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WOS:000414971100101 In this work, the structural features and sensor response toward ammonia of a three dimensional (3D) SWCNTs material covalently functionalised with 1,6-diethynylpyrene were studied. The target SWCNTs hybrid material was prepared by the reaction of azido substituted SWCNTs with 1,6-diethynylpyrene containing double terminal alkyne groups via the azide-alkyne Huisgen cycloaddition (Click) reaction. The structure of the 1,6-diethynylpyrene compound was determined by different spectroscopic methods such as FT-IR, H-1 NMR, MALDI-TOF mass and UV-vis, while its SWCNT-Pyrene 3D hybrid material was characterized by FT-IR, Raman, UV-vis spectroscopies and thermogravimetric analysis. The morphology of the hybrid films was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The sensing performance of the SWCNT-Pyrene 3D hybrid material was studied against low-concentrations of NH3 in the range of 0.1-40 ppm by measuring changes in the films' conductivity at different levels of relative humidity. The reversible electrical sensor response toward ammonia was observed both in the case of SWCNT and SWCNT-Pyrene 3D hybrid films, however the response values of SWCNT-Pyrene 3D hybrid film were higher than those of SWCNT. (C) 2017 Elsevier B.V. All rights reserved.

Herein, a novel one step synthesis of multicomponent three dimensional polyacrylic acid (PAA) based conducting hydrogel (CH) incorporated with iron phthalocyanine functionalised graphene nanoplatelets (GPL-FePc) is reported. An amperometric glucose biosensor was fabricated by the immobilization of glucose oxidase (GOx) onto the synthesised PAA-VS-PANI/GPL-FePc-CH (where VS-PANI is vinyl substituted polyaniline). Scanning electron microscopy reveals the presence of three dimensional microporous structure with estimated pore size of 19 μm. The 5-(trifluoromethyl)-2-mercaptopyridine substitution onto FePc enabled the solubility of FePc in water and controls the aggregation of GPL-FePc in the synthesised CH. A sharp peak around 699 nm in UV–visible spectra confirms the presence of incorporated GPL-FePc into CH. Cyclic voltammogram of the synthesised CH biosensor exhibited well defined redox peaks with a ΔEp value of 0.26 V in Fe(CN)6 3-/4- bench mark solution. The fabricated PAA-VS-PANI/GPL-FePc/GOx-CH amperometric biosensor resulted in remarkable detection sensitivity of 18.11 μA mM−1 cm−2 with an average response time of ∼1 s, linearity from 1 to 20 mM, and low detection limit of 6.4 μM for the determination of glucose.

Developing a biosensor capable of measuring glucose and other whole blood analytes for monitoring diabetes has been a major challenge for over four decades. In this thesis, an attempt has been made to develop three different novel metallophthalocyanine-based (MPcs) biosensors for this purpose. Three novel enzymatic biosensors have been fabricated to monitor glucose concentration and other whole blood analytes in vitro. The first fabricated biosensor is based on conducting multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc2/GOx-MFH) utilising reduced graphene oxide (rGO) and lutetium phthalocyanine (LuPc2) dissolved in chloroform to produce three-dimensional (3D) matrix as platform to enhance the sensing performance. Utilising the aqueous properties of a novel water-soluble iron phthalocyanine (FePc) derivative on the other hand, added more simplicity for the fabrication process of another biosensor (PAA-CP/GPL-FePc/GOx-CH) for enzymatic detection of glucose. Graphene nanoplatelets (GPL) have been attached non-covalently to the FePc resulting in a conducting hydrogel-based platform (CH). A third novel bioprobe (SiO2(LuPc2)-PANI(PVIA)/GOx-CNB) based on silica nanoparticles (SiO2) grafted polyaniline (PANI) has formed a conducting nanobeads (CNB)-based biosensor. The latter is employed as an enzymatic biosensor platform for the detection of glucose with enhanced sensitivity. Full characterisation has been carried out for all the raw studied materials as well as prepared biosensing platforms. UV-Visible and FT-IR spectroscopies as well as SEM, TEM, XRD, and EDX have been employed in order to help gaining full understanding of the nature and properties of the studied materials. The electrochemical properties of the newly developed biosensing platforms have been fully studied using common analytical methods such as cyclic voltammetry (CV), amperometry, and electrochemical impedance spectroscopy (EIS). The freeze dry system alongside the Brunauer-Emmett-Teller (BET) method were employed to characterise the surface area of the produced platforms.\ud The sensitivity of MFH biosensor studied in the range 2-12 mM of glucose is found to fall in the region of 15.31 μA mM−1 cm−2 with low detection limit of 25 μM. The biosensor based on CH platform exhibited a broad linear behaviour when glucose in the range 1-20 mM is studied, with high sensitivity of 18.11 μA mM−1 cm−2 and low detection limit of 1.1503 ng/mL. The conducting nanobeads-based biosensor (CNB) has led to a further improvement the sensitivity of glucose detection (38.53 μA mM−1 cm−2) with wide linear range of 1-16 mM and detection limit of 0.1 mM. All three biosensing platforms have exhibited excellent selectivity when examined against whole blood components.

The facile preparation of highly sensitive electrochemical bioprobe based on lutetium 13 phthalocyanine incorporated silica nanoparticles (SiO2(LuPc2)) grafted with Poly(vinyl 14 alcohol-vinyl acetate) itaconic acid (PANI(PVIA)) doped polyaniline conducting nanobeads 15 (SiO2(LuPc2)PANI(PVIA)-CNB) is reported. The preparation of CNB involves two stages (i) 16 pristine synthesis of LuPc2 incorporated SiO2 and PANI(PVIA); (ii) covalent grafting of 17 PANI(PVIA) onto the surface of SiO2(LuPc2). The morphology and other physico-chemical 18 characteristics of CNB were investigated. The scanning electron microscopy images show 19 that the average particle size of SiO2(LuPc2)PANI(PVIA)-CNB was between 180-220 nm. 20 The amperometric measurements showed that the fabricated SiO2(LuPc2)PANI(PVIA)-21 CNB/GOx biosensor exhibited wide linear range (1-16 mM) detection of glucose with a low 22 detection limit of 0.1 mM. SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor exhibited high 23 sensitivity (38.53 μA mM−1 cm−2) towards the detection of glucose under optimized 24 conditions. Besides, the real (juice and serum) sample analysis based on a standard addition 25 method and direct detection method showed high precision for measuring glucose at 26 SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor. The SiO2(LuPc2)PANI(PVIA)-CNB/GOx 27 biosensor stored under refrigerated condition over a period of 45 days retains ~ 96.4 % 28 glucose response current.

Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium Phthalocyanine (LuPc2) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc2/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, and VS-PANI through free radical polymerization using methylene bis-acrylamide, and ammonium persulphate as the cross linker and initiator. The LuPc2 was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc2-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc2-MFH and subsequently used for electrochemical detection of glucose. The PAA-rGO/VS-PANI/LuPc2/GOx-MFH biosensor exhibited high sensitivity (15.31 μA mM−1 cm−2) for the detection of glucose over a concentration range of 2–12 mM with a low detection limit of 25 µm. The PAA-rGO/VS-PANI/LuPc2-MFH biosensor showed a fast response time (1 s) to the addition of glucose with high storage stability of 3 months. The real sample analysis reveals that PAA-rGO/VS-PANI/LuPc2/GOx-MFH could be effectively used as an electrochemical biosensor in industrial as well clinical diagnosis.