Phytic Acid-Promoted Deposition of Gold Nanoparticles with Grafted Cationic Polymer Brushes for the Construction of Synergistic Contact-Killing and Photothermal Bactericidal Coatings.

Medical implants are constantly facing the risk of bacterial infections, especially infections caused by multidrug resistant bacteria. To mitigate this problem, gold nanoparticles with alkyl bromide moieties (Au NPs-Br) on the surfaces were prepared. Xenon light irradiation triggered the plasmon effect of Au NPs-Br to induce free radical graft polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA), leading to the formation of poly(DMAEMA) brush-grafted Au NPs (Au NPs-g-PDM). The Au NPs-g-PDM nanocomposites were conjugated with phytic acid (PA) via electrostatic interaction and van der Waals interaction. The as-formed aggregates were deposited on the titanium (Ti) substrates to form the PA/Au NPs-g-PDM (PAP) hybrid coatings through surface adherence of PA and the gravitational effect. Synergistic bactericidal effects of contact-killing caused by the cationic PDM brushes, and local heating generated by the Au NPs under near-infrared irradiation, conferred strong antibacterial effects on the PAP-deposited Ti (Ti-PAP) substrates. The synergistic bactericidal effects reduced the threshold temperature required for the photothermal sterilization, which in turn minimized the secondary damage to the implant site. The Ti-PAP substrates exhibited 97.34% and 99.97% antibacterial and antiadhesive efficacy, respectively, against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), compared to the control under in vitro antimicrobial assays. Furthermore, the as-constructed Ti-PAP surface exhibited a 99.42% reduction in the inoculated S. aureus under in vivo assays. In addition, the PAP coatings exhibited good biocompatibility in the hemolysis and cytotoxicity assays as well as in the subcutaneous implantation of rats.

Recent advances in engineered polymeric materials for efficient photodynamic inactivation of bacterial pathogens.

Nowadays, infectious diseases persist as a global crisis by causing significant destruction to public health and the economic stability of countries worldwide. Especially bacterial infections remain a most severe concern due to the prevalence and emergence of multi-drug resistance (MDR) and limitations with existing therapeutic options. Antibacterial photodynamic therapy (APDT) is a potential therapeutic modality that involves the systematic administration of photosensitizers (PSs), light, and molecular oxygen (O2) for coping with bacterial infections. Although the existing porphyrin and non-porphyrin PSs were effective in APDT, the poor solubility, limited efficacy against Gram-negative bacteria, and non-specific distribution hinder their clinical applications. Accordingly, to promote the efficiency of conventional PSs, various polymer-driven modification and functionalization strategies have been adopted to engineer multifunctional hybrid phototherapeutics. This review assesses recent advancements and state-of-the-art research in polymer-PSs hybrid materials developed for APDT applications. Further, the key research findings of the following aspects are considered in-depth with constructive discussions: i) PSs-integrated/functionalized polymeric composites through various molecular interactions; ii) PSs-deposited coatings on different substrates and devices to eliminate healthcare-associated infections; and iii) PSs-embedded films, scaffolds, and hydrogels for regenerative medicine applications.

Functional Attributes of Myco-Synthesized Silver Nanoparticles from Endophytic Fungi: A New Implication in Biomedical Applications.

To develop a benign nanomaterial from biogenic sources, we have attempted to formulate and fabricate silver nanoparticles synthesized from the culture filtrate of an endophytic fungus Penicillium oxalicum strain LA-1 (PoAgNPs). The synthesized PoAgNPs were exclusively characterized through UV-vis absorption spectroscopy, Fourier Transform Infra-Red spectroscopy (FT-IR), X-ray powder diffraction (XRD), and Transmission Electron Microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX). The synthesized nanoparticles showed strong absorbance around 430 nm with surface plasmon resonance (SPR) and exhibited a face-centered cubic crystalline nature in XRD analysis. Proteins presented in the culture filtrate acted as reducing, capping, and stabilization agents to form PoAgNPs. TEM analysis revealed the generation of polydispersed spherical PoAgNPs with an average size of 52.26 nm. The PoAgNPs showed excellent antibacterial activity against bacterial pathogens. The PoAgNPs induced a dose-dependent cytotoxic activity against human adenocarcinoma breast cancer cell lines (MDA-MB-231), and apoptotic morphological changes were observed by dual staining. Additionally, PoAgNPs demonstrated better larvicidal activity against the larvae of Culex quinquefasciatus. Moreover, the hemolytic test indicated that the as-synthesized PoAgNPs are a safe and biocompatible nanomaterial with versatile bio-applications.

Carica papaya (Papaya) latex: a new paradigm to combat against dengue and filariasis vectors Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae).

This study manifests the larvicidal efficacy of Carica papaya latex extract and silver nanoparticles (CPAgNPs) synthesized using latex, against developing immature juveniles of Aedes aegypti and Culex quinquefasciatus. Briefly, the latex was collected and fractioned with different solvents such as chloroform, methanol and aqueously. The obtained crude extracts were subjected to larvicidal activity in the dose-dependent method. After 24 h, the mortality rate was calculated and statistically analyzed. From the results, it was demonstrated that the chloroform extract displayed prominent activity in IInd and IIIrd instar larvae of A. aegypti and C. quinquefasciatus with better LC50 values followed by methanol and aqueous extract. Subsequently, we profiled the qualitative analysis of a chloroform extract through biochemical tests; Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. Moreover, we authenticated the major secondary metabolites and activated larvicidal compound present in the extract. Further, we synthesized CPAgNPs using aqueous latex extract and challenged with IInd and IIIrd instar larvae of A. aegypti and C. quinquefasciatus. Noticeably, the synthesized nanoproducts were showed 100% mortality in a 24-h treatment with significant LC50 values. Hence, this study has opened up new vistas in the field of parasitological research to develop Carica papaya latex as a new stratagem in the insect vector management program.

Isolation of limonoid compound (Hamisonine) from endophytic fungi Penicillium oxalicum LA-1 (KX622790) of Limonia acidissima L. for its larvicidal efficacy against LF vector, Culex quinquefasciatus (Diptera: Culicidae).

Upon screening for novel and potential biocompounds with larvicidal activities, we successfully isolated hamisonine (HMSN) a limonoid compound from endophytic fungi Penicillium oxalicum LA-1 of Limonia acidissima. The extracted compound structure was elucidated by spectral studies such as UV-vis spectroscopy, thin-layer chromatography, FTIR, LC-ESI-MS, 1H NMR, and 13C NMR upon comparing with the spectral data available in the literature. Further, the isolated HMSN was tested against III and IV instar Culex quinquefasciatus larvae. The outcome of this study clearly emphasize that the extracted compound HMSN possesses a stupendous larvicidal activity in a dose-dependent manner with the LC50 and LC90 values of 1.779 and 7.685 ppm against III instar larvae and 3.031 and 28.498 ppm against IV instar larvae of C. quinquefasciatus, respectively. Interestingly, the histological studies evidently showing the damage of peritrophic membrane and epithelial cells of testing mosquito larvae.

Potential targetability of multi-walled carbon nanotube loaded with silver nanoparticles photosynthesized from Ocimum tenuiflorum (tulsi extract) in fertility diagnosis.

Nanocarrier mediated targeted delivery and biosensing in reproductive health care is a major exploratory domain. This work demonstrates the loading of silver nanoparticle (AgNP) inside the multiwalled carbon nanotube (MWCNT) and their targetability to the intracellular part of the sperm cell for its further application in biosensing based infertility diagnosis. Ocimum tenuiflorum (tulsi extract) mediated photosynthesized AgNP exhibited spherical shape, 5-40 nm size and surface plasmonic resonance at 430 nm. After loading of freshly prepared AgNP into emulsified MWCNT, the loading was confirmed with spectroscopic and microscopic methods. FTIR analysis displayed significant shifting at 3450 cm-1 (-OH stretching) and 1615 cm-1 (CNT back bone) which validated the binding of AgNP with MWCNT and interestingly heat flow analysis revealed that Ag loaded MWCNT has greater stability than AgNP. Moreover, AFM based surface profile height analysis clearly showed the loading of AgNP inside MWCNT as surface height of MWCNT increased from 22 to 32 nm, which in turn confirmed the encapsulation of 10 nm size of AgNP inside the tube. Furthermore, surface enhanced Raman spectroscopy (SERS) confirmed the homogeneous loading as there were no changes in D/G ratio. SERS analysis for the interaction of AgNP loaded MWCNT with freshly collected healthy, motile human spermatozoa showed a significant Raman shift at 800-780 cm-1 (NH2+ twist) and 1050-1060 cm-1 (vas PO3-) for change in DNA packaging process and its stabilizing protein polyamine respectively. Finally, DNA fragmentation and morphological examination confirmed the binding and targetability of AgNP to the sperm nucleus. Improved targeting efficiency and biosenssing ability make AgNP-MWCNT composite suitable in fertility diagnosis.

Xenorhabdus stockiae KT835471-mediated feasible biosynthesis of metal nanoparticles for their antibacterial and cytotoxic activities.

In this study, extracellular metabolites of symbiotic bacteria Xenorhabdus stockiae (KT835471) was employed for the synthesis of silver (XsAgNPs) and gold nanoparticles (XsAuNPs). Synthesized NPs were characterized using high throughput instrumentation which confirms the generation of stable, crystalline XsAgNPs and XsAuNPs with the mean size of 14 ± 6 and 14 ± 5, respectively. Further, the NPs exhibits an excellent bactericidal effect against six different pathogens. On the other hand, NPs displayed an outstanding anticancer activity against human lung adenocarcinoma epithelial cells (A549). Therefore, the present study strongly suggests that metal NPs encrusted with functional bio-moieties can be used for different biomedical applications.