Dissolvable Polyvinyl-Alcohol Film, a Time-Barrier to Modulate Sample Flow in a 3D-Printed Holder for Capillary Flow Paper Diagnostics

Abstract

Integrating a dissolvable membrane into a sensor allows the control of sample flow, location and duration in critical areas. These time-barrier films stop the flow of samples until the membrane has dissolved, thus, for example, allowing increased exposure time between immunoreagents for the formation of greater numbers of immuno-complexes, ensuring higher sensitivity, reactivity, and helping to reduce false-positive signals. In this study, dissolvable polyvinyl alcohol (PVA) films are used in a 3D-printed sensor holder, which enables film integration without the use of glue. PVA is a synthetic hydrophilic linear polymer, its solubility is dependent on its molecular weight and degree of hydrolysis. Three types of PVAs films were tested herein: (1) PVA 1-Mw: 30–70 K, 87–90% hydrolyzed; (2) PVA 2-Mw: 31–50 K, 98–99% hydrolyzed and (3) PVA 3-Mw: 89–98 K, >99% hydrolyzed. The films were exposed to water in (1) the novel 3D-printed holder and (2) directly immersed into a water droplet. After comparing the time taken to dissolve PVA 1–3 films, PVA 1 films of 5–20% (w/v) are found to be most suitable as time barrier films, due to their optimal dissolution times and physical properties for integration into the customized 3D-printed holder.

A review on lignocellulose/poly (vinyl alcohol) composites: cleaner approaches for greener materials

“…The higher viscosity can increase the adhesive strength and emulsion stabilisation of PVA which is suitable for use as an adhesive and surface coating. Higher tensile strength is also related to a higher M w of PVA due to the longer polymer chains (Harpaz et al 2019). In contrast, a lower M w of PVA tends to form hydrogen bonds in aqueous solutions (Hassan et al 2002) and has a higher solubility (Harpaz et al 2019).…”

“…Higher tensile strength is also related to a higher M w of PVA due to the longer polymer chains (Harpaz et al 2019). In contrast, a lower M w of PVA tends to form hydrogen bonds in aqueous solutions (Hassan et al 2002) and has a higher solubility (Harpaz et al 2019). However, even though the properties of PVA can differ by M w and DH and when used as a matrix, it can influence some important properties of composites (such as adhesive strength and water resistance), no specific trend is followed when it is selected for different LC/PVA materials.…”

Enhanced Colorimetric Signal for Accurate Signal Detection in Paper-Based Biosensors

“…Later, for a more accurate comparison between unstopped and stopped colorimetric signals detection in paper-based biosensors, the unstopped colorimetric signal on membrane was also examined. Subsequently, the stopped colorimetric signals were detected on membranes for paper-based biosensors, using a 'Stack-Pad' sensor layout [21][22][23], which consists of vertically stacked functional membranes ( Figure 1). The unstopped colorimetric signal was detected with and without the use of polyvinylidene difluoride (PVDF) [24] as a separation layer between the two functionalized layers of cellulose absorption pads, containing substrate and stop solution [25].…”

Characterization of a novel polyvinyl alcohol/chitosan porous hydrogel combined with bone marrow mesenchymal stem cells and its application in articular cartilage repair

“…Hydrogels have been used as a promising biomaterial in many biomedical applications such as drug delivery and tissue engineering in recent decades [7]. Polyvinyl alcohol (PVA) is a synthetic, biocompatible polymer that has been well studied for use in bioengineered tissue scaffolds due to its relatively high strength, creep resistance, water retention, and porous structure [8]. Chitosan (CS) is a linear, semi-crystalline and biocompatible polysaccharide.…”