Abstract
In this work we have developed a novel rGO-MWCNT (reduced graphene oxide-multiwalled carbon nanotube) nanocomposite material with Poly-L-Lysine functionalization which can be used for detection of biomolecules with enhanced sensitivity. The reduced GO sheets are found to play a major role as a connector and helps in the assembly of bundles of carbon nanotubes (CNTs) which may sometime play a role of upstanding nanostructures. The overall composite structure is further fully functionalized resulting in an overall high density of amino groups that can be used to capture biomolecules. The sensitivity of the as synthesized film is tested by the oxidation of cholesterol through cholesterol oxidase enzyme that is biochemically immobilized over these composite films. The test for the immobilization density of the novel films are carried out by mounting these films on sensitive thin section static micro/nano-cantilever platforms. The platforms have capability to measure cholesterol traces in blood upto an extent of 100 femto molar through deflection /bending of the cantilevers due to surface reaction. The films developed show a promise of high immobilization density which is further confirmed through fluorescence studies using FITC labeling of functionalized MWCNT-PLL and rGO-PLL films respectively.
Highlights
Graphene and its different manifestations have always attracted a lot of attention worldwide among the sensor community[1,2]
Since the Cholesterol-Oxidase in presence of Cholesterol generates a peroxide reaction it is prudent to utilize the planarity of r-GO substrates and the high density structure of the carbon nanotubes (CNTs) sidewalls in conjunction while both are outlaid in composite form
Conclusions rGO-MWCNT-PLL composite films have been synthesized are evaluated for bindability to functional groups
Summary
Graphene and its different manifestations have always attracted a lot of attention worldwide among the sensor community[1,2]. Of significant mention is its high surface area and planarity which makes it the obvious choice for serving as a functional material and the backbone of many of the nano-composite forms of graphene family[3]. RGO sheets, have an overall high surface area needing to be formulated very carefully through proper interlayer separation Otherwise, they may pile up or irreversibly agglomerate to form graphite through the out of plane vander Waals forces or π-π stacking. The functionalized rGO-CNTs composites have been tested for their efficacy to detect trace concentrations of bio-analytes by using sensitive SU-8 micro-nanocantilevers and studying their deflection by tracing a beam of laser reflected from the top surface of the cantilever surface. While the functionalized films are seen to show maximum deflection, the functionalized planar rGO sheets or functionalized CNT as immobilized on the cantilever surface do not show the same limit of detection. An abundance of free amine groups on the CNTs and GO sheets play a very critical role for enhancing the sensitivity and lowering the limit of detection for cholesterol molecules
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