奈米技術在光動力殺菌之應用   全文下載

Nanotechnology in Antimicrobial Photodynamic Inactivation

光動力治療與光動力失活的技術是利用可見光與光感物質來抑制細胞的活性。光動力治療目前已應用於許多類型的癌症治療。雖然利用光感物質及光源已成功於癌症的治療，然而抗菌光動力失活（光動力殺菌）則因其具有高成效及減少抗藥性產生的可能性，已發展成對抗細菌感染的新興治療方式。抗藥性的產生是因為微生物部分有機體形成生物膜，提供了微環境來保護微生物免於受抗生素及宿主細胞的免疫攻擊。體外實驗顯示，光動力失活對於對抗革蘭氏陽性菌及革蘭氏陰性菌均有效，但於體內實驗中則發現，有許多因素都會影響光動力失活的效益，例如藥物與血漿蛋白的結合等。為了克服這些因素的影響，可利用不同奈米技術來增加光動力失活的效益，如利用微脂體、微胞、奈米粒子等載體，以減少血漿蛋白與光感物質的結合。研究顯示利用合適之奈米載體包覆光感物質的確能夠增加光動力失活（光動力殺菌）效益。

Photodynamic therapy (PDT) and photodynamic inactivation (PDI) are technologies that utilize visible light and photosensitizers (PS) to inactivate cells. PDT is currently in use for the treatment of several types of tumors. Although cancer has been successfully treated with PS and light, antimicrobial PDI is emerging as a new treatment modality for bacterial infections due to its effectiveness and less likelihood of inducing bacterial resistance. Resistance to therapy is in part due to the ability of the organisms to form a biofilm, which provides a microenvironment that protects the microorganism from antibiotics and attack by the host’s immune system. In vitro, PDI nonetheless was shown to be effective against Gram-negative and Gram-positive bacteria. When used in-vivo however, several factors were shown to influence and diminish the effectiveness of PDI, such as aggregation of PS and plasma protein binding. To circumvent these factors, different nanotechnology platforms were used to enhance the photodynamic inactivation efficacy, such as liposomes, micelles and nanoparticles, by reducing the PS aggregation and albumin binding to the PS. In general, studies have shown that photody-namic inactivation efficacy could be enhanced when suitable nanocarriers are used to deliver the PS.