No abstract

A single ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) that causes inflammation of the colonic mucosa at the distal colon and rectum. The mainstay therapy involves anti-inflammatory immunosuppression based on the disease location and severity. The disadvantages of using systemic corticosteroids for UC treatment is the amplified risk of malignancies and infections. Therefore, topical treatments are safer as they have fewer systemic side effects due to less systemic exposure. In this context, pH sensitive and enzymatically triggered hydrogel of pectin (PC) and polyacrylamide (PAM) has been developed to facilitate colon-targeted delivery of budesonide (BUD) for the treatment of UC. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), swelling ratio, and drug release. FT-IR spectroscopy confirmed the grafting as well loading of BUD in hydrogel. XRD showed the amorphous nature of hydrogel and increment in crystallinity after drug loading. On the other hand, SEM showed that the hydrogels exhibited a highly porous morphology, which is suitable for drug loading and also demonstrated a pH-responsive swelling behaviour, with decreased swelling in acidic media. The in-vitro release of BUD from the hydrogel exhibited a sustained release behaviour with non-ficken diffusion mechanism. The model that fitted best for BUD released was the Higuchi kinetic model. It was concluded that enzyme/pH dual-sensitive hydrogels are an effective colon-targeted delivery system for UC.

Conformation of biomolecules like DNA, peptides and amino acids play vital role during nanoparticle growth. Herein, we have experimentally explored the effect of different noncovalent interaction between a 5′‐amine modified DNA sequence (NH2−C6H12‐5′‐ACATCAGT‐3′, PMR) and arginine during the seed‐mediated growth reaction of gold nanorods (GNRs). Amino acid‐mediated growth reaction of GNRs results in a snowflake‐like gold nanoarchitecture. However, in case of Arg, prior incubation of GNRs with PMR selectively produces sea urchin‐like gold suprastructures, via strong hydrogen bonding and cation‐π interaction between PMR and Arg. This distinctive structure formation strategy has been extended to study the structural modulation caused by two structurally close α‐helical RRR (Ac‐(AAAAR)3A−NH2) peptide and the lysine mutated KKR (Ac−AAAAKAAAAKAAAARA−NH2) peptide with partial helix at the amino terminus. Simulation studies confirm that a greater number of hydrogen bonding and cation‐π interaction between the Arg residues and PMR resulted in the gold sea urchin structure for RRR peptide against KKR peptide.