Biocompatible dressing for pediatric hypospadias repair.

PURPOSE: The search for an ideal Hypospadias repair dressing continues. We aimed to develop a hypoallergenic optimized biocompatible dressing (BD). METHOD: BD with a multi-layered structure of hydrophilic treated Polypropylene with three-layered technologies; Absorbent-spunlaced hydroentangled polyester/viscose blend, outer Polypropylene, Polyester, Acrylic, and Spandex, with super Absorbent Polymer and Acrylic adhesive. Wistar rat abdominal wound model was divided into two groups: control (normal gauze dressing with adhesive) and Study (BD). The physical properties and wound characteristics were compared. RESULTS: Average mass: thickness of BD was 626.7 ± 5.6 g m-2: 2.6 ± 0.015 mm. Absorption was 1425.2 ± 127.6%. Percentage desorption of solution A from dressings at 24:40 h was 1249 ± 150%:1417 ± 230%. BD was hydrophilic with no particles/residue after immersion and pH neutral. The average air permeability was 11.6 ± 1.6 cm3/cm2/sec. The tensile force was 200N-220N with an extension on the breaking point at 24 mm. BD was superior for ease of removability on Day 6 (p = 0.012) and sticking quality (p = 0.036), absorption (p = 0.036), ease of removability(p = 0.036), and sustenance (p = 0.030) on Day 10. BD dressing demonstrated better wound healing (p = 0.015) and decreased redness (p = 0.002) on Day 10. Histopathological healing was better with BD on Day 14(p = 0.025) and Day 20 (p = 0.034). CONCLUSION: BD demonstrated better desirable physical and wound healing qualities with less inflammation compared with control normal dressing.

Unfolding the effects of decontamination treatments on the structural and functional integrity of N95 respirators via numerical simulations.

Filtering facepiece respirators (FFRs) provide effective protection against diseases spread through airborne infectious droplets and particles. The widespread use of FFRs during the COVID-19 pandemic has not only led to supply shortages, but the disposal of single-use facemasks also threatens the environment with a new kind of plastic pollution. While limited reuse of filtering facepiece respirators has been permitted as a crisis capacity strategy, there are currently no standard test methods available for decontamination before their repeated use. The decontamination of respirators can compromise the structural and functional integrity by reducing the filtration efficiency and breathability. Digital segmentation of X-ray microcomputed tomography (microCT) scans of the meltblown nonwoven layers of a specific N95 respirator model (Venus-4400) after treatment with one and five cycles of liquid hydrogen peroxide, ultraviolet radiation, moist heat, and aqueous soap solution enabled us to perform filtration simulations of decontaminated respirators. The computed filtration efficiencies for 0.3 µm particles agreed well with experimental measurements, and the distribution of particle penetration depths was correlated with the structural changes resulting from decontamination. The combination of X-ray microCT imaging with numerical simulations thus provides a strategy for quantitative evaluation of the effectiveness of decontamination treatments for a specific respirator model.

Graphene nanofiber composites for enhanced neuronal differentiation of human mesenchymal stem cells.

Aim: To differentiate mesenchymal stem cells into functional dopaminergic neurons using an electrospun polycaprolactone (PCL) and graphene (G) nanocomposite. Methods: A one-step approach was used to electrospin the PCL nanocomposite, with varying G concentrations, followed by evaluating their biocompatibility and neuronal differentiation. Results: PCL with exiguous graphene demonstrated an ideal nanotopography with an unprecedented combination of guidance stimuli and substrate cues, aiding the enhanced differentiation of mesenchymal stem cells into dopaminergic neurons. These newly differentiated neurons were seen to exhibit unique neuronal arborization, enhanced intracellular Ca2+ influx and dopamine secretion. Conclusion: Having cost-effective fabrication and room-temperature storage, the PCL-G nanocomposites could pave the way for enhanced neuronal differentiation, thereby opening a new horizon for an array of applications in neural regenerative medicine.

Cellular response of limbal epithelial cells on electrospun poly-ε-caprolactone nanofibrous scaffolds for ocular surface bioengineering: a preliminary in vitro study.

PURPOSE: The aim of this study was to develop a synthetic stromal substrate for limbal epithelial cell (LEC) expansion that can serve as a potential alternative substrate to replace human amniotic membrane (HAM). METHODS: Nanofibers were fabricated using 10% poly-ε-caprolactone (PCL) solution dissolved in trifluoroethanol (TFE) via an electrospinning process. Nanofibers were characterized for surface morphology, wetting ability, pore size, mechanical strength, and optical transparency using scanning electron microscopy (SEM), contact angle measurement, microtensile tester, and UV-Vis spectrophotometer, respectively. The human corneal epithelial (HCE-T) cell line was used to evaluate the biocompatibility of nanofibers based on their phenotypic profile, viability, proliferation, and attachment ability. Subsequently, human LECs were cultivated on biocompatible nanofibers for two weeks and their proliferation capability analyzed using MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole)) proliferation assay. Immunofluorescent (IF) staining and reverse transcriptase polymerase chain reaction (RT-PCR) were performed to check the molecular marker expression; SEM was used to study the morphology. RESULTS: The average fiber diameter of PCL was 132±42 nm. Pore size varied from 0.2 to 4 microns with a porosity of 85%. The tensile strength of the PCL membrane was 1.74±0.18 MPa (Mega Pascal); strain was 30.08±2.66%. The water contact angle was 90°. Biocompatibility results indicated that the polymer surface was highly biocompatible, as HCE-T cells could favorably attach and proliferate on the polymer surface. SEM figures showed that the corneal epithelium was firmly anchored to the polymer surface via a continuous cell sheet and was able to retain a normal corneal phenotype. MTT assay confirmed that cells were metabolically active on nanofibers (p<0.05) and gradually increased in their number for up to two weeks. IF and RT-PCR results revealed no change in the expression profile of LECs grown on nanofibers when compared to those grown on glass coverslips and human amniotic membrane (HAM). Confocal microscopy illustrated that cells infiltrated the nanofibers and successfully formed a three-dimensional (3D) corneal epithelium, which was viable for two weeks. CONCLUSIONS: Electrospun nanofibers provide not only a milieu supporting LEC expansion, but also serve as a useful alternative carrier for ocular surface tissue engineering and could be used as an alternative substrate to HAM.