Fabrication and characterisation of high performance polypyrrole modified microarray sensor for ascorbic acid determination

In this study, gold microelectrode array (Au/MEA) with electrode of 12 μm diameter was fabricated by photolithography technique. Subsequently, polypyrrole (Ppy) modified gold microarrays sensor (Ppy/Au/MEA) was prepared by cyclic voltammetry technique. The deposition potential range and number of cycles were optimised in order to get optimum thickness of Ppy film. Scanning Electron Microscope and Atomic Force Microscope investigations reveal that Ppy coating formed at 3 cycles is porous with thickness of 1.5 μm which exhibiting high catalytic current for ascorbic acid (AA) in square wave technique (SWV). In contrast to earlier sensors designs, these Ppy/Au/MEA sensors exhibits lower detection limit (LOD) of 10 nm towards AA at physiological conditions. It also exhibits enhanced sensitivity (2.5 mA cm⁻² mM⁻¹) and long range of linear detection limit from 10 nm to 2.8 mM. In the same way, polypyrrole modified macro Au (Ppy/Au/MA) biosensor was also fabricated and its electro catalytic property towards AA was compared with that of Ppy/Au/MEA. The Ppy/Au/MA exhibits sensitivity of only 0.27 mA cm⁻² mM⁻¹, LOD of 5 μM and linear range of 10 μM to 2.2 mM. Hence, our investigations indicate that the Ppy/Au/MEA could serve as highly sensitive sensor for AA than any of the earlier designs. So, the Ppy/Au/MEA electrode was utilised for determination AA in a wide variety of real samples.     

Monte Carlo simulations of antibody adsorption and orientation on charged surfaces

Monte Carlo simulations were performed to study the adsorption and orientation of antibodies on charged surfaces based on both colloidal and all-atom models. The colloidal model antibody consists of 12 connected beads representing the 12 domains of an antibody molecule. The structure of the all-atom antibody model was taken from the protein databank. The effects of the surface charge sign and density, the solution pH and ionic strength on the adsorption and orientation of different colloidal model antibodies with different dipole moments were examined. Simulation results show that both the 12-bead and the all-atom models of the antibody, for which the dipole moment points from the Fc to (Fab)2 fragments, tend to have the desired "end-on" orientation on positively charged surfaces and undesired "head-on" orientation on negatively charged surfaces at high surface charge density and low solution ionic strength where electrostatic interactions dominate. At low surface charge density and high solution ionic strength where van der Waals interactions dominate, 12-bead model antibodies tend to have "lying-flat" orientation on surfaces. The orientation of adsorbed antibodies results from the compromise between electrostatic and van der Waals interactions. The dipole moment of an antibody is an important factor for antibody orientation on charged surfaces when electrostatic interactions dominate. This charge-driven protein orientation hypothesis was verified by our simulations results in this work. It was further confirmed by surface plasmon resonance biosensor and time-of-flight secondary ion mass spectrometry experiments reported elsewhere.     

Synthesis and Platinum Complexes of an Alane‐Appended 1,1′‐Bis(phosphino)ferrocene Ligand

An aryldimethylalane‐appended analogue of 1,1′‐bis(diphenylphosphino)ferrocene, FcPPAl, was prepared, and reaction with [Pt(nb)₃] (nb=norbornene) afforded [Pt(η²‐nb)(FcPPAl)] ( 1 ). Heating a solution of 1 to 80 °C resulted in crystallization of [{Pt(FcPPAl)}₂] ( 2 ), whereas treatment of 1 with C₂H₄, C₂Ph₂, H₂, or CO provided [PtL(FcPPAl)] [L=C₂H₄ ( 3 ), C₂Ph₂ ( 4 )], [PtH₂(FcPPAl)] ( 5 ), and [Pt(CO)(FcPPAl)] ( 6 ). In all complexes, the FcPPAl ligand is coordinated through both phosphines and the alane. Whereas 2 adopts a T‐shaped geometry at platinum, 3 – 5 are square‐pyramidal, and 6 is distorted square‐planar. The hydride and carbonyl complexes feature unusual multicenter bonding involving platinum, aluminum, and a hydride or carbonyl ligand.     

Computer‐aided Discovery of Potential Inhibitors for Transthyretin‐related Amyloidosis

Transthyretin (TTR) is a homotetrameric plasma protein associated with human amyloid diseases. Although Tafamidis has been recently approved for the treatment of TTR familial amyloid polyneuropathy (FAP), there is still a need for more effective drugs in the treatment of TTR amyloidosis diseases. In this study, a computer‐aided approach combining molecular docking, virtual screening and molecular dynamics (MD) simulations was employed to identify potent TTR amyloidosis inhibitors from National Cancer Institute (NCI), Maybridge and Asdi databases. A receptor‐specific scoring function was also developed using comparative binding energy (COMBINE) method to accurately predict the inhibitory activities for the selected compounds during virtual screening. The developed receptor‐specific scoring function demonstrated good predictive ability by yielding strong correlation coefficients between experimental activities and estimated activities for 32 training set and 9 test set compounds, respectively. Moreover, it was successfully applied to rank the candidate compounds from structure‐based virtual screening. Finally, three compounds (NSC220163, MFCD00276817 and SPB06319) were identified as potential leads, which exhibited higher predicted inhibitory activities and higher binding affinities in comparison to the Tafamidis. Our results further suggest that halogen bonding interaction plays a crucial role in stabilizing the TTR‐inhibitor complex. These results indicate that our computational approach could effectively discover more potent TTR amyloidosis inhibitors, which can be further validate by in vitro and in vivo biological tests.     

Optimization of L-Lactic acid production from glucose by Rhizopus oryzae ATCC 52311

The effect of nutrients on L(+)-lactic acid production from glucose was investigated using Rhizopus oryzae ATCC 523 11. From the shake-flask experiments, the optimal medium composition was defined for improved lactic-acid production. In order to enhance lactic-acid production rate and product yield, controlled aeration in a bubble column was conducted under optimal conditions. Results showed a maximum lactic-acid production rate of 2.58 g/L/h was obtained with an initial glucose concentration of 94 g/L. Finallactic-acid concentration of 83 g/L was achieved after 32 h of fermentation with a weight of 0.88 glactic acid/g glucose consumed.