Fabrication of nanocoated fibers for self-diagnosis of bacterial vaginosis

Characterization of permeability of electrospun yarns

We developed a novel technique enabling determination of the permeability of electrospun yarns composed of hundreds of fibers. Analyzing the wicking kinetics in a yarn-in-a-tube composite conduit, it was found that the kinetic is very specific. The liquid was pulled by the capillary pressure associated with the meniscus in the tube while the main resistance comes from the yarn. Therefore, one can separate the yarn permeability from the capillary pressure, which cannot be done in wicking experiments with single yarns. A surface tensiometer (Cahn) was employed to collect the data on wicking kinetics of hexadecane into the yarn-in-a-tube conduits. Yarns from different polymers and blends were electrospun and characterized using the proposed protocol. We showed that the permeability of electrospun yarns can be varied in a broad range from 10(-14) m(2) to 10(-12) m(2) by changing the fiber diameter and packing density. These results offer new applications of electrospun yarns as flexible micro- and nanofluidic systems.

Efficacy of methods used for the diagnosis of bacterial vaginosis

INTRODUCTION

Bacterial vaginosis (BV) has been associated with pelvic inflammatory disease, adverse pregnancy outcomes, increased susceptibility to sexually transmitted infections and infertility. Diagnosis of BV should be rapid, reliable and safe. This is especially vital in pregnant women where intervention may be necessary for the well-being of both the mother and the foetus.

AREAS COVERED

This paper consulted PUBMED, LISTA and Web of Science for point-of-care and laboratory-based tests commonly used for the diagnosis and management of BV in pregnant women. An overview of strengths and weaknesses of the methods used may partially explain why treatment plans have failed. Differences in sampling and detection methods, time of gestation, inter-examiner variability and interpretation of data, and the use of different reference tests, amongst many other factors, complicated a meta-analysis of the data.

EXPERT OPINION

Inconsistencies found in clinical and laboratory detection methods used for the monitoring of treatment have a direct impact on success rates. With current advances in technology, the diagnosis of BV is taking on a new perspective. New information implicating specific vaginal biofilms in adverse pregnancy outcomes through the application of advanced technology promises to change the way we view the aetiology, diagnosis and management of BV.

Toward fabric-based flexible microfluidic devices: pointed surface modification for pH sensitive liquid transport

Microfluidic fiber channels with switchable water transport are fabricated in flexible textile PET/PP materials using a preprogrammed yarn-based fabric and a yarn-selective surface modification method. The developed robust and scalable fabrication method is based on the selective functionalization of the PET yarns with an epoxide-containing polymer that is then followed by grafting patterns of different pH-sensitive polymers PAA [poly(acrylic acid) ] and P2VP [poly(2-vinyl pyridine)]. The selective functionalization of the fabric yields an array of amphiphilic channels that are constrained by hydrophobic PP boundaries. Aqueous solutions are transported in the amphiphilic channels by capillary forces where the direction of the liquid transport is defined by pH-response of the grafted polymers. The channels are fed with liquid through hydrophilic, pH insensitive PEG [polyethylene glycol] ports. The combination of the PAA and P2VP patterns in the amphiphilic channels is used to create pH-sensitive elements that redirect aqueous liquids toward PAA channels at pH > 4 and toward both PAA and P2VP channels at pH < 4. The system of pH-selective channels in the developed textile based microfluidic chip could find analytical applications and can be used for smart cloth.

Nanoporous artificial proboscis for probing minute amount of liquids

We describe a method of fabrication of nanoporous flexible probes which work as artificial proboscises. The challenge of making probes with fast absorption rates and good retention capacity was addressed theoretically and experimentally. This work shows that the probe should possess two levels of pore hierarchy: nanopores are needed to enhance the capillary action and micrometer pores are required to speed up fluid transport. The model of controlled fluid absorption was verified in experiments. We also demonstrated that the artificial proboscises can be remotely controlled by electric or magnetic fields. Using an artificial proboscis, one can approach a drop of hazardous liquid, absorb it and safely deliver it to an analytical device. With these materials, the paradigm of a stationary microfluidic platform can be shifted to the flexible structures that would allow one to pack multiple microfluidic sensors into a single fiber.

Absorption and transport properties of ultra-fine cellulose webs

Characterization of transport and absorption properties of nanofiber webs is a challenge, because in many cases the material is soft and cannot withstand the stresses exerted by the standard instruments. In this paper, we report on development of a new technique for materials characterization. We propose to conduct wicking and permeability experiments for full characterization of the nanowebs. As an example, we used electrospun cellulose acetate nanowebs. The wicking experiments showed very good reproducibility, demonstrating the square-root-of-time dependence of wetting front position vs time. The prefactor depends on a product of capillary pressure and materials permeability. We developed a technique to independently measure the permeability of small samples of nanowebs. Wicking and permeability data allow one to estimate the pore size; SEM micrographs confirmed the obtained estimates of pore radius. In general, the proposed method allows one to characterize the transport and absorption parameters of the nanofibrous materials for which the standard procedures are inapplicable.