Portable Nanofiber-Light Addressable Potentiometric Sensor for Rapid Escherichia coli Detection in Orange Juice.

The growing need to prevent pathogen outbreaks is irrefutable in the case of the food industry. Early detection in products, especially beverages, contaminated with bacterial strains is vital to avoid infected foods from reaching the consumer. If E. coli is pesent in such foods, it can cause infections. It can also be an indicator of the existence of other harmful coliforms. In this study, we have investigated the detection of Escherichia coli ( E. coli) in orange juice using a portable nanofiber-light addressable potentiometric sensor (NF-LAPS). We have chosen electrospun pH-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) hydrogel NFs as the sensitive layer. The successful detection of E. coli was reported with the NF-LAPS in less than 1 h. The limit of detection (LOD) measured in the sensor is found to be102 CFU/mL. We have confirmed the selectivity of the biosensor toward E. coli by examining the response of the NF-LAPS against Salmonella typhimurium ( S. typhi), also commonly found in orange juice. Despite the complex nature of orange juice, the response of the biosensor is in no way affected while orange juice is tested as is.

Metabolic Study of Cancer Cells Using a pH Sensitive Hydrogel Nanofiber Light Addressable Potentiometric Sensor.

We report a simple, fast, and cost-effective approach that measures cancer cell metabolism and their response to anticancer drugs in real time. Using a Light Addressable Potentiometric Sensor integrated with pH sensitive hydrogel nanofibers (NF-LAPS), we detect localized changes in pH of the media as cancer cells consume glucose and release lactate. NF-LAPS shows a sensitivity response of 74 mV/pH for cancer cells. Cancer cells (MDA MB231) showed a response of ∼0.4 unit change in pH compared to virtually no change observed for normal cells (MCF10A). We also observed a drop in pH for the multidrug-resistant cancer cells (MDA-MB-435MDR) in the presence of doxorubicin. However, inhibition of the metabolic enzymes such as hexokinase and lactate dehydrogenase-A suggested an improvement in the efficacy of doxorubicin by decreasing the level of acidification. This approach, based on extracellular acidification, enhances our understanding of cancer cell metabolic modes and their response to chemotherapies, which will help in the development of better treatments, including choice of drugs and dosages.

Rapid and Highly Sensitive Detection of Dopamine Using Conjugated Oxaborole-Based Polymer and Glycopolymer Systems.

A conjugated polymer interface consisting of an oxaborole containing polymer and a glycopolymer was used for achieving very high selectivity in dopamine (DA) detection. The optimum binding affinity between the polymers promotes the selectivity to DA through a displacement mechanism while remaining unaffected by other structurally related analogs and saccharide derivatives. Real-time detection of DA with very high selectivity and sensitivity has been demonstrated by immobilizing the polymer conjugates on surface plasmon resonance (SPR) and microcantilever (MCL) sensor platforms. Using the conjugated polymer sensing layer, the SPR biosensor was capable of detecting DA in the concentration range of 1 × 10-9 to 1 × 10-4 mol L-1, whereas the MCL sensor showed a limit of detection (LOD) of 5 × 10-11 mol L-1. We find that the sensing mechanism is based on DA-induced reversible swelling of the conjugated polymer layer and this allows regeneration and reuse of the sensor multiple times. Also, we conclude that SPR is a suitable sensor platform for DA in-line detection at clinical level considering the detection time and stability, whereas MCL can achieve a much lower LOD.

Polyethylene glycol-modified gelatin/polylactic acid nanoparticles for enhanced photodynamic efficacy of a hypocrellin derivative in vitro.

The present study focused on the development of a novel biodegradable nanoparticle system based on polyethyleneglycol-modified gelatin (PEG-GEL) and polylactic acid (PLA) biopolymers for improving the photodynamic efficacy of cyclohexane-1,2-diamino hypocrellin B (CHA2HB), a potent photodynamic therapeutic (PDT) agent. The CHA2HB-loaded PEG-GEL/PLA nanoparticles showed near-spherical morphology with an average size of 190 nm at a PLA to PEG-GEL ratio of 1:3. The drug loading was sufficient enough to produce potentially toxic reactive oxygen species (ROS) needed for photodynamic therapy (PDT). Slow and controlled drug release was observed in normal conditions, whereas enzyme assistance resulted in a relatively fast release due to partial disintegration of CHA2HB-loaded PEG-GEL/PLA nanoparticles. In vitro experiments indicated that CHA2HB-loaded PEG-GEL-PLA nanoparticles are efficiently taken up by cancer cells such as human breast adenocarcinoma (MCF-7), human gastric sarcoma (AGS) and mice specific Dalton's lymphoma (DLA) in a time dependent manner. Further, CHA2HB-loaded PEG-GEL/PLA nanoparticles evoked superior phototoxicity compared to free-CHA2HB towards all the three cell lines investigated. Interestingly, PDT effectiveness was different for the different cell type studied. CHA2HB-loaded PEG-GEL/PLA nanoparticles induced both apoptotic and necrotic cell death as a result of photoirradiation. Thus, our data suggest that PEG-GEL/PLA nanoparticles are highly effective in delivery and phototoxic enhancement of CHA2HB against model cancer cells in vitro.

Biophysical evaluation of two red-shifted hypocrellin B derivatives as novel PDT agents.

Two novel cyclohexane-1,2-diamino and N,N dimethyl amino-propyl substituted hypocrellin B derivatives, abbreviated as CHA2HB and DMAHB, respectively were synthesized. These derivatives exhibited enhanced absorption in phototherapeutic window. Photodynamic action of these derivatives, investigated using optical and electron spin resonance methods, depended on both Type I and Type II mechanisms. Gel electrophoresis indicated 1O2/O2(.-) mediated DNA damage. CHA2HB displayed 20 fold increase in light dependent cytotoxicity on colon cancer cell line (HCT 116) than the well-known hypocrellin B (HB). The light induced, LD(50) values for CHA2HB and DMAHB were found to be 0.1 microM and 1.5 microM, respectively. The singlet oxygen generating efficiency followed the order HB>CHA(2)HB>DMAHB. But, the enhanced red absorption as well as the hydrophilicity renders the CHA2HB a better photodynamic therapeutic agent.

Amelioration of accelerated collagen induced arthritis by a novel calcineurin inhibitor, ISA(TX)247.

OBJECTIVE: To examine the efficacy and toxicity of ISA(TX)247, a novel calcineurin inhibitor, in comparison to cyclosporine (cyclosporin A, CSA) and placebo in established collagen induced arthritis. ISA(TX)247 has up to 3-fold greater potency than CSA in an in vitro whole blood calcineurin inhibition assay and in in vivo solid organ and cell transplantation models. Phase I clinical trials show no discernible nephrotoxicity. METHODS: Type II collagen immunized DBA/Lac J mice with established arthritis were randomized to treatment with ISA(TX)247 (125/250/500 microg/mouse), CSA (250/500 microg/mouse), or drug vehicle, by daily intraperitoneal injection for 10 days from the onset of clinical arthritis. RESULTS: A significant dose dependent reduction in clinical severity was observed in ISA(TX)247 treated but not in CSA treated animals 10 days after the onset of established arthritis, and when examined by area under the curve analysis during the treatment period. Significant improvement in paw swelling (p < 0.001), synovial histology (p < 0.001), and articular cartilage damage scores (p = 0.002) was also noted in ISA(TX)247 treated animals, even in the 125 pg dose group (p = 0.03 for paw swelling and synovial histology). By comparison, CSA had no significant effect on either synovial inflammation or articular cartilage damage. ISA(TX)247 (500 microg dose group) was the only treatment to significantly decrease the development of proximal interphalangeal joint erosions (p < 0.05). A significant reduction in Type II collagen antibody titer was noted in ISA(TX)247 animals in both 250 microg (p = 0.02) and 500 microg (p = 0.004) dosage groups, but only in the 500 microg group for CSA (p = 0.004). Treatment was well tolerated, with no significant toxicity in ISA(TX)247 groups. CONCLUSION: ISA(TX)247 demonstrates efficacy and safety in the treatment of established collagen induced arthritis. Together with its improved potency and nephrotoxicity profile in comparison to CSA, this agent warrants further clinical investigation in autoimmune disease. Phase II studies in rheumatoid arthritis have been initiated.