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Poly (acrylic acid) (PAA) nanocomposite hydrogel was fabricated as a sensing patch for non-invasive dual detection of urea in sweat. The hydrogel was prepared by γ-irradiation crosslinking of PAA solution incorporated with graphene oxide (GO) and cellulose nanofiber (CNF). With high water-sorption capacity and transparency, the hydrogel was suitable to accommodate coloring reagents and enzymes for colorimetric sensing of urea in sweat. The colorimetric sensor exhibited vivid color change towards the increase of urea concentration in a linear range of 40-80 mM covering a cut-off value (60 mM) for chronic kidney disease (CKD) indication. Furthermore, the hydrogel could be directly applied as a substrate for direct quantitation of urea in sweat by laser desorption ionization mass spectroscopy (LDI-MS). While CNF improved the mechanical properties of the hydrogel, GO played a key role in enhancing laser desorption ionization of urea in LDI-MS and increased the hydrogel functionalities. LDI-MS verified that GO/CNF/PAA hydrogel could act as a direct matrix for promoting urea ionization and these results corresponded well with the colorimetric sensor. Hence, this hydrogel patch might be a potential material to be applied in non-invasive and dual-detection of CKD in medical diagnosis., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The aim of this work is to prepare nanofibrous scaffolds based on poly (l-lactide-d, l-lactide)/poly (acrylic acid) [PLDLLA/PAAc] blends in the presence of Dexamethasone [Dexa]-loaded poly (2-hydroxyethyl methacrylate) [HEMA] as molecular imprinted polymer [MIP] nanoparticles [NPs] for enhancing osteogenesis. By adding 10 wt% of PAAc to the PLDLLA and employing response surface methodology, the average diameter of the electrospun nanofibers is approximately 237 nm. To increase the osteogenesis performance of the optimized nanofibrous scaffolds, the MIP nanoparticles are synthesized using HEMA monomer and Dexa template with a molar ratio of 10 to 1. Accordingly, these crosslinked drug nanocarriers exhibit an average diameter of around 122 nm and imprinting factor of approximately 1.8, enabling to adsorb Dexa molecules around 57%. Afterward, the Dexa-loaded MIP NPs have capability of a controlled drug release with ultimate value of 60% during 72 h. The simultaneous use of PLDLLA/PAAc-10 nanofibrous scaffold and Dexa-loaded MIP NPs within the cultivation media of fibroblast and mesenchymal stem cells is carried out by thiazolyl blue assay and acridine/ethidium bromide staining as well as alkaline phosphate/calcium content test, and alizarin red staining. The results reveal the remarkable efficiency of the blend nanofibers besides the MIP containing Dexa, thereby using for bone tissue engineering applications, potentially., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this pape., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Poly (l-lactide-co-D, l-lactide) (PLDLLA) is a biodegradable polymer predominantly used in biomedical applications. Despite unprecedented characteristics of PLDLLA, its wettability, mechanical properties, degradation, and cell attachment are main issues to improve. In this work, different blend films based on PLDLLA/poly (acrylic acid) (PAAc) are prepared to evaluate their miscibility, hydrophilicity, hydrolytic degradation and mechanical properties. For this purpose, a series of experiments such as DSC alongside SEM, water contact angle (WCA)/water up-take, weight measurements in phosphate buffer saline (PBS) and NaOH as well as tensile test are carried out. The DSC and SEM results show a miscibility for the blends, and hence by increasing PAAc, the WCA values and degradation rates are decreased and increased, respectively. Moreover, the degradation mechanisms of the blend samples follow surface/bulk erosion and bulk process in the alkaline and PBS environments, respectively. Subsequently, PLDLLA and its blends are electrospun to prepare nanofibrous samples, thereby assessing their cytotoxicity and cell viability by the use of thiazolyl blue assay and acridine orange/ethidium bromide staining, respectively. The in vitro SNL 76/7 fibroblast cells cultivation onto the surface of the blend with 10% wt. of PAAc revealed that this sample is a promising candidate for tissue engineering applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, nanofibers of poly (acrylic acid) (PAAc), polyacrylamide (PAAm) and poly (vinyl alcohol) (PVOH) were prepared using the electrospinning technique. Based on the Taguchi DOE (design of experiment) method, the effects of electrospinning parameters, i.e., needle tip to collector distance, polymer solution concentration, applied voltage, polymer solution feed rate and polymer type, on the diameter and morphology of polymer nanofibers were evaluated. Analyses of the experiments for the diameters of the polymer nanofibers showed that the type of polymer was the most significant factor. The optimal combination to obtain the smallest diameters with minimum deviations for electrospun polymer nanofibers was also determined. For this purpose, the appropriate factor levels were determined as follows: polymer PAAm, applied voltage 10 kV, delivery rate 0.1 mL/h, needle tip to collector distance 10 cm, and polymer solution concentration 8%, to obtain the thinnest nanofibers. This combination was further validated by conducting a confirmation experiment, and the average diameter of the polymer nanofibers was found to be close to the optimal conditions estimated by the Taguchi DOE method. [ABSTRACT FROM AUTHOR]

Quantifying the effect that nanofiber mat chemistry and hydrophilicity have on microorganism collection and inactivation is critical in biomedical applications. In this study, the collection and inactivation of Escherichia coli K12 was examined using cellulose nanofiber mats that were surface-functionalized using three polyelectrolytes: poly (acrylic acid) (PAA), chitosan (CS), and polydiallyldimethylammonium chloride (pDADMAC). The polyelectrolyte functionalized nanofiber mats retained the cylindrical morphology and average fiber diameter (~0.84 µm) of the underlying cellulose nanofibers. X-ray photoelectron spectroscopy (XPS) and contact angle measurements confirmed the presence of polycations or polyanions on the surface of the nanofiber mats. Both the control cellulose and pDADMAC-functionalized nanofiber mats exhibited a high collection of E. coli K12, which suggests that mat hydrophilicity may play a larger role than surface charge on cell collection. While the minimum concentration of polycations needed to inhibit E. coli K12 was 800 µg/mL for both CS and pDADMAC, once immobilized, pDADMAC-functionalized nanofiber mats exhibited a higher inactivation of E. coli K12, (~97%). Here, we demonstrate that the collection and inactivation of microorganisms by electrospun cellulose nanofiber mats can be tailored through a facile polyelectrolyte functionalization process. [ABSTRACT FROM AUTHOR]