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Shakir Khan,1 Fahad Alam,2 Ameer Azam,2 Asad U Khan11Interdisciplinary Biotechnology Unit, 2Center of Excellence in Material Science (Nanomaterials), Aligarh Muslim University, Aligarh, IndiaAbstract: This article explores the novel gold nanoparticle–enhanced photodynamic therapy of methylene blue against recalcitrant pathogenic Candida albicans biofilm. Physiochemical (X-ray diffraction, ultraviolet-visible absorption, photon cross-correlation, FTIR, and fluorescence spectroscopy) and electron microscopy techniques were used to characterize gold nanoparticles as well as gold nanoparticle–methylene blue conjugate. A 38.2-J/cm2 energy density of 660-nm diode laser was applied for activation of gold nanoparticle–methylene blue conjugate and methylene blue against C. albicans biofilm and cells. Antibiofilm assays, confocal laser scanning, and electron microscopy were used to investigate the effects of the conjugate. Physical characteristics of the gold nanoparticles (21 ± 2.5 nm and 0.2 mg/mL) and methylene blue (20 µg/mL) conjugation were confirmed by physicochemical and electron microscopy techniques. Antibiofilm assays and microscopic studies showed significant reduction of biofilm and adverse effect against Candida cells in the presence of conjugate. Fluorescence spectroscopic study confirmed type I photo toxicity against biofilm. Gold nanoparticle conjugate–mediated photodynamic therapy may be used against nosocomially acquired refractory Candida albicans biofilm.Keywords: Candida biofilm, gold nanoparticle–methylene blue conjugate, photodynamic therapy

Asad U KhanMedical Microbiology and Molecular Biology Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, IndiaThis is with reference to an article published recently in your journal regarding the antibiotic activity of chitosan-coated silver nanoparticles.1 This is an inspiring move towards control of infection caused by multidrug-resistant bacteria which has become a serious problem for clinicians and physicians worldwide.2 At the moment, carbapenems are being used as the drugs of choice to combat infections. However, the emergence of carbapenem resistance has changed current remedial approaches in the management of serious infections. One of the latest enzymes, NDM-1 (New Delhi metallo-β-lactamase-1), first identified in a Swedish patient of Indian origin in 2008,3 has been key in the development of resistance to almost all antibiotics. Infection caused by NDM-1 producers is widespread on the Indian subcontinent,4 and is now emerging in the US and other countries throughout the world.5View original paper by Jena and colleagues.

Asad U KhanMedical Microbiology and Molecular Biology Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, IndiaConcerning the recent article published in your journal on antibiofilm surface functionalization of catheters.1 This is an admirable approach to inhibit biofilm formation on the surfaces of various implants. Currently, a number of biomedical devices and implants are commonly used in hospitals and clinics. Over the past few decades, a number of knee and hip implants have been introduced to save lives and restore quality of life. Moreover, a significant increase in the use of stents, heart valves, vascular grafts, catheters, and other implantable devices are being introduced worldwide. However, regrettably, these surfaces are prone to microbial infections and hence device-related infections have become a major source of infection which may ultimately lead to a high mortality rate in the hospital setting.2View original paper by Lellouche and colleagues.