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We synthesized POBA dye and studied its performance as a sensitizer and co-sensitizer. In addition, we present a simple method for producing Ni-doped TiO2 with various molar concentrations for use as a photoanode in a DSSC. Further, poly(vinylidene fluoride)/polyethylene glycol (PVDF-PEG) gel polymer electrolytes (GPEs) having different concentrations of 1-n-hexyl-3-methylimidazolium iodide were prepared and optimized for usage in DSSCs. We initially tested the performance of POBA dye on TiO2 and Ni-doped TiO2 photoanode materials. Among the POBA sensitized devices, 4% Ni–TiO2 showed a high efficiency of 1.85%. Then, we sensitized Z907 dye on the 4% Ni–TiO2 photoanode, followed by sensitizing it with POBA, which compensated the absorption defect of the Z907 dye as well as filling the gap between the standard dye molecules. This approach enhances and broadens the absorption spectrum of the dyes by molecular filling, compensates for the lack of absorption of Z907, and reduces the recombination of charges. The Z907-based DSSC showed 4.52% efficiency, and after co-sensitization, the DSSC showed an increase in efficiency (5.77%). These findings show that co-sensitizers can cover the naked spectrum in the ultraviolet-visible region, fill the empty space on Ni–TiO2, and reduce recombination reactions. The main motive of this research is to enhance the photo-ability of sensitizers and metal-free co-sensitizers in a Ni–TiO2 photoanode and blend gel polymer electrolyte-based DSSCs. [ABSTRACT FROM AUTHOR]

Highly sensitive hypoxia (H2O2)-activated photoresponsive polymeric nanoparticles for cocktail delivery of anticancer drugs doxorubicin (Dox) and chlorambucil (Cbl) were developed. The photoresponsive polymer conjugate was constructed by ring-opening polymerization (ROP) of caprolactone (as the tail) with 7-hydroxycoumarin chlorambucil (as the head). During nanoprecipitation, the polycaprolactone chain wrapped around the hydrophobic core (coumarin chlorambucil) to form a “shell”. Interestingly, the polycaprolactone-tagged coumarin-chlorambucil (PCL-CC) NPs provided sufficient space for co-encapsulation of another hydrophobic anticancer drug Dox with a loading efficiency of 13 wt%. The controlled release of Dox and Cbl from Dox–PCL-CC NPs was investigated under three different conditions: (i) in the presence of H2O2 (tumor microenvironment), (ii) photoirradiation using UV light of ≥365 nm for 60 min, and (iii) photoirradiation using UV light of ≥365 nm for 15 min in the presence of H2O2. Results showed that photoirradiation in the presence of H2O2 results in generation of reactive oxygen species (HOO–, OH–), which assist hydrolysis of the ester group in the polymeric backbone of Dox–PCL-CC NPs and UV irradiation leads to cleavage of the coumarin-chlorambucil ester linkage, leading to burst release of Dox and Cbl. The drug release profile from the NPs under three different conditions was monitored by different instrumental techniques, e.g. emission spectroscopy, MALDI-Tof mass spectrometry, DLS and HPLC analysis. In vitro biological studies revealed that the present system can efficiently deliver the cocktail anticancer drugs with full control over release into the tumor cells by means of H2O2 and light activation. [ABSTRACT FROM AUTHOR]