Flower-like MoS2 modified with carbon nanospheres (CNS) displays energy-storage capability when used as an aqueous symmetric pseudocapacitor.

Mesoporous molybdenum disulfide (MoS 2 ) with different morphologies have been prepared via hydrothermal method using different solvents, water or water/acetone mixture. The MoS 2 obtained with water alone gave a graphene-like nanoflakes (g-MoS 2 ) while the other with water/acetone (1:1 ratio) gave a hollow-like morphology (h-MoS 2 ). Both materials are modified with carbon nanospheres as conductive material and investigated as symmetric pseudocapacitors in aqueous electrolyte (1 M Na 2 SO 4 solution). The physicochemical properties of the MoS 2 layered materials have been interrogated using the surface area analysis (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, fourier-transform infrared (FTIR) spectroscopy, and advanced electrochemistry including cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), repetitive electrochemical cycling tests, and electrochemical impedance spectroscopy (EIS). Interestingly, a simple change of synthesis solvents confers on the MoS 2 materials different morphologies, surface areas, and structural parameters, correlated by electrochemical capacitive properties. The g-MoS 2 exhibits higher surface area, higher capacitance parameters (specific capacitance of 183 F g −1 , maximum energy density of 9.2 Wh kg −1 and power density of 2.9 kW kg −1 ) but less stable electrochemical cycling compared to the h-MoS 2 . The findings show promises for the ability to tune the morphology of MoS 2 materials for enhanced energy storage. One of the factors that determine the performance of any energy material, be it in catalysis, sensing, photochemistry or electric energy storage, is its morphology.1 This explains why different materials with different dimensions (zero-, one-, two-or threedimensional nanostructures) give different physico-chemical properties and applications.2 Morphology has effects on the surface area, kinetics and thermodynamic properties of the materials.3 For example, it is has been known that graphene and carbon nanotubes give different catalytic properties due to their morphologies. 4 Nanowires are known to enhance electron transport compared to nanoparticles of the same materials.

Graphical Abstract This work investigates how bovine serum albumin (BSA), a commonly used protein in the fabrication of electrochemical immunosensors, can impact on the sensitivity of detection when integrated with antibody (Ab) pre-encapsulated with (i) insulating polyacrylonitrile (PAN) fibre (i.e., GCE-PAN-Ab-BSA immunosensor) or (ii) conducting PAN-grafted iron (II) phthalocyanine (FePc) (i.e., GCE-PAN@FePc-Ab-BSA immunosensor), using Vibrio cholerae toxin as a case study bioanalyte. Both immunosensors show different charge-transfer kinetics that strongly impact on their immunosensitive detection. From the electrochemical data, GCE-PAN-Ab-BSA is more insulating with the presence of BSA, while the GCE-PAN@FePc-Ab-BSA is more conducting with BSA. The CV of the GCE-PAN-Ab-BSA is dominated by radial diffusion process, while that of the GCE-PAN@FePc-Ab-BSA is planar diffusion process. The behaviour of GCE-PAN@FePc-Ab-BSA has been associated with the facile coordination of BSA and FePc that permits co-operative charge-transport of the redox probe, while that of the GCE-PAN-Ab-BSA is related to the interaction-induced PAN-BSA insulating state that suppresses charge-transport. As a consequence of these different interaction processes, GCE-PAN-Ab-BSA immunosensor provides higher electroanalytical performance for the detection of Vibrio cholerae toxin (with sensitivity of 16.12 Ω/log [VCT, g/mL] and limit of detection (LoD) of 3.20 × 10 −13 g/mL compared to those of the GCE-PAN@FePc-Ab-BSA (4.16 Ω/log (VCT, g mL −1 ) and 2.00 × 10 −12 g/mL). The study confirms the need for a thorough understanding of the physico-chemistries of the electrode platforms for the construction of immunosensors. Although this work is on immunosensors for cholera infection, it may well apply to other immunosensors.

Human papillomavirus (HPV) is the causative agent for cervical cancer. Of the various types of HPV, the high-risk HPV-16 type is the most important antigenic high-risk HPV. In this work, the antigenic HPV-16 L1 peptide was immobilized on a glassy carbon electrode and used to detect several concentrations of the anti-HPV-16 L1 antibody, and vice versa. Two electrode platforms were used: onion-like carbon (OLC) and its polyacrylonitrile (OLC-PAN) composites. Both platforms gave a wide linear concentration range (1.95 fg/mL to 6.25 ng/mL), excellent sensitivity (>5.2 μA/log ([HPV-16 L1, fg/mL]), and extra-ordinarily low limit of detection (LoD) of 1.83 fg/mL (32.7 aM) and 0.61 fg/mL (10.9 aM) for OLC-PAN and OLC-based immunosensors, respectively. OLC-PAN modified with the HPV-16 L1 protein showed low LoD for the HPV-16 L1 antibody (2.54 fg/mL, i.e., 45.36 aM), proving its potential use for screening purposes. The specificity of detection was proven with the anti-ovalbumin antibody (anti-OVA) and native ovalbumin protein (OVA). An immobilized antigenic HPV-16 L1 peptide showed insignificant interaction with anti-OVA in contrast with the excellent interaction with anti-HPV-16 L1 antibody, thus proving high specificity. The application of the immunosensor as a potential point-of-care (PoC) diagnostic device was investigated with screen-printed carbon electrodes, which detected ultra-low (ca. 0.7 fg/mL ≈ 12.5 aM) and high (ca. 12 μg/mL ≈ 0.21 μM) concentrations. This study represents the lowest LoD reported for HPV-16 L1. It opens the door for further investigation with other electrode platforms and realization of PoC diagnostic devices for screening and testing of HPV biomarkers for cervical cancer.