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/cm 2 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.

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The embedment of barium titanate nanoparticles (BaTiO3 NPs) in the polyaniline (PANI) matrix play a significant role in enhancing the properties of nanocomposites. In this research work BaTiO3@PANI polymer nanocomposites were well synthesized by the in-situ polymerization by embedding different concentrations of BaTiO3 NPs (1wt%, 3wt%, 5wt%, 7wt %) in the polyaniline matrix. The resulting nanocomposites were characterized for their structural, optical and photocatalytic properties. BaTiO3@PANI nanocomposites exhibited higher photocatalytic activity than pure PANI and pure BaTiO3 NPs towards the organic and toxic pollutants in liquid phase under visible light irradiation. The embedment of BaTiO3 NPs in PANI have played an important role in affecting the photo reactivity and the increased weight ratio of BaTiO3 NPs in PANI increased the photocatalytic efficiency of nanocomposites. The structural and optical properties were studied by XRD, FTIR and UV-Visible spectroscopy. The XRD confirmed the embedment of BaTiO3 NPs in PANI matrix. The Fourier Transform Infra-Red (FTIR) spectroscopy identified the various functional groups and their respective vibrational and stretching modes. The results revealed that higher concentration of BaTiO3 NPs in PANI proves to be a better photocatalyst. This work provides a comprehensive information to modify the polymers with nanoparticles.

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