First organic fluorescence immunoassay for the detection of Enterobacter cloacae in food matrixes.

For the first time, a novel fluorescent moiety, 2-amino-4-(7-formyl-1,8-dihydropyren-2-yl)-7-hydroxy-4H-chromene-3-carbonitrile (ACC), was synthesized by an ultrasonication method. The synthesis of this moiety was confirmed via structural elucidation using FTIR and NMR spectroscopy techniques. Further, photophysical properties of the fluorescent moiety were tested using UV-visible and emission spectroscopy techniques. In this case, the moiety was tagged with an antibody of Enterobacter cloacae via 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS) coupling and applied as a sensing element for the detection of Enterobacter cloacae (E. cloacae) by UV-visible and emission spectroscopy techniques. The developed fluorescent sensor detected E. cloacae via a FRET mechanism. Under optimized conditions, ACC-anti-E. cloacae detected E. cloacae in the linear range from 101 to 1010 CFU mL-1 with a limit of detection (LOD) of 10.55 CFU mL-1. The developed sensor was applied for the detection of E. cloacae in food samples such as orange, pomegranate, milk, rice, tomato, potato and onion.

Optical Immunosensor for the Detection of Listeria monocytogenes in Food Matrixes.

In this paper, simple imine-based organic fluorophore 4-amino-3-(anthracene-9 yl methyleneamino) phenyl (phenyl) methanone (APM) has been synthesized via a greener approach and the same was used to construct a fluorescent immunoassay for the detection of Listeria monocytogenes (LM). A monoclonal antibody of LM was tagged with APM via the conjugation of the amine group in APM and the acid group of anti-LM through EDC/NHS coupling. The designed immunoassay was optimized for the specific detection of LM in the presence of other interfering pathogens based on the aggregation-induced emission mechanism and the formation of aggregates and their morphology was confirmed with the help of scanning electron microscopy. Density functional theory studies were done to further support the sensing mechanism-based changes in the energy level distribution. All photophysical parameters were measured by using fluorescence spectroscopy techniques. Specific and competitive recognition of LM was done in the presence of other relevant pathogens. The immunoassay shows a linear appreciable range from 1.6 × 106-2.7024 × 108 cfu/mL using the standard plate count method. The LOD has been calculated from the linear equation and the value is found as 3.2 cfu/mL, and this is the lowest LOD value reported for the detection of LM so far. The practical applications of the immunoassay were demonstrated in various food samples, and their accuracy obtained was highly comparable with the standard existing ELISA method.

Extraction of Fucoidan from Turbinaria decurrens and the Synthesis of Fucoidan-Coated AgNPs for Anticoagulant Application.

Brown seaweeds usually contain alginate as a major polymer. The second major sulfated polymer in brown seaweeds is fucoidan, which has huge potential in medicinal applications. In this study, the photosynthetic pigments from Turbinaria decurrens were first extracted using chloroform/methanol in the ratio of 1:1 (v/v), followed by fucoidan extraction with yields of 5.58% (crude) and 1.28% (purified fucoidan) from the dry weight of seaweed, whereas alginate was extracted with a yield of 14.7% DW of seaweed. The isolated fucoidan possessing anticoagulation property was identified and characterized as (1-3)-α-l-fucopyranosyl residues with sulfate groups primarily at the C4 position and to a lesser extent at the C2 position, whereas in the case of galactose, at the C3 and C6 positions. The AgNPs synthesized using isolated fucoidan exhibit strong anticoagulant activity and possess a good antibacterial property against Gram-negative clinical bacteria. Functional groups such as O-H, C-H, and S=O associated with sugar residues in sulfated fucoidan are involved in the synthesis of the nanoparticles with a spherical shape, size ranging from 10 to 60 nm, and showing polydispersity. From this study, we conclude that fucoidan-coated anionic AgNPs synthesized from T. decurrens have tremendous potential in drug development.

Calcium alginate nanoparticle crosslinked phosphorylated polyallylamine to the controlled release of clindamycin for osteomyelitis treatment.

Osteomyelitis is one of the infections of the bone, and the treatment needs to the infection problems. Here, a local therapeutic approach for efficient drug delivery systems was designed to enhance the antibiotic drug's therapeutic activity. Calcium-Alginate nanoparticle (Ca-Alg) crosslinked phosphorylated polyallylamine (PPAA) was prepared through the salting-out technique, and it achieved 82.55% encapsulation of Clindamycin drug. The physicochemical characterizations of FTIR, SEM/EDX, TEM, and XRD were investigated to confirm the materials nature and formation. Clindamycin loaded Ca-Alg/PPAA system showed sustained Clindamycin release from the carrier. Cell viability was assessed in bone-related cells by Trypan blue assay and MTT assay analysis method. Both assay results exhibited better cell viability of synthesized materials against MG63 cells. MIC value of Ca-Alg/PPAA/Clindamycin in the Methicillin-resistant Staphylococcus aureus (MRSA) pathogen was 275 µg/mL, and it was 120 µg/mL for Enterobacter cloacae pathogen. The materials promising material for Osteomyelitis affected bone regeneration without any destructive effect and speedy recovery of infected parts from these investigations.

A promising drug delivery candidate (CS-g-PMDA-CYS-fused gold nanoparticles) for inhibition of multidrug-resistant uropathogenic Serratia marcescens.

Antibiotic resistance amongst microbial pathogens is a mounting serious issue in researchers and physicians. Various alternatives to overcome the multidrug-resistant bacterial infections are under search, and biofilm growth inhibition is one of them. In this investigation, a polymeric drug delivery system loaded with multi-serratial drugs to improve the delivery of drugs against urinary tract infection causative Serratia marcescens. The chitosan grafted pyromellitic dianhydride - cysteine (CS-g-PMDA-CYS) was conjugated with AuNPs by using the -SH group of CYS and RF (rifampicin) and INH (isoniazid) were loaded in AuNPs-fused CS-g-PMDA-CYS system. Several physicochemical techniques characterized this fabricated AuNPs/RF/INH/CS-g-PMDA-CYS system. The successful encapsulation of RF and INH in AuNPs-fused CS-g-PMDA-CYS polymer had confirmed, and it observed the loading capacity for RF and INH was 9.02% and 13.12%, respectively. The in vitro drug discharge pattern was perceived high in pH 5.5 compared with pH 7.4. The AuNPs/RF/INH/CS-g-PMDA-CYS escalates 74% of Caenorhabditis elegans survival during Serratia marcescens infection by aiming biofilm development and virulence in S. marcescens. Author postulate that the fabricated system is a promising drug carrier and delivery system for inhibition of multidrug-resistant bacterias like S. marcescens.

In vivo approach of simply constructed pyrazinamide conjugated chitosan-g-polycaprolactone micelles for methicillin resistance Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is an extensive origin of nosocomial infections that are very much challenging as well as complicated to eradicate mostly due to their strong resistance against all existing antibiotic therapies. Here the chitosan-grafted-polycaprolactone/maleic anhydride-pyrazinamide (CS-g-PCL/MA-PZA) polymeric drug carrier constructed via dialysis for anti-MRSA drugs like rifampicin (RF) and pyrazinamide (PZA) delivery. Nearly 200 nm size of the spherical particle with -20.04 mV of zeta potential observed. The cumulative PZA and RF releases from the carrier were observed 83.25% and 76.54% respectively in pH 5.5, and the in vitro drug release profile demonstrates that the fabricated micelle was pH-responsive. For the intestinal colonization, an in vivo assay performed using C. elegans, and the CS-g-PCL/MA-PZA/RF micelles treated worms generally belong to the weakly colonized category. Therefore, the study revealed that CS-g-PCL/MA-PZA/RF micelle could be a promising approach for therapeutic applications to achieve efficient anti-MRSA drug delivery.

Synthesis of Biogenic Copper Nanoparticles Embedded in Graphene Oxide-Chitosan Composite and Its Anti-Bacterial and Cytotoxic Activities.

In the current scenario, nanoparticle synthesis has been fascinated by biogenic approaches than the chemical methods. However, reproducibility of the source stands essentially in nanoparticle synthesis. Nanoparticle synthesis by fungi has more advantages such as the potential for bioaccumulation, immunity towards toxicity, relatively easier to handle, simpler in synthesis and downstream processing. In this study, biogenic copper nanoparticles (CuNPs) were embedded within graphene oxide-chitosan (GO-CS) polymer to endure the biocompatibility and toxicological effects on both normal and cancer cells. The characteristics of the copper nanoparticles/graphene oxide-chitosan (CuNPs/GO-CS) nanocomposites was found to be superior to the GO-CS. This is evident from the results obtained from X-ray diffraction technique, UV-visible spectroscopy, atomic force microscope, fourier transform infrared spectroscopy, fluorescence spectroscopy, confocal laser scanning microscope and scanning electron microscopy. The synthesized new copper nanoparticles/graphene oxide-chitosan (CuNPs/GO-CS) nanocomposites were studied for their anti-bacterial activity against Escherichia coli MTCC 443 and anti-cancer activity on breast cancer MCF7 cell lines.

Stimulus-responsive zinc oxide-functionalized macromolecular humic acid nanocarrier for enhancement of antibacterial activity of ciprofloxacin hydrochloride.

Macromolecular of naturally occurring humic acid (HA) have garnered interest in the chemical, biological and medicine industry owing to their unique behavior, i.e., strong adsorptive and non-toxic nature. Here, we investigated the functionalization of organic (HA) with inorganic (ZnO) hybrid nanoparticles for topical and site-targeted delivery of ciprofloxacin by simple emulsification techniques. Ciprofloxacin (CIPRO)-encapsulated hybrid nanocarrier constitute an attractive novel drug delivery vehicle for sustained release of antibiotics to bacterial infection sites in an extended and controlled manner. The analytical characteristics of the designed system were thoroughly investigated by FTIR, XRD, SEM/EDAX, and TEM. The drug release of ciprofloxacin over 24h was 87.5%, 98.03%, 97.44%, and 97.24% for pH2.5, 5.5, 6.8, and 8.0, respectively. The antibacterial activities results confirmed that the CIPRO-encapsulated hybrid nanocarrier showed excellent growth inhibition against microorganisms. This hybrid nanocarrier loaded with antibiotics represents a promising approach for targeted and controlled drug delivery to infected sites.

Transmission electron microscopic observations of membrane effects of antibiotic cecropin B on Escherichia coli.

The pathway of cell membrane lysis by the peptide antibiotic cecropin B (CB), which contains both a hydrophobic and an amphipathic alpha-helix, was analysed by assessing the morphological changes of Escherichia coli following treatment with the peptide. Exposure of green fluorescent protein (GFP)-expressing E. coli to CB does not lead to an efflux of GFP. Moreover, transmission electron microscopic (TEM) examination of cecropin B-treated cells showed that severe swelling precedes cell death and that the outer membrane becomes distended away from the plasma membrane. Using immuno-gold staining and TEM of E. coli expressing the maltose-binding protein in the cytoplasm, it was apparent that the protein remains restricted to the cytoplasmic compartment. These observations suggest that CB causes gross disruption of the outer membrane of Gram-negative bacteria. Circular dichroism measurements of CB in the presence of cell membrane-mimicking liposomes showed that CB forms secondary structure dependent on the ratio of [lipid]/[peptide]. These observations from this study are important for the future design of custom antimicrobial peptides.