Authors: G.K.M. Kalapala, P.K.-L. Fu
Affilation: Governors State University, United States
Pages: 356 - 359
Keywords: photodynamic therapy, drug delivery, antimicrobial, biofilm
Chronic wounds are considered as a pandemic health problem. Approximately 1% to 2% of the population in developing countries has experienced a chronic wound during their lifetime. In the United State States,the expense of treating chronic wounds constitutes over half of the total cost for all skin diseases, which exceeds $10 billion annually. For the last decade extensive basic science and clinical research in chronic wounds have suggested that pathogenic biofilm is the primary hindrance to the wound healing. Biofilms are highly organized, poly-species bacterial communities living within a protective extracellular matrix that they produce. They are difficult to detect and highly resistant to the host immune system or to antimicrobial elimination. Studies have shown that they can be up to 500 times more resistant to antibiotics than planktonic (unattached, freely living) cells. Owing to bacterial species within biofilms being exceptionally resistant to many traditional therapies, Photodynamic Antimicrobial Chemotherapy (PACT) can provide an effective alternative for chronic wound treatment. The principle of PACT is derived from traditional photodynamic therapy, which is a technique that uses the combination of light and nontoxic drugs (photosensitizers) to destroy specific targeted cells. After the inactive, nontoxic drug is applied topically or injected, it can only be activated by irradiation with a certain wavelength of light. The light switches on the drug, once the drugs are activated they can produce highly reactive intermediates such as reactive oxygen species (ROS) to destroy the targeted cells without damaging the surrounding healthy tissues. Once the irradiation is removed, the photosensitive drug will return to its stable, non-harmful state. It is very unlikely that bacteria will develop resistance to reactive oxygen species such as singlet oxygen and hydroxyl radicals. However, the main limitation of this technique would be the uptake kinetics of the photosensitizers in microorganisms. Therefore, in order to overcome this situation,the first criteria is to find a nanoencapsulated drug-carrying system that can easily penetrate the polymicrobial species habitat within biofilms. These encapsulated nanoparticles should be biodegradable, biocompatible, physically stable, and capable of delivering both hydrophilic and hydrophobic drugs. We have begun synthesis of 4 different categories of nanoparticles to explore their potentials.