Starch-Based Nanoparticles, Hydrogels and Films for Biomedical and Industrial Applications

Ain Nadirah, Romainor (2018) Starch-Based Nanoparticles, Hydrogels and Films for Biomedical and Industrial Applications. PhD thesis, Universiti Malaysia Sarawak(UNIMAS).

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Abstract

Environmental concerns about the increasing use of non-biodegradable material and the associated waste are raising the demand for biodegradable resources such as starch to replace petroleum-based products, especially in biomedical and plastic film industrial application. In this study, starch-citrate was synthesized by reacting native sago starch (Metroxylon sagu) with citric acid in an esterification reaction. Starch-citrate was prepared in the forms of nanoparticles, hydrogel and films, and their potential biomedical and industrial applications were explored. The presence of citric acid on starch-citrate molecules was observed to confer pH-responsiveness to the latter. In a simulated stomach (pH 1.2), starch-citrate nanoparticles were observed to release 100% of paracetamol (the model drug) in a slow and sustained manner over 32 hours. However, in simulated blood and intestines (pH 7.4 and 8.6 respectively), the drug release rates were faster, whereby 100% of paracetamol was released within 16 and 12 hours respectively. Therefore, the premature release of drug molecules in the stomach could be prevented by using starch-citrate nanoparticles as controlled-release carriers. In addition, starch-citrate nanoparticles showed no cytotoxicity effect at concentration of 0.5-6 mg. mL-1, revealed that the formulated nanoparticles was free from harmful material and safe to be used in biomedical field. The role of starch-citrate hydrogels as an antibacterial hydrogel drug carrier was explored. It was observed that sustained release of penicillin G from starch-citrate hydrogel was achieved in 120 hours. In addition, antibacteribial tests confirmed the effectiveness of the hydrogels against Gram-positive and Gram-negative bacteria strains – including multiply antibiotic-resistant (MAR) ones – as almost 99% of the bacterial cells were suppressed. Apart from that, the optimized composition of starch-citrate films also killed 99% of pathogenic food-related bacteria of Salmonella thypimurium (S. thypimurium), iv Listeria monocytogenes (L. monocytogenes) and Escherichia coli (E. coli). Mould growth from spoilt cake and bread were cultured and the fungal were isolated and identified. It was observed that starch-citrate films able to suppress almost 87-99% of Aspergillus spp. and Rhizopus spp. contaminated on cake and food products. As a result, food which is wrapped in starch-citrate films exhibited longer shelf lives (over 10 and 40 days for cake and bread respectively) compared to those wrapped in commercial food films. In conclusion, biodegradable starch-citrate material has a huge potential to be used in biomedical and food packaging film application, as shown in the promosing result of the drug release (which prevent the premature release of drug) and antimicrobial effect, thereby increasing the application value of hydrogel and packaging film formulation, respectively.

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