Bioimaging Applications of Carbon dots (C. dots) and its Cystamine Functionalization for the Sensitive Detection of Cr(VI) in Aqueous Samples.

In this study, one step hydrothermal synthetic strategy was adopted for preparing carbon dots (C. dots) from jeera (Cumin: Cuminum cyminum), a naturally abundant and cost effective carbon source. The physical, optical and surface functional properties of C. dots were extensively studied by different techniques such as Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), spectrophotometry, fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The obtained C. dots were highly water dispersible and photostable with a quantum yield of 5.33%. The antioxidant property of C. dots was investigated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The C. dots were then capped with cystamine using 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) coupling chemistry to design a selective sensing system for chromium (VI) (Cr (VI)). The minimum detection limit of Cr (VI) was found to be 1.57 µM. Biocompatibility and low toxicity of C. dots obtained from jeera made it a potential tool for bioimaging application. The internalisation of C. dots by MCF-7 breast cancer cells and Multi Drug Resistant (MDR) pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa were proved by the bioimaging of respective cells.

Synergistic and antibiofilm potential of Curcuma aromatica derived silver nanoparticles in combination with antibiotics against multidrug-resistant pathogens.

Hospital acquired infections caused due to ESKAPE pathogens pose a challenge for treatment due to their growing antimicrobial resistance. Curcuma aromatica (CA) is traditionally known for its antibacterial, wound healing and anti-inflammatory properties. The present study highlights the biogenic synthesis of silver nanoparticles (CAAgNPs) capped and stabilized by the compounds from CA rhizome extract, also further demonstrating their antibacterial, antibiofilm and synergistic effects against multidrug-resistant (MDR) pathogens. CAAgNPs were synthesized using aqueous rhizome extract of CA (5 mg/ml) and AgNO3 (0.8 mM) incubated at 60°C up to 144 h. UV-vis spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) revealed CAAgNPs with characteristic peak at 430 nm, 13 ± 5 nm size of spherical shape, showing presence of silver and crystalline nature, respectively. Dynamic light scattering (DLS) and zeta potential confirmed their monodispersed nature with average diameter of 77.88 ± 48.60 nm and stability. Fourier transform infrared spectroscopic (FTIR) analysis demonstrated the presence of phenolic -OH and carbonyl groups possibly involved in the reduction and stabilization of CAAgNPs. The minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs) and minimum biofilm inhibitory concentrations (MBICs) of CAAgNPs against Pseudomonas aeruginosa, NCIM 5029 and PAW1, and, Staphylococcus aureus, NCIM 5021 and S8 were in range from 8 to 128 µg/ml. Almost 50% disruption of pre-formed biofilms at concentrations 8-1,024 µg/ml was observed. Fluorescence microscopy and FESEM analysis confirmed cell death and disruption of pre-formed biofilms of P. aeruginosa PAW1 and S. aureus S8. Checkerboard assay demonstrated the synergistic effect of CAAgNPs (0.125-4 µg/ml) in combination with various antibiotics (0.063-1,024 µg/ml) against planktonic and biofilm forms of P. aeruginosa PAW1. The study confirms the antibacterial and antibiofilm activity of CAAgNPs alone and in combination with antibiotics against MDR pathogens, thus, reducing the dose as well as toxicity of both. CAAgNPs have the potential to be used in wound dressings and ointments, and to improve the performances of medical devices and surgical implants. In vivo toxicity of CAAgNPs however needs to be tested further using mice models.

Antibiofilm and antipersister activity of acetic acid against extensively drug resistant Pseudomonas aeruginosa PAW1.

Pseudomonas aeruginosa is an ESKAPE pathogen associated with difficult-to-treat burn wound and surgical-site infections. This study aimed to characterise an extensively drug resistant (XDR) P. aeruginosa isolate (designated PAW1) and to investigate the antibiofilm and antipersister effect of acetic acid on PAW1. PAW1 was identified using biotypic (VITEK) and genotypic (16S rDNA) analysis. Minimum inhibitory concentration (MIC) and disc susceptibility testing showed high level resistance against all antibiotics from classes including beta lactams, cephems, carbapenems and fluoroquinolones. It was therefore identified as extensively drug resistant (XDR), showing resistance to all antibiotics except for, aminoglycoside (gentamicin and netilmicin) and lipopeptides (polymyxin B). Time kill assays showed antibiotic tolerant, persister cell formation in presence of 100X MICs of gentamicin and polymyxin B. Other virulence traits such as ability to produce lipase, protease, haemolysin, and siderophores and to form biofilms were additional factors which may contribute to its pathogenicity. PAW1 showed promising susceptibility against acetic acid with MIC and minimum biofilm inhibitory concentration of 0.156% (v/v). Percent viability of PAW1 was dependent on dose and treatment time of acetic acid. 0.625% acetic acid treatment of 5 minutes was effective in killing >90% planktonic cells showing lesser toxicity to L929 cells (IC50 = 0.625%). Biofilm disruption caused due to acetic acid was also dose dependent, showing 40.57% disruption after treatment with 0.625% acetic acid for 5 minutes. FESEM imaging and live dead staining of planktonic and biofilm forms of PAW1 confirmed that acetic acid treatment caused 19.04% of cell shrinkage and disruption of extracellular matrix resulting in killing of cells. Antipersister activity of acetic acid was demonstrated by showing complete killing of PAW1 at 4X MIC. Overall, this study characterised an XDR isolate P. aeruginosa showing resistance and tolerance to various antibiotics. Antipersister and antibiofilm effect of acetic acid demonstrates the importance of forgotten topical agents as an effective strategy to treat XDR pathogens.

Anticancer potential of AgNPs synthesized using Acinetobacter sp. and Curcuma aromatica against HeLa cell lines: A comparative study.

BACKGROUND: Biogenic nanoparticles are gaining attention due to their low toxicity and numerous biomedical applications. Present study aimed to compare the potential anticancer activity of two biogenic silver nanoparticles (bAgNPs and pAgNPs) against human cervical cancer cell lines (HeLa). METHODS: bAgNPs were synthesized using Acinetobacter sp. whereas pAgNPs were synthesized using aqueous root extract of Curcuma aromatica. Effect of these nanoparticles on HeLa cells viability was studied using MTT assay and colony formation assay. Anticancer potential was determined using fluorescence microscopy and flow cytometry studies. Bio-compatibility studies were performed against peripheral blood mononuclear cells (PBMCs). RESULTS: Both the nanoparticles showed 50 % viability of peripheral blood mononuclear cells (PBMCs) when used at high concentration (200 µg/mL). IC50 for bAgNPs and pAgNPs against HeLa cells were 17.4 and 14 µg/mL respectively. Colony formation ability of Hela cells was reduced on treatment with both nanoparticles. Acridine orange and ethidium bromide staining demonstrated that bAgNPs were cytostatic whereas pAgNPs were apoptotic. JC-1 dye staining revealed that the mitochondrial membrane potential was affected on treatment with pAgNPs while it remained unchanged on bAgNPs treatment. Flow cytometry confirmed cell cycle arrest in HeLa cells on treatment with nanoparticles further leading to apoptosis in case of pAgNPs. About 77 and 58 % HeLa cells were found in subG1 phase on treatment with bAgNPs and pAgNPs respectively. bAgNPs showed cytostatic effect on HeLa cells arresting the cell growth in subG1 phase, whereas, pAgNPs triggered death of HeLa cells through mitochondrial membrane potential impairment and apoptosis. CONCLUSION: Overall, bAgNPs and pAgNPs could be safe and showed potential to be used as anticancer nano-antibiotics against human cervical cancer cells.

Emerging Strategies to Combat ESKAPE Pathogens in the Era of Antimicrobial Resistance: A Review.

The acronym ESKAPE includes six nosocomial pathogens that exhibit multidrug resistance and virulence: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. Persistent use of antibiotics has provoked the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) bacteria, which render even the most effective drugs ineffective. Extended spectrum ß-lactamase (ESBL) and carbapenemase producing Gram negative bacteria have emerged as an important therapeutic challenge. Development of novel therapeutics to treat drug resistant infections, especially those caused by ESKAPE pathogens is the need of the hour. Alternative therapies such as use of antibiotics in combination or with adjuvants, bacteriophages, antimicrobial peptides, nanoparticles, and photodynamic light therapy are widely reported. Many reviews published till date describe these therapies with respect to the various agents used, their dosage details and mechanism of action against MDR pathogens but very few have focused specifically on ESKAPE. The objective of this review is to describe the alternative therapies reported to treat ESKAPE infections, their advantages and limitations, potential application in vivo, and status in clinical trials. The review further highlights the importance of a combinatorial approach, wherein two or more therapies are used in combination in order to overcome their individual limitations, additional studies on which are warranted, before translating them into clinical practice. These advances could possibly give an alternate solution or extend the lifetime of current antimicrobials.