Sensitive detection of C-reactive protein using optical fiber Bragg gratings

An accurate and highly sensitive sensor platform has been demonstrated for the detection of C-reactive protein (CRP) using optical fiber Bragg gratings (FBGs). The CRP detection has been carried out by monitoring the shift in Bragg wavelength (Delta lambda(B)) of an etched FBG (eFBG) coated with an anti-CRP antibody (aCRP)-graphene oxide (GO) complex. The complex is characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. A limit of detection of 0.01 mg/L has been achieved with a linear range of detection from 0.01 mg/L to 100 mg/L which includes clinical range of CRP. The eFBG sensor coated with only aCRP (without GO) show much less sensitivity than that of aCRP-GO complex coated eFBG. The eFBG sensors show high specificity to CRP even in the presence of other interfering factors such as urea, creatinine and glucose. The affinity constant of similar to 1.1 x 10(10) M-1 has been extracted from the data of normalized shift (Delta lambda(B)/lambda(B)) as a function of CRP concentration. (C) 2014 Elsevier B.V. All rights reserved.

Multifunctional magnetic reduced graphene oxide dendrites: Synthesis, characterization and their applications

In this paper, for the first time, we have reported the novel synthesis of reduced graphene oxide (r-GO) dendrite kind of nanomaterial. The proposed r-GO dendrite possesses multifunctional properties in various fields of sensing and separation. The dendrite was synthesized by chemical reaction in different steps. Initially, the r-GO sheet was conjugated with silane group modified magnetic nanoparticle, resulting in nanoparticle decorated r-GO. The above r-GO sheet was further reacted with a new r-GO sheet, resulting in the formation of r-GO dendrite type of structure. Multifunctional behavior of this r-GO dendrite structure was studied by different methods. First, magnetic properties were studied by vibrating sample magnetometer (VSM) and it was found that dendrite structure shows good magnetic susceptibility (180.2 emu/g). The proposed r-GO dendrite also shows a very good antibacterial behavior for Escherichia coli and excellent electrochemical behavior towards ferrocyanide probe molecule. Along with these, it also acts as a substrate for the synthesis of molecularly imprinted polymer for europium metal ion, a lanthanide. The proposed imprinted sensor shows a very high selectivity and sensitivity for europium metal ion (limit of detection= 0.019 mu g L-1) in aqueous as well as real samples. (C) 2015 Elsevier B.V. All rights reserved.

Tailoring the interface in graphene/thermoset polymer composites: A critical review

With the emergence of scientific interest in graphene oxide (GO) in recent times, researchers have endeavored to incorporate GO in thermoset polymeric matrix to develop composites with extraordinary set of properties. The current state of research in graphene/thermoset polymer composites is highlighted here with a focus on the role of interface in dictating the overall properties of the composites. Different strategies like covalent and non-covalent functionalization of GO have been discussed with respect to improvement in mechanical, electrical, thermal and rheological properties. In addition, future prospects have been outlined. By assessing the current state of research in graphene/thermoset composites, it is obvious that graphene derivatives are promising materials in enhancing the structural properties of the nanocomposites at extremely low levels of filler loading. This opens new avenues in designing lightweight composites for myriad applications and by tailoring the interfacial adhesion with the polymer, ordered structure can be achieved at macroscopic processing scales. (C) 2015 Elsevier Ltd. All rights reserved.

A fluorescent molecularly-imprinted polymer gate with temperature and pH as inputs for detection of alpha-fetoprotein

In this work, we have reported a new approach on the use of stimuli-responsive molecularly imprinted polymer (MIP) for trace level sensing of alpha-fetoprotein (AFP), which is a well know cancer biomarker. The stimuli-responsive MIP is composed of three components, a thermo-responsive monomer, a pH responsive component (tyrosine derivative) and a highly fluorescent vinyl silane modified carbon dot. The synthesized AFP-imprinted polymer possesses excellent selectivity towards their template molecule and dual-stimuli responsive behavior. Along with this, the imprinted polymer was also explored as `OR' logic gate with two stimuli (pH and temperature) as inputs. However, the non-imprinted polymers did not have such `OR' gate property, which confirms the role of template binding. The imprinted polymer was also used for estimation of AFP in the concentration range of 3.96-80.0 ng mL(-1), with limit of detection (LOD) 0.42 ng mL(-1). The role of proposed sensor was successfully exploited for analysis of AFP in real human blood plasma, serum and urine sample. (C) 2015 Elsevier B.V. All rights reserved.