to antiretroviral therapy (A RT) has been highly effective in reducing mortality in developing countries, however, a significant percentage of HIV -infected individuals do not yet receive ART , and those who have access to the treatment may not receive an effective therapy due to limited access to the appropriate treatment monitoring assays [2, 3] . Current rapid HIV tests, including OraQuick HIV test, lack the ability to detect HIV infection in the early stage as they d etect antibodies utilizing the principles of enzyme -linked immunosorbent assay (ELISA) and lateral flow test (LFT) . Further, these tests cannot detect virological failure that is critical for treatment monitoring and diagnosis of ART failure . Antibodies against HIV -1 start to appear after 3 -8 weeks from the initial infection . HIV -infected individuals have the potential to be substantial sources for transmission of the infection at the acute stage, when maximum vir al replication takes place . Although nucle ic acid tests (NAT) provide sensitive and accurate results for HIV detection and viral load measurement, these assays are laboratory -based, expensive, time consuming, and require skilled personnel [3]. Microfluidics has shown great promise in developing diagnostic assays for disease detection and treatment monitoring at the POC [3, 4] . Electrical sensing also provides robust , sensitive, and rapid detection of analytes in biological samples without the need for bulky equipment in optical -based sensing mechanisms [5 -11] . We have previously shown that electrical sensing modalit ies can be integrated with microfluidics to detect viruses in HIV -spiked samples [5, 10] . HIV was captured and isolated from samples off -chip using magnetic beads conjugated with ant i gp -120 antibody , and captured viruses were detected on -chip through electrical sensing of viral lysate . Here, for the first time, we present a cellulose paper -based microchip with printed graphene/silver electrodes for on -chip HIV capture and detection u sing electrical sensing of viral lysate.