Background: Hydrogels are excellent drug carriers, but their inability to retain hydrophilic
drugs for a prolonged period of time has greatly limited their usage. Research has mostly focused on
intricate designs and manipulations of hydrogels to expand their applications in drug delivery.
Objective: In this study, a simple approach by incorporating a hydrophobic agent, octadecyltrichlorosilane
(OTS), to alginate hydrogel micro-granules (Alg-Ms), was investigated as an effective
technique to prolong the release of small hydrophilic drugs.
Methods: Sodium Benzoate (SB), a highly water-soluble antimicrobial and anti-inflammatory compound,
was used as a model drug. The presence of hydrophobic OTS impeded swelling of these OTS
incorporated Alg-Ms (OTS-Alg-Ms), hence sustaining the release of SB.
Result: The release data was fitted with Ritger-Peppas and Peppas-Sahlin models and the results showed
that SB released from OTS-Alg-Ms with higher OTS content was mainly controlled by Fickian diffusion;
with a lower OTS content, OTS-Alg-Ms swelled more easily, the combined diffusion and swelling
led to a faster SB release.
Conclusion: Thus, by simply tuning the OTS concentration in the solution where Alg-Ms were briefly
submerged in a predefined release period, from hours to a few days, small hydrophilic drugs from these
OTS-Alg-Ms could be successfully achieved.