Cranberry proanthocyanidins composite electrospun nanofibers as a potential alternative for bacterial entrapment applications.

The interaction between A-type interflavan bonds from cranberry proanthocyanidins (PAC) and surface virulence factors of extra-intestinal pathogenic Escherichia coli (ExPEC) was studied. Electrospun nanofibers (ESNF) were fabricated using PAC and polycaprolactone (PCL) solutions and their physical and chemical properties were characterized. The ability of PAC:PCL composite ESNF to interact with and entrap ExPEC strain 5011 (ExPEC-5011) was evaluated in vitro by plate culturing and when formulated as a biofilter and nanocoating. As a biofilter, the PAC:PCL ESNF exhibited a dose-dependent ability to entrap ExPEC-5011. Images from scanning electron and fluorescent microscopies revealed that ESNF sections with higher amounts of PAC led to higher bacterial entrapment. The effectiveness PAC:PCL ESNF to bind ExPEC when applied as a nanocoating was studied using ESNF-coated polyvinyl chloride intermittent catheter. Results indicate that ExPEC-5011 was entrapped well into the PAC:PCL ESNF coating on the catheter. Overall, our results suggest that incorporating the biomolecule PAC in ESNF is a potential means for applications requiring bacterial entrapment, such as biofunctionalization, biofiltration, and surface coating, among others.

Cranberry Proanthocyanidins-PANI Nanocomposite for the Detection of Bacteria Associated with Urinary Tract Infections.

Consumption of cranberries is associated with the putative effects of preventing urinary tract infections (UTIs). Cranberry proanthocyanidins (PAC) contain unusual double A-type linkages, which are associated with strong interactions with surface virulence factors found on UTI-causing bacteria such as extra-intestinal pathogenic Escherichia coli (ExPEC), depicting in bacterial agglutination processes. In this work, we demonstrated the efficacy of cranberry PAC (200 µg/mL) to agglutinate ExPEC (5.0 × 108 CFU/mL) in vitro as a selective interaction for the design of functionalized biosensors for potential detection of UTIs. We fabricated functionalized screen-printed electrodes (SPEs) by modifying with PAC-polyaniline (PANI) nanocomposites and tested the effectiveness of the PAC-PANI/SPE biosensor for detecting the presence of ExPEC in aqueous suspensions. Results indicated that the PAC-PANI/SPE was highly sensitive (limit of quantification of 1 CFU/mL of ExPEC), and its response was linear over the concentration range of 1-70,000 CFU/mL, suggesting cranberry PAC-functionalized biosensors are an innovative alternative for the detection and diagnosis of ExPEC-associated UTIs. The biosensor was also highly selective, reproducible, and stable.

Composition of Anthocyanins and Proanthocyanidins in Three Tropical Vaccinium Species from Costa Rica.

Total polyphenol content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and proanthocyanidin (PAC) content were determined in fruit from three tropical Vaccinium species (Vaccinium consanguineum, Vaccinium floribundum, and Vaccinium poasanum) from Costa Rica sampled at three stages of fruit development. Results show that TAC increased as the fruit developed, while TPC, TFC, and PAC content decreased. Anthocyanin profiles were evaluated using electrospray ionization tandem mass spectrometry. Cyanidin and delphinidin glycosides were the predominant anthocyanins for the three tropical Vaccinium species. Proanthocyanidins were characterized using attenuated total reflection Fourier transform infrared spectroscopy, nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presence of procyanidin structures with B-type interflavan bonds were observed, but deconvolution of mass spectrometry isotope patterns indicated that PACs with one or more A-type interflavan bonds accounted for more than 74% of the oligomers at each degree of polymerization.

Non-covalent pomegranate (Punica granatum) hydrolyzable tannin-protein complexes modulate antigen uptake, processing and presentation by a T-cell hybridoma line co-cultured with murine peritoneal macrophages.

In this work we characterize the interaction of pomegranate hydrolyzable tannins (HT) with hen egg-white lysozyme (HEL) and determine the effects of non-covalent tannin-protein complexes on macrophage endocytosis, processing and presentation of antigen. We isolated HT from pomegranate and complex to HEL, the resulting non-covalent tannin-protein complex was characterized by gel electrophoresis and MALDI-TOF MS. Finally, cell culture studies and confocal microscopy imaging were conducted on the non-covalent pomegranate HT-HEL protein complexes to evaluate its effect on macrophage antigen uptake, processing and presentation to T-cell hybridomas. Our results indicate that non-covalent pomegranate HT-HEL protein complexes modulate uptake, processing and antigen presentation by mouse peritoneal macrophages. After 4 h of pre-incubation, only trace amounts of IL-2 were detected in the co-cultures treated with HEL alone, whereas a non-covalent pomegranate HT-HEL complex had already reached maximum IL-2 expression. Pomegranate HT may increase rate of endocytose of HEL and subsequent expression of IL-2 by the T-cell hybridomas.

In vitro uptake of lysozyme-loaded liposomes coated with chitosan biopolymer as model immunoadjuvants.

Chitosan binds to negatively charged soy lecithin liposomes by an electrostatic interaction driven by its cationic amino group. This interaction allows developing stable coated vesicles suitable as a targeted carrier and controlled release system for drugs and vaccines. In this work, we studied the effect of chitosan-coated liposomes on the uptake and antigen presentation of hen egg-white lysozyme (HEL) in Peyer's patches peritoneal macrophages isolated from mice. Chitosan-coated liposomes were characterized according to size, zeta potential, and antigen-loading and release properties. Results showed an increase in the positive net charge and size of the liposomes as the concentration of chitosan was increased, suggesting an electrostatic interaction and an effective coating, followed by fluorescence microscopy. About 85% of the antigen loaded remained in the chitosan-coated liposomes after release studies for 4 hours in phosphate-buffered saline. After 4 hours of preincubation with a T-cell hybridoma line cocultured with murine peritoneal macrophages, only trace amounts of interleukin-2 (IL-2) were detected in the cocultures treated with HEL alone, whereas cocultures treated with HEL-liposomes had an important production of IL-2, and the HEL chitosan-coated liposomes had already reached maximum IL-2 expression. Confocal microscopy studies showed that chitosan-coated liposomes had a higher uptake rate of the fluorescently labeled HEL than uncoated liposomal vesicles after 30 minutes of incubation with the peritoneal macrophages. Since uptake by macrophage cells is the first step in vaccination, our results suggest that the chitosan-coated liposomal system is a potential candidate as an immunoadjuvant for vaccine delivery systems.