Radiation processing of bacterial cellulose-monolaurin wound dressing: Physicochemical effects, functional analysis, and sterilization.

A commercial bacterial cellulose-monolaurin wound dressing was investigated for changes in the chemical structure, mechanical strength, thermal degradation, morphology, and functional swelling properties after exposure to gamma and electron beam radiations at doses 15-50 kGy. Radiation-induced oxidation occurred as seen in the FT-IR peaks at 1720-1750 cm-1. Degradation of the cellulosic network was observed in tensile strength reduction and shift in degradation temperature to lower values. The SEM cross-section images of the irradiated dressings revealed a less dense nanostructure network compared to the non-irradiated samples while the XRD diffractograms indicated a change in lattice direction/plane. Despite these changes, irradiation caused no significant effect on the functional properties especially at 15-25 kGy doses where most biomedical devices are sterilized. All irradiated wound dressings exhibited physical integrity, increased exudate absorption, and water vapor transmission rate - properties beneficial to wound-healing functionality. The pre-selected sterilization dose of 15 kGy for each ionizing radiation was successfully verified and substantiated following ISO 11137-2:2016, hence ionizing radiation is a suitable sterilization modality for the product.

Hemostatic efficacy evaluation of radiation-crosslinked carboxymethyl cellulose granules and kappa-carrageenan/polyethylene oxide/polyethylene glycol dressing in rat bleeding models.

Carboxymethyl cellulose granules (CMC-G) and kappa-carrageenan/polyethylene oxide/polyethylene glycol dressing (KPP-D) hemostatic agents, developed through radiation-induced crosslinking and sterilization, were tested in Sprague-Dawley rats using three bleeding models: (a) deep wound with the puncture of femoral artery; (b) aortic puncture; and (c) partial nephrectomy. Dressing and granules were applied in the animals without sustained compression and monitored for a period of 7 or 14 days. Comparisons were made against the commercial chitosan-based agent, Celox (CLX). Primary outcomes observed were bleeding time, the incidence of re-bleeding, animal survival, as well as gross and microscopic changes. The KPP-D group showed the shortest bleeding time for all bleeding models (a. 2.75 ± 0.64, b. 1.63 ± 0.54, c. 2.05 ± 0.62), significantly faster than all the other treatment groups. KPP-D also registered the highest survival rate of 100% with no display of gross abnormalities. CMC-G showed comparable bleeding time with CLX products but had a better survival rate at 98% compared to 96%. The incidence of re-bleeding was greater in CLX treated groups as well as more occurrence of granular adhesions that impacted mortality outcomes. Findings indicate the efficacy of KPP-D in the treatment of severe hemorrhage due to traumatic injury and intraoperative cases, while CMC-G was more suited for external trauma. Complications arising from inflammation, granules deposition, and adhesions emphasize stringent handling and removal of granular hemostat as a critical consideration in hemostat development and testing.

Antioxidant activity potential of gamma irradiated carrageenan.

The antioxidant capacity of irradiated κ-, ι-, λ-carrageenans were investigated using the hydroxyl radical scavenging assay, reducing power assay and DPPH radical scavenging capacity assay. The degree of oxidative inhibition increased with increasing concentration and dose. The type of carrageenan had also an influence on its antioxidant activity which followed the order of lambda

Comparative studies on the conformational change and aggregation behavior of irradiated carrageenans and agar by dynamic light scattering.

The conformational associative properties of kappa-, iota-, and lambda-carrageenan and agar with irradiation dose were studied by dynamic light scattering. The random scission of the carrageenans and agar by gamma irradiation resulted in the formation of polydispersed lower molecular weight fragments. At high doses, the system moves towards uniformity. Conformational change from coil to helix was observed in all carrageenans and agar at doses up to 100 kGy. The conformational change in lambda-carrageenan may be due to the irregular and hybrid structure of this polysaccharide. Only agar and lambda-carrageenan still undergo conformational transition at a high dose of 200 kGy. Gelation is observed for kappa-, iota-carrageenan up to a dose of 50 kGy while gelation is still observed at 100 kGy for agar. Increase in the hydrodynamic radius with decreasing temperatures for the non-irradiated carrageenans follows this order: lambda-carrageenan>kappa-carrageenan>iota-carrageenan. Slight increases in hydrodynamic radius were observed with irradiation.