Papers by Anbharasi Vanangamudi
Controlling surface-protein interaction during wastewater treatment is the key motivation for dev... more Controlling surface-protein interaction during wastewater treatment is the key motivation for developing functionally modified membranes. A new biocatalytic thermo-responsive poly(vinylidene fluoride)(PVDF)/nylon-6,6/poly(N-isopropylacrylamide)(PNIPAAm) ultrafiltration membrane was fabricated to achieve dual functionality of protein-digestion and thermo-responsive self-cleaning. The PVDF/nylon-6,6/PNIPAAm composite membranes were constructed by integrating a hydrophobic PVDF cast layer and hydrophilic nylon-6,6/PNIPAAm nanofiber layer where trypsin enzymes were covalently immobilized. The immobilization density of enzymes on the membrane surface decreased with increasing PNIPAAm concentration, due to the decreased number of amine functional sites. Through a ultrafiltration study using a model solution containing BSA/NaCl/CaCl2, the PNIPAAm containing biocatalytic membranes demonstrated a combined effect of enzymatic and thermo-switchable self-cleaning. The membrane without PNIPAAm r...
ACS Applied Materials & Interfaces, 2018
A new biocatalytic nanofibrous composite ultrafiltration membrane was developed to reduce protein... more A new biocatalytic nanofibrous composite ultrafiltration membrane was developed to reduce protein fouling interactions and self-clean the membrane surface. The dual-layer poly(vinylidenefluoride)/nylon-6,6/chitosan composite membrane contains a hydrophobic poly(vinylidenefluoride) cast support layer and a hydrophilic functional nylon-6,6/chitosan nanofibrous surface layer where enzymes were chemically attached. The intrinsic surface chemistry and high surface area of the nanofibers allowed optimal and stable immobilization of trypsin (TR) and α-chymotrypsin enzymes via direct covalent binding. The enzyme immobilization was confirmed by X-ray photoelectron spectroscopy and visualized by confocal microscopy analysis. The prepared biocatalytic composite membranes were nanoporous with superior permeability offering stable protein antiadhesion and self-cleaning properties owing to the repulsive mechanism and digestion of proteins into peptides and amino acids, which was quantified by the gel electrophoresis technique. The TR-immobilized composite membranes exhibited 2.7-fold higher permeance and lower surface protein contamination with 3-fold greater permeance recovery, when compared to the pristine membrane after two ultrafiltration cycles with the model feed solution containing bovine serum albumin/NaCl/CaCl2. The biocatalytic membranes retained about 50% of the enzyme activity after six reuse cycles but were regenerated to 100% activity after enzyme reloading, leading to a simple and cost-effective water remediation operation. Such surface- and pore-engineered membranes with self-cleaning properties offer a viable solution for severe surface protein contamination in food and water applications.
ACS Applied Materials & Interfaces, 2017
Journal of Membrane Science, 2019
This study developed a self-clean thermo-responsive nanofibrous poly(vinylidene fluoride) (PVDF)/... more This study developed a self-clean thermo-responsive nanofibrous poly(vinylidene fluoride) (PVDF)/nylon-6,6/poly(N-isopropylacrylamide) (PNIPAAm) composite ultrafiltration membrane consisting of a nylon-6,6/PNIPAAm functional nanofibre layer integrated into a PVDF substrate. The morphological analysis showed the presence of electrospun nano-nets branching out from the main nanofibres as PNIPAAm concentration increased, affecting the pore size distribution and solute rejection. The PVDF/nylon-6,6/PNIPAAm membranes showed improved surface hydrophilicity below the low critical solution temperature (LCST) and strong thermo-switchability. With bovine serum albumin (BSA) as the model foulant, the rejection of the 4 wt% PNIPAAm membranes was greatly improved to above 96%. Through a two-cycle ultrafiltration study using feed solution containing BSA and CaCl2, the membrane with 4 wt% PNIPAAm showed superior recovery of water permeance up to 97% assisted with temperature-change cleaning, compared to the control membrane that only recovered 56%. Filtration experiments with and without intermediate temperature-change cleaning proved that the anti-fouling mechanism of the PNIPAAm membranes was strongly associated with surface wettability and rapid conformation of PNIPAAm polymer chains induced by volume-phase transition, resulting in reduced protein adsorption and 'shaking-off' of the absorbed proteins from the membrane surface. Such smart responsive membranes have great potential for the development of easy-to-clean membranes for food and wastewater treatment.
Chemical Engineering Journal, 2015
Macromolecular Materials and Engineering, 2014
Journal of Biomedical Materials Research Part A, 2010
This research developed a prodrug strategy to conjugate doxorubicin (DOX) to D-a-tocopheryl polye... more This research developed a prodrug strategy to conjugate doxorubicin (DOX) to D-a-tocopheryl polyethylene glycol succinate (TPGS) and folic acid (FOL) for targeted chemotherapy to enhance the therapeutic effects and reduce the side effects of the drug. We synthesized two conjugates, TPGS-DOX and TPGS-DOX-FOL, to quantitatively evaluate the advantages of TPGS conjugation and FOL conjugation through passive and active targeting effects. The successful conjugation was confirmed by 1 H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The in vitro drug release was found pH dependent, which is in favor of cancer treatment. The in vitro cellular uptake and cytotoxicity were evaluated with MCF-7 breast cancer cells. It was found that the cellular uptake of DOX increased 15.2% by TPGS conjugation and further 6.3% by FOL conjugation after 0.5-h cell culture. The IC 50 after 24-h cell culture with MCF-7 cancer cells showed that TPGS-DOX conjugate could be 1.19-fold effec-tive versus DOX and that TPGS-DOX-FOL could be 38.6-fold effective than TPGS-DOX and thus 45.0-fold more effective versus DOX. In vivo experiment showed that the half-life of TPGS-DOX and TPGS-DOX-FOL were increased 3.79-and 3.9-fold than the free DOX, and the area under the curve were increased 19.2-and 14.5-fold than the DOX, respectively. The biodistribution data showed that TPGS-DOX and TPGS-DOX-FOL significantly lowered drug accumulation in the heart, thereby reducing the cardiotoxicity, which is the main side effect of the DOX. Furthermore, TPGS-DOX can limit, and TPGS-DOX-FOL can further deduce, the gastrointestinal side effect of the drug. V C 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 94A: 730-743, 2010
Uploads
Papers by Anbharasi Vanangamudi