Kinetics, Equilibrium, and Thermodynamics for Conjugation of Chitosan with Insulin-Mimetic [ meso-Tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-) in an Aqueous Solution

Chironjit Kumar Shaha; Bithy Sarker; Shurid Kishore Mahalanobish; Md Sharif Hossain; Subarna Karmaker; Tapan Kumar Saha

doi:10.1021/acsomega.3c05804

Kinetics, Equilibrium, and Thermodynamics for Conjugation of Chitosan with Insulin-Mimetic [ meso-Tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-) in an Aqueous Solution

ACS Omega. 2023 Oct 24;8(44):41612-41623. doi: 10.1021/acsomega.3c05804. eCollection 2023 Nov 7.

Authors

Chironjit Kumar Shaha^{1

2}, Bithy Sarker¹, Shurid Kishore Mahalanobish¹, Md Sharif Hossain³, Subarna Karmaker¹, Tapan Kumar Saha¹

Affiliations

¹ Department of Chemistry, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh.
² Veterinary Drug Residue Analysis Division, Institute of Food and Radiation Biology, Atomic Energy Research Establishment (AERE), Gonokbari, Savar, Dhaka 1349, Bangladesh.
³ Department of Biotechnology & Genetic Engineering, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh.

Abstract

This study investigated the conjugation of chitosan with the insulin-mimetic [meso-tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-), VO(tpps), in an aqueous medium as a function of conjugation time, VO(tpps) concentrations, and temperatures. To validate the synthesis of chitosan-VO(tpps) conjugate, UV-visible and Fourier transform infrared spectrophotometric techniques were utilized. Conjugate formation is ascribed to the electrostatic interaction between the NH₃⁺ units of chitosan and the SO₃^- units of VO(tpps). Chitosan enhances the stability of VO(tpps) in an aqueous medium (pH 2.5). VO(tpps) conjugation with chitosan was best explained by pseudo-second-order kinetic and Langmuir isotherm models based on kinetic and isotherm studies. The Langmuir equation determined that the maximal ability of VO(tpps) conjugated with each gram of chitosan was 39.22 μmol at a solution temperature of 45 °C. Activation energy and thermodynamic studies (E_a: 8.78 kJ/mol, ΔG: -24.52 to -27.55 kJ/mol, ΔS: 204.22 J/(mol K), and ΔH: 37.30 kJ/mol) reveal that conjugation is endothermic and physical in nature. The discharge of VO(tpps) from conjugate was analyzed in freshly prepared 0.1 mol/L phosphate buffer (pH 7.4) at 37 °C. The release of VO(tpps) from the conjugate is a two-phase process best explained by the Higuchi model, according to a kinetic analysis of the release data. Taking into consideration all experimental findings, it is proposed that chitosan can be used to formulate both solid and liquid insulin-mimetic chitosan-VO(tpps) conjugates.