Photodynamic inactivation of microorganisms

The problem of microorganism inactivation is important for both clinical treatment and environmental protection. 

New antimicrobial approaches that are effective, affordable, and widely applicable are urgently needed. The photodynamic method has been suggested as a possible new strategy for microorganism inactivation [1,2]. 

Bioinorganic Photochemistry Grazyna Stochel, Malgorzata Brindell, Wojciech Macyk, Zofia Stasicka, Konrad Szacilowski 2009 Grazyna Stochel, Malgorzata Brindell, Wojciech Macyk, Zofia Stasicka, Konrad Szacilowski. ISBN 978-1 -405-16172-5 

Photodynamic ACT (PACT), similar to photodynamic therapy (PDT) described in Chapter 17, utilizes photosensitizers and visible or UV light in order to induce a phototoxic response, usually via oxidative damage. For some time the disinfection of blood products, particularly for viral inactivation, has been the major use of PACT, although more and more clinically based protocols are being developed, eg in the treatment of oral infections. The technique has been shown to be effective in vitro against bacteria (including drug resistance strains), yeasts, viruses, and parasites. 

The ability of a light-drug combination to kill microorganisms is not a new idea and has been known for over 100 years [3]. In fact the concept of PDT was initiated in 1900 when Raab described the antimicrobial action of acridine and light on Paramecium species [4], Flowever, only recently has the search for alternative treatments for antibiotic-resistant pathogens stimulated the PACT development. 

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Several papers have been published on the photodynamic inactivation of microorganisms in waste water treatment (Acher and Juven, 1977 Gerba et al., 1977a,b, Kussovski et al., 2001 Martin and Perez-Cruet, 1987). Despite the fact that the effectiveness of photodynamic disinfection... 

TABLE 3.8 Photodynamic inactivation of microorganisms on the surface of paper treated with conjugates of Rose Bengal (RB) and Phloxine B (PhB) with poly (vinyl amine) (PVAm) (adapted from Brovko et ai, 2009)... 

The cytotoxic and photodynamic inactivation of microorganisms by Rose Bengal is an important line of research [337]. Rose Bengal causes ATP depletion [338] in killing Escherichia coli B/r [339]. Since E. coli is also killed... 

Fundamentals of heterogeneous photocatalysis have been described in Chapter 7. The photodynamic activity of Ti02 (based on its photocatalytic activity and high efficiency in ROS generation) can find applications in photodynamic therapy (PDT) and photodynamic inactivation of microorganisms (PDI), described in Chapters 17 and 18, respectively. Selected environmental aspects of heterogeneous photocatalysis are described below. 

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