Research Papers - School of Natural Sciences

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    PublicationOpen Access
    Chitosan-Starch Biocomposite for Enhanced Curcumin Delivery: Kinetic Modeling of pH and Ionic Strength Responsive Release and Evaluation of Biological Efficacy
    (American Chemical Society, 2026-07-21) Abeywickrama, L; Wijayawardana, S; Thambiliyagodage, C; Jayanetti, Madara
    A drug delivery system composed of chitosan and starch was used to deliver curcumin effectively by enhancing its pharmacokinetic properties. The sustained release of the synthesized delivery system was evaluated using a kinetic modeling approach along with its biological efficacy. The SEM analysis confirmed the coupling of starch and chitosan and loading of curcumin into the matrix during synthesis. Crystallographic orientation of the delivery system was confirmed by XRD, and the FT-IR data confirmed the successful loading of curcumin. TG analysis indicated that the increment in decomposition temperature of the composite is due to the incorporation of curcumin into the composite. BET analysis revealed the reduction in the BET surface area and pore volume in the synthesized composite, confirming successful loading. The IC50 values of the curcumin and composite for the DPPH assay were 17.81 μg/mL and 38.77 μg/mL, respectively. Composite material has shown enhanced antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa at 20 mg/mL, with inhibition zones of 15.56 ± 0.29 and 10.11 ± 0.44 mm, respectively. Allium cepa cytotoxicity assay confirmed that all the synthesized materials promote mitosis at 2.5 mg/mL concentration. The pH and ionic strength responsive release of curcumin was studied by fitting the release data into six kinetic models, including Korsemeyer–Peppas (KP) and Peppas–Sahlin (PS), which has not been reported earlier for the synthesized system. The KP and PS models were selected to interpret the release mechanism based on R2. A combination of Fickian diffusion, relaxation and swelling dominates the curcumin release. According to the KP model, quasi-Fickian diffusion is responsible for the release in acidic and alkaline pH, whereas non-Fickian diffusion occurs at pH 6.7. At higher [NaCl], relaxation is responsible for the release (n > 0.43, kD = 0), while a combination of diffusion and relaxation governs the release at lower [NaCl]. These behaviors are related to the chemical composition of chitosan and the release media, where the electrostatic repulsion, protonation and charge screening contribute to curcumin release.
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    PublicationOpen Access
    An evaluation of genetic diversity in micropropagated anthurium using starch gel electrophoresis
    (Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1992) Peiris, S; Mantell, S. H; Peiris, C. N; Senanayake, Y. D. A
    Anthurium andreanum Lind is a cut flower which is in high demand in the local and export cut flower trades in Sri Lanka. For commercial production of export anthurium cut flowers, it is essential that the selected elite qualities of the flowers borne on this original mother stock plants are maintained consistantly through many generations on vegetative multiplication. Tliis paper reports on stanch gel electrophoresis which was adapted successfully on anthuriums to evaluate genetic diversity if any, in plants derived either from seedlings, conventional stem cuttings or micropropagated clonal plants. Buffered leaf extracts were compared by means of horizontal starch gel electrophoresis to check the variability in cv. 'Crinkled Red'. Isoenzyme banding patterns of malic dehydrogenase (MDH), 6 phosphogluconic dehydrogenase (6 PGDH), phosphogluco isomerase (PGI) and diaphorase (DIAP) were used. Extracts of 105 seedlings, 60 clonal plants produced through rhizome cuttings and 150 in vitro propagated plants were compared to detect possible somaclonal variations in the daughter plants produced. Results of starch gel electrophoresis showed that extracts of seedling plants contained variations, expressed as percentages showing deviant patterns in all five isoenzyme systems assessed: MDH 14%, 6 PGDH 13%, GOT 12%, PGI 14% and DIAP 16%. None of the clonal plants or in vitro propagated plants tested using this technique showed variations in any of the isoenzyme compared. Tlie results of this study showed the genetic diversity in anthwium seedling plants and confirmed that stability was maintained in vegetatively propagated and in vitro propagated plants. Since in vitro propagation produces a large number of uniform and genetically stable plants, in vitro multiplication would appear to be suitable for use in the Sri Lankan floriculture industry