Fabrication of thymol-loaded bacterial cellulose membranes impregnated with silver nanoparticles for improved antibacterial activity

Date

4-2014

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Evelyn B. Rodriguez

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

This study was conducted to prepare thymol-loaded bacterial cellulose (BC) membranes impregnated with silver nanoparticles (AgNPs) for antimicrobial applications, specifically for wound healing applications. Preparation of BC using the traditional method of producing nata de coco afforded gelatinous sheets of BC characterized by a 3-dimensional network of interwoven fibers, as shown by SEM and AFM analyses. The mean diameter of the fibers was found to be 68.6 nm ± 8.76 nm. Hydrothermal synthesis of AgNPs in the BC matrix resulted in the formation of small-sized nanoparticles with mean size of 12.6 nm ± 3.9 nm. The silver content of the bacterial cellulose-silver nanoparticle (BC-AgNP) membranes was determined spectrophotometrically using a complexation technique followed by a reduction step. The silver content was found to be 0.162 % ± 0.056 %. Thymol was loaded to the BC-AgNP composite by swelling method to improve its antibacterial activity. The presence of thymol was confirmed by UV and SEM analyses. Thymol content was found to be 0.027 mg thymol/ cm2 of the membrane. SEM images also showed the presence of thymol particles with sizes ranging from 0.90 μm to 2.20 μm. Release studies of silver and thymol from BC membranes revealed that both exhibited a steady release behavior over time, which was attributed to the unique fibrillar nature of BC. At day 7, 57 % silver was released from the BC-AgNP membrane and 64 % from BC-AgNP-thymol membrane. For thymol, 79 % of the thymol was already released by the 16th hour. Swelling studies of the BC and BC-AgNP membranes revealed that after 6 hours, the dried BC and BC-AgNP absorbed water 6 and 5 times their weight, respectively, an indication of good swelling ability. Antimicrobial studies of BC-AgNP and BC-AgNP-thymol was evaluated using disk diffusion and two compartment methods against Pseudomonas aeruginosa and Staphylococcus aureus. Disk diffusion tests revealed that BC membranes impregnated with AgNPs exhibited inhibition zones. Results from two compartment method showed that both BC-AgNP and BC-AgNP-thymol reduced the colony counts in the plate by more than 90%. It was also observed that BC-AgNP-thymol exhibited a higher antimicrobial activity than BC-AgNP especially against the Gram-negative P. aeruginosa. In vivo angiogenesis assay using duck embryo CAM revealed that BC-AgNP-thymol membranes exhibited increase in mean size, mean length and mean total number of junctions of the blood vessels of the duck embryo. These results indicate that BC-AgNP-thymol membrane possesses angiogenic potential, which may be beneficial for wound healing applications.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 C42 /L44

Document Type

Thesis

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