Enhancing sensitivity of QCM for dengue type 1 virus detection using graphene-based polymer composites.

Graphene oxide-molecularly imprinted polymer composites (GO-MIP) have attracted significant attention as recognition materials in sensing due to their outstanding properties in terms of electrical and thermal conductivity, high mechanical modulus, and the comparably straightforward way to functionalize them. The aim of this study was to design a MIP-based sensor recognition material and enhance its sensitivity by blending it with GO for sensing a harmful dengue hemorrhagic fever pathogen, namely the dengue type 1 virus (DENV-1). Polymer composites comprising GO incorporated to an acrylamide (AAM)/methacrylic acid (MAA)/methyl methacrylate (MMA)/N-vinylpyrrolidone (VP) copolymer were synthesized and compared to the "pure" MIP, i.e., the copolymer without GO. The pure polymer revealed a zeta potential of + 9.9 ± 0.5 mV, whereas GO sheets prepared have a zeta potential of - 60.3 ± 2.7 mV. This results in an overall zeta potential of - 11.2 ± 0.2 mV of the composite. Such polymer composites seem appropriate to bind the positively charged DENV-1 particle (+ 42.2 ± 2.8 mV). GO-MIP coated onto 10-MHz quartz crystal microbalance (QCM) sensors indeed revealed two times sensitivity compared to sensors based on the pure MIP. Furthermore, GO-polymer composites revealed imprinting factors of up to 21, compared to 3 of the pure MIP. When plotting the sensor characteristic in a semilogarithmic way, the composite sensor shows the linear response to DENV-1 in the concentration range from 100 to 103 pfu mL-1. The corresponding limits of detection (S/N = 3) and quantification (S/N = 10) are 0.58 and 1.94 pfu mL-1, respectively. Furthermore, imprinted polymer composites selectively bind DENV-1 without significant interference: DENV-2, DENV-3, DENV-4, respectively, yield 13-16% of DENV-1 signal. The sensor requires only about 15-20 min to obtain a result.

An influenza A virus agglutination test using antibody-like polymers.

Antibodies are commonly used in diagnostic routines to identify pathogens. The testing protocols are relatively simple, requiring a certain amount of a specific antibody to detect its corresponding pathogen. Antibody functionality can be mimicked by synthesizing molecularly imprinted polymers (MIPs), i.e. polymers that can selectively recognize a given template structure. Thus, MIPs are sometimes termed 'plastic antibody (PA)'. In this study, we have synthesized new granular MIPs using influenza A virus templates by precipitation polymerization. The selective binding of influenza A to the MIP particles was assessed and subsequently contrasted with other viruses. The affinities of influenza A virus towards the MIP was estimated based on an agglutination test by measuring the amount of influenza subtypes absorbed onto the MIPs. The MIPs produced using the H1N1 template showed specific reactivity to H1N1 while those produced using H5N1 and H3N2 templates showed cross-reactivity.

A novel method for dengue virus detection and antibody screening using a graphene-polymer based electrochemical biosensor.

Dengue fever is a major disease that kills many people in the developing world every year. During early infection, a patient displays a high temperature without other signs. After this stage, and without proper treatment, serious damage to internal organs can happen, which occasionally leads to death. A rapid technique for the early detection of dengue virus (DENV) could reduce the number of fatalities. This study presents a new technique for the detection, classification and antibody screening of DENV based on electrochemical impedance spectroscopy (EIS). We found that the charge transfer resistance (Rct) of a gold electrode coated with graphene oxide reinforced polymer was influenced by virus type and quantity exposed on the surface. Molecular recognition capability established during the GO-polymer composite preparation was used to explain this observation. The linear dependence of Rct versus virus concentrations ranged from 1 to 2×103pfu/mL DENV with a 0.12 pfu/mL detection limit.