Simulation of the bioadhesive gelatin-alginate conjugate loaded with antibiotic drugs

In the present research, molecular modeling methods were used to study a novel bioadhesive composed of gelatin (protein) and alginate (polysaccharides), crosslinked with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Three antibiotic drugs were added to the bioadhesive: Vancomycin, Ofloxacin, and Clindamycin. Computational tools were applied to estimate the crosslinking degree and compare the effect of the antibiotics on the physical properties of the gelatin-alginate conjugate. The crosslinking degree was estimated by calculating the enthalpy of mixing of gelatin with alginate and their interaction with the crosslinking agents. The calculations revealed that gelatin mixes well with alginate, which enables their crosslinking. Various ratios between EDC and NHS were examined, and an optimal ratio was found. The interaction of alginate-gelatin conjugate with the antibiotics was correlated to the experimental results of bonding strength. The most significant interaction of the conjugate is with clindamycin. The gelatin part is responsible for the strong interaction with clindamycin, and alginate forms strong interaction with ofloxacin. Thus, the interaction of alginate-gelatin conjugate with the antibiotics is governed by the proportion between gelatin and alginate in the conjugate. The degradation rate of gelatin-alginate was related to its interaction with water. It was found that the conjugate is highly hydrophilic. Gelatin is more soluble in water than both alginate and alginate-gelatin and is probably the part in the conjugate that governs the solubility and degradation rate. Therefore, the degradation rate of the conjugate can be controlled by changing the proportion between gelatin and alginate.