Wet microcontact printing (µCP) for micro-reservoir drug delivery systems

When micro-reservoir-type drug delivery systems are fabricated, loading solid drugs in drug reservoirs at microscale is often a non-trivial task. This paper presents a simple and effective solution to load a small amount of drug solution at microscale using 'wet' microcontact printing (µCP). In this wet µCP, a liquid solution containing drug molecules (methylene blue and tetracycline HCl) dissolved in a carrier solvent was transferred to a target surface (drug reservoir) by contact printing process. In particular, we have investigated the dependence of the quantity and morphology of transferred drug molecules on the stamp size, concentration, printing times, solvent types and surfactant concentration. It was also found that the repetition of printing using a non-volatile solvent such as polyethylene glycol (PEG) as a drug carrier material actually increased the transferred amount of drug molecules in proportion to the printing times based on asymmetric liquid bridge formation. Utilizing this wet µCP, drug delivery devices containing different quantity of drugs in micro-reservoirs were fabricated and their performance as controlled drug delivery devices was demonstrated.