Synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinking on the properties of agar.

In this work, the modification of agar is presented with the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinked agar. The effect of crosslinking agar with succinic acid on tensile strength and water absorption were studied. Crosslinking was confirmed with Fourier infrared spectroscopy. The tensile strength of agar was increased by 70% by succinic acid crosslinking (from55 ± 9.97 MPa to 93.40 ± 9.97 MPa) and the crosslinked agar absorbed only 18.66% water compared to uncrosslinked agar. The tensile strength of agar was increased by 56% by bacterial cellulose reinforcement (55 ± 9.97 MPa to 86.30 ± 14.70 MPa). The strength of agar was improved by 101% by the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinking (55 ± 9.97 MPa to 111 ± 12.30 MPa). Cytocompatibility studies of the developed films suggested that the crosslinked samples can also have potential applications in biomedical engineering apart from packaging applications.

Crosslinking of agar by diisocyanates.

In the present study, crosslinking of agar using diisocyanate (DI) was demonstrated to limit the high water absorption property of agar. In addition, the efficacy of aromatic diisocyanate, DDI (4, 4 diphenyl diisocyanate) and aliphatic diisocyanate, HDI (1, 6 hexamethylene diisocyanate) on crosslinked agar properties was compared. The water uptake was successfully reduced by crosslinking and its minimum values observed for DDI and HDI crosslinked agar was 33.6% and 43.6%, respectively in comparison to agar (206%). The maximum tensile strength was observed for DDI crosslinked agar (45.3 MPa) which was higher than HDI crosslinked agar (30.6 MPa) and agar (31.7 MPa). The aromatic diisocyanates crosslinked agar showed better thermal resistance at higher temperature. It was observed that aromatic diisocyanate crosslinked agar more effectively than the aliphatic diisocyanate due to the higher reactivity. The crosslinked agar samples were hemocompatible and show non-toxic nature for cell proliferation.

Single step neutravidin patterning: a lithographic approach for patterning proteins.

Protein patterning on surfaces is studied extensively for its potential use in proteomic, nanostructures, drug delivery and sensing. Patterning of proteins at micro and nano scales is especially important not only to understand the function of patterned protein but also to study its interaction with subsequent layers of bio-molecules/cells. Micro scale protein patterning is especially difficult due to the fragile nature of proteins. The already available methods either involve complex chemistries or are specific to a few proteins. Thus, in this regard, a versatile approach to pattern proteins using neutravidin is developed. With this approach of lithography and subsequent lift-off of the photoresist, any biotinylated moiety can be patterned at micron scale resolution. Functionality of patterned neutravidin is confirmed by showing binding of biotinylated polystyrene beads and biotinylated antibodies. In addition, stronger physisorption of neutravidin on bare glass surface, as a result of acetone lift-off, helps sustain the protein layers onto the glass surface without the need of chemical immobilization.