Rohit Teotia

The biocompatibility and separation performance of antioxidative polysulfone/vitamin E TPGS composite hollow fiber membranes.

The extended interaction of blood with certain materials like hemodialysis membranes results in the activation of cellular element as well as inflammatory response. This results in hypersensitive reactions and increased reactive oxygen species, which occurs during or immediately after dialysis. Although polysulfone (Psf) hollow fiber has been commercially used for acute and chronic hemodialysis, its biocompatibility remains a major concern. To overcome this, we have successfully made composite Psf hollow fiber membrane consisting of hydrophilic/hydrophobic micro-domains of Psf and Vitamin E TPGS (TPGS). These were prepared by dry-wet spinning using 5, 10, 15, 20 wt% TPGS as an additive in dope solution. TPGS was successfully entrapped in Psf hollow fiber, as confirmed by ATR-FTIR and TGA. The selective skin was formed at inner side of hollow fibers, as confirmed by SEM study. In vitro biocompatibility and performance of the Psf/TPGS composite membranes were examined, with cytotoxicity, ROS generation, hemolysis, platelet adhesion, contact and complement activation, protein adsorption, ultrafiltration coefficient, solute rejection and urea clearance. We show that antioxidative composite Psf exhibits enhanced biocompatibility, and the membranes show high flux and high urea clearance, about two orders of magnitude better than commercial hemodialysis membranes on a unit area basis.

Improved hemodialysis with hemocompatible polyethersulfone hollow fiber membranes: In vitro performance

We show that addition of nanozeolite (NZ) and vitamin E D-α-Tocopherol polyethylene glycol succinate (TPGS or T) considerably improves the performance of polyethersulfone (PES or P) hollow fiber membrane (HFM) for hemodialysis. Nanocomposite HFMs were manufactured using PES as a polymer, TPGS as an additive and NZ as a filler to give a composite membrane called PT-NZ. HFMs were spun by dry-wet spinning principle based on liquid-liquid phase separation. TPGS and NZ were successfully incorporated in HFMs, as confirmed by EDX elemental mapping. The resultant PT-NZ HFMs had improved hemocompatibility: lower percent hemolysis (0.28% in batch mode and 0.32% in continuous mode), lower platelet adhesion, higher coagulation time and lower protein adsorption (16.34 µg/cm2 ), compared with P, PT, and commercial (F60S) HFMs. The ultrafiltration coefficient of PT-NZ HFM-based module (274.59 mL/m2 /h/mmHg) was ∼1.5-times higher than that of F60S membranes (151.67 mL/m2 /h/mmHg), and the solute rejection of both the membranes was comparable. The toxin clearance performance of lab-scale PT-NZ HFM-based hemodialyzer with uremic toxin spiked goat blood was remarkably higher (five times) than that of F60S. Hence, the synthesized PT-NZ HFMs are a potentially attractive membrane material for hemodialysis application, particularly due to decreased treatment time and minimal side reactions.

Coumarine–imino–C2-glucosyl conjugate as receptor for Cu2+ in blood serum milieu, on silica gel sheet and in Hep G2 cells and the characterization of the species of recognition

A coumarine-imino-C2-glucosyl conjugate (L) was synthesized and characterized. The conjugate L is found to recognize Cu(2+) in aqueous HEPES buffer by exhibiting a 95% fluorescence quenching in pH range 7-10 even in the presence of several biologically and ecologically relevant metal ions. Fluorescence on-off behavior has been clearly demonstrated on the basis of the binding variability of Cu(2+) to L. The binding has been elicited through the changes observed in fluorescence, absorption, ESI-MS and (1)H NMR titrations. All the other thirteen metal ions studied did not show any change in the fluorescence emission. These ions do not interfere with the recognition of Cu(2+) by L. The structural features of [CuL]2 complex in both the isomeric forms were established by DFT computational calculations. The utility of L has been demonstrated by showing its sensitivity toward Cu(2+) on a thin layer of silica gel. The L gives sensitive fluorescence signals for Cu(2+) even in blood serum and exhibits appropriate fluorescence responses in living cells.

Porosity and compatibility of novel polysulfone-/vitamin E-TPGS-grafted composite membrane

Polysulfone (Psf) hollow fiber membranes are widely used for hemodialysis. Despite its popularity as a biomaterial, the hydrophobicity of the polymer is a major concern for blood contact applications. Various blends of the polymer with hydrophilic ligands have been reported in the literature, to achieve desired surface property. To increase hydrophilicity, we report here a hydrophilic polysulfone polymer by covalently coupling vitamin E tocopheryl polyethylene glycol 1000 succinate (Vit E-TPGS or TPGS) and Psf. 1H NMR confirmed grafting of TPGS to Psf. With a high degree of TPGS substitution, the Psf-g-TPGS was completely hydrophilic, which resulted in no fiber formation alone. Hence, composite membranes were prepared by mixing plain Psf and Psf-g-TPGS in 1.8:1 ratio, which also resulted in a hydrophilic character. This can be tuned toward slightly hydrophilic with a higher ratio. The porosity and biocompatibility of the Psf-g-TPGS (M-III, PTC) were compared against those of unmodified Psf membrane (M-I, Psf) and unmodified Psf-TPGS blend membrane (M-II, PTB). The in vitro cellular compatibility was tested in hepatocarcinoma cell line (HepG2); the cells grown on membrane surface were examined by SEM. Results confirmed that the modified membrane is hydrophilic, is non-toxic, and may have improved efficiency in hemodialysis. Hemocompatibility of M-III, PTC had a slightly better performance over M-I; M-I showed better performance in the cellular attachment, which shows the promising role of the grafted hydrophilic polymer for related biocompatibility applications.

Water-Soluble 8-Hydroxyquinoline Conjugate of Amino-Glucose As Receptor for La3+ in HEPES Buffer, on Whatman Cellulose Paper and in Living Cells

A water-soluble glucopyranosyl conjugate, L, has been synthesized and characterized by different analytical and spectral techniques. The L has been demonstrated to have switch-on fluorescence enhancement of ∼75 fold in the presence of La(3+) among the nine lanthanide ions studied in the HEPES buffer at pH 7.4. A minimum detection limit of 140 nM (16 ± 2 ppb) was shown by L for La(3+) in the buffer at physiological pH. The utility of L has been demonstrated by showing its sensitivity toward La(3+) on Whatman filter paper strips. The reversible and reusable action of L has been demonstrated by monitoring the fluorescence changes as a function of the addition of La(3+) followed by F(-) and HPO4(2-) ions. The complexation of L by La(3+) was shown by absorption spectra wherein isosbestic behavior was observed. The Jobs plot suggests a 2:1 complex between L and La(3+), and the same was supported by ESI-MS. The control molecular study revealed the necessity of hydroxy quinoline and the amine group for La(3+) ion binding and the glyco-moiety to bring water solubility and biocompatibility. The structural features of the [2L+La(3+)] complex were established by DFT computational calculations. The chemo-ensemble, [2L+La(3+)], is shown responsible for providing intracellular fluorescence imaging in HepG2 cells.

Functionally coated polyethersulfone hollow fiber membranes: A substrate for enhanced HepG2/C3A functions

Hollow fiber membrane (HFM) based liver assist systems are a life-saving bridge for patients until a donor organ is available for transplantation or until liver regeneration. However, liver cell attachment and functional maintenance on HFM surface is a major challenge in bio-artificial liver (BAL) support systems. In the present study, novel glutaraldehyde (GTA)-crosslinked gelatin (gel)-coated polyethersulfone (X-gel-PT) HFMs were manufactured using triple orifice spinneret by the dry-wet spinning method. HFMs were characterized for morphology, outer surface roughness, hydrophilicity, tensile strength, thermal stability, BET surface area and pore volume measurements, permeability and rejection. Fourier transform infrared spectroscopy, and transmission electron microscopy confirmed the GTA-crosslinked gel-coating in the X-gel-PT HFMs, which provided the desirable extracellular matrix-like environment to the HepG2/C3A cells. The results of in-vitro hemocompatibility tests showed the better suitability of the developed HFMs for the blood-contact application. X-gel-PT HFMs showed significantly better cellular attachment and proliferation of HepG2/C3A cells on day 3 and 6, as shown by scanning electron and confocal microscopy. Significantly high urea synthesis and albumin secretion seen indicated the improved functional and metabolic activity of HepG2/C3A cells. Thus, the developed X-gel-PT HFMs is a suitable substrate for the hepatocyte culture, mass culture, and development of BAL support system.

Islet encapsulated implantable composite hollow fiber membrane based device: A bioartificial pancreas

Islets from xeno-sources and islet like clusters derived from autologus stem cells have emerged as alternatives to cadaveric pancreas used for treatment of type 1 diabetes. However, the immuno-isolation of these islets from the host immune system suffers from the issue of biocompatibility and hypoxia. To overcome the issues of immunobarrier biocompatibility, we developed a Polysulfone (Psf)/TPGS composite hollow fiber membrane (HFM) using a hollow fiber spinning pilot plant specially developed for this purpose. Important structural variables such as fiber material, dope composition, dimensions, surface characteristics etc., were precisely engineered and tuned for bioartificial pancreas application. The HFMs were characterized for their morphology, molecular diffusion, selectivity and protein absorption. The optimized Polysulfone(Psf)/TPGS composite HFMs, which contained TPGS, exhibited uniformed structure with low insulin adsorption and high permeability of insulin. The HFM was further studied for the encapsulation and in-vitro growth with porcine and differentiated islets isolated from human umbilical cord Whartons jelly. To prove their efficacy under in-vivo conditions, the Polysulfone(Psf)/TPGS composite HFMs were encapsulated with either of these isolated cells (porcine islets or islet like cell clusters derived from mesenchymal stem cells isolated from human umbilical cord Whartons jelly) and they were transplanted in experimental STZ induced diabetic mice. The results showed restoration of normoglycemia for 30days, indicating their ability to respond efficiently to high glucose without immune-rejection. Thus, these results indicate that Polysulfone (Psf)/TPGS composite HFMs can be used as an implantable, immune-competent bioartificial pancreas as a therapy for type 1 diabetes.