The main goal of this project was to study and understand the release of gentamicin from in – situ, self – reactive drug delivery gelling matrix. The motivation behind this was to create a drug delivery mechanism for gentamicin and eliminate the need for re–injecting the drug multiple times into the patient. Gentamicin is used to treat various different bacterial infections of the central nervous system, blood, kidneys, gall bladder, bile duct, heart cavity linings, and heart valves. Pentaerythritol–tetrakis (3 – mercaptoproprionate; QT) was crosslinked with poly(ethylene glycol) diacrylate (PEGDA) having an average molecular weight of 575 with the help of Phosphate Buffer Saline (PBS), with a buffer ionic strength of 0.143M and a pH of 8.9 and 11, for the drug concentrations of 5 mg/mL and 50 mg/mL, respectively. The Michael – type reaction formed the crosslinked self – administering gelling matrix. With the gelling matrix starting to coagulate into a hydrophobic solid in about 5 minutes, the material was injected into Tygon tubing. After complete solidification, the drug – loaded gels were extracted from the tubing and divided into 1 cm cylinders. The cylinders with 5mg/mL and 50mg/mL drug concentration exhibited a sustained and controlled release curve for about 288 hours. This project as well as this drug delivery system can in the future be expanded for use in the delivery of more hydrophobic long – term drugs to the patient.