Preparation Of Phenylboronic Acid Grafted Chitosan For Insulin Loading And Release In Vitro

Diabetes is a common disease characterized by basal metabolic disorders and hyperglycemia.It is another major disease that affects human health and life after tumors,cardiovascular and cerebrovascular diseases.Insulin is currently the indispensable drug for the treatment of diabetes,but long-term insulin injection can cause allergic reactions,insulin neuritis,obesity,insulin resistance,subcutaneous fat atrophy and other adverse reactions.To improve the safety of insulin administration,designing a glucose-responsive carrier can improve insulin drug compliance and relieve patient pain.Phenylboronic acid is a type of Lewis acid that can combine with 1,2 or 1,3hydroxyl groups to form a stable borate structure.Utilizing this property,the phenylboronic acid-introduced high molecular material can bear glucose responsiveness and insulin-regulating release.In this study,phenylboronic acid was used as the glucose-responsive group and grafted on the structure of natural polymers such as chitosan to achieve glucose-responsiveness and sustained release of insulin.3-carboxy-4-fluorophenylboronic acid(FPBA)was activated with EDC and NHS as activators and grafted onto chitosan(CS)with different molecular weights to form chitosan-phenylboronic acid polymer(CS-FPBA).The effects of solvent type,pH value,molar ratio of raw materials,activation time and reaction time on the grafting reaction were systematically studied.The insulin loading and release behavior of the grafted CS in vitro were studied,and the relationship between insulin release and glucose concentration was determined.Results show that the reaction conditions to obtain the maximum grafting rate is: DMSO / PBS solvent system,molar ratio CS: FPBA: EDC:NHS = 1: 2: 2: 2,activation time 4h,reaction time 24 h,optimum reaction pH: 5(for2.2kDa CS),8(for 50.0 kDa CS),12(for 400.0 kDaCS).The encapsulation rate of the product to insulin was 46 to 56% and the drug loading was 23 to 27% by weight.Thematerial is glucose-responsive,intelligently controlled release and insulin sustained-release.The insulin can be completely released in a simulated hyperglycemic environment.In addition,cytotoxicity experiments showed that the material is mostly non-toxic to 3T3 cells and has potential for in vivo applications.