7 research outputs found
Targeted delivery of Doxorubicin conjugated to Folic acid and Vitamin E D-a-Tocopheryl Polyethylene glycol succinate (TPGS)
Master'sMASTER OF ENGINEERIN
Dual Functional Ultrafiltration Membranes with Enzymatic Digestion and Thermo-Responsivity for Protein Self-Cleaning
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 on to which trypsin was covalently immobilized. The enzyme immobilization density on the membrane surface decreased with increasing PNIPAAm concentration, due to the decreased number of amine functional sites. An ultrafiltration study was performed using the synthetic model solution containing BSA/NaCl/CaCl2, where the PNIPAAm containing biocatalytic membranes demonstrated a combined effect of enzymatic and thermo-switchable self-cleaning. The membrane without PNIPAAm revealed superior fouling resistance and self-cleaning with an RPD of 22%, compared to membranes with 2 and 4 wt % PNIPAAm with 26% and 33% RPD, respectively, after an intermediate temperature cleaning at 50 °C, indicating that higher enzyme density offers more efficient self-cleaning than the combined effect of enzyme and PNIPAAm at low concentration. The conformational volume phase transition of PNIPAAm did not affect the stability of immobilized trypsin on membrane surfaces. Such novel surface engineering design offer a promising route to mitigate surface⁻protein contamination in wastewater applications
Thermo-responsive nanofibrous composite membranes for efficient self-cleaning of protein foulants
Nanofiber composite membrane with intrinsic Janus surface for reversed-protein-fouling ultrafiltration
Janus
nanofiber based composite ultrafiltration (UF) membranes
were fabricated via a two-step method, i.e., consecutive electrospinning
of hydrophilic nylon-6,6/chitosan nanofiber blend and conventional
casting of hydrophobic poly(vinylidene difluoride) (PVDF) dope solution.
The as-developed PVDF/nylon-6,6/chitosan membranes were investigated
for its morphology using Scanning Electron Microscopy (SEM) by which
18 wt % PVDF was chosen as the optimum base polymer concentration
due to optimal degree of integration of cast and nanofiber layers.
This membrane was benchmarked against the pure PVDF and PVDF/nylon-6,6
membranes in terms of surface properties, permeability, and its ability
to reverse protein fouling. The improved hydrophilicity of the PVDF/nylon-6,6/chitosan
membrane was revealed from the 72% reduction in the initial water
contact angle compared to the pure PVDF benchmark, due to the incorporation
of intrinsic hydrophilic hydroxyl and amine functional groups on the
membrane surface confirmed by FTIR. The integration of the nanofiber
and cast layers has led to altered pore arrangements offering about
93% rejection of bovine serum albumin (BSA) proteins with a permeance
of 393 L·m<sup>–2</sup>·h<sup>–1</sup>·bar<sup>–1</sup> in cross-flow filtration experiments; while the PVDF
benchmark only had a BSA rejection of 67% and a permeance of 288 L·m<sup>–2</sup>·h<sup>–1</sup>·bar<sup>–1</sup>. The PVDF/nylon-6,6/chitosan membrane exhibited high fouling propensity
with 2.2 times higher reversible fouling and 78% decrease in the irreversible
fouling compared to the PVDF benchmark after 4 h of filtration with
BSA foulants