Modulating the hAM/PCL Biocomposite for Expedited Wound Healing: A Chemical-Free Approach for Boosting Regenerative Potential.

There is an arising need for effective wound dressings that retain the bioactivity of a cellular treatment, but without the high costs and complexities associated with manufacturing, storing, and applying cell-based products. As skin wound recovery is a dynamic and complicated process, a significant obstacle to the healing of skin wounds is the lack of an appropriate wound dressing that can imitate the microenvironment of healthy skin and prevent bacterial infection. It requires the well-orchestrated integration of biological and molecular events. In this study, we have fabricated full-thickness skin graft biocomposite membranes to target full-thickness skin excision wounds. We reinforced human amniotic membrane (hAM) with electrospun polycaprolactone (PCL) to develop composite membranes, namely, PCL/hAM and PCL/hAM/PCL. Composite membranes were compared for physical, biological, and mechanical properties with the native counterpart. PCL/hAM and PCL/hAM/PCL displayed improved stability and delayed degradation, which further synergically improved the rapid wound healing property of hAM, driven primarily by wound closure analysis and histological assessment. Moreover, PCL/hAM displayed a comparable cellular interaction to hAM. On application as a wound dressing, histological analysis demonstrated that hAM and PCL/hAM promoted early epidermis and dermis formation. Studies on in vivo wound healing revealed that although hAM accelerates cell development, the overall wound healing process is similar in PCL/hAM. This finding is further supported by the immunohistochemical analysis of COL-1/COL-3, CD-31, and TGF-ß. Overall, this conjugated PCL and hAM-based membrane has considerable potential to be applied in skin wound healing. The facile fabrication of the PCL/hAM composite membrane provided the self-regenerating wound dressing with the desired mechanical strength as an ideal regenerative property for skin tissue regeneration.

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.

In Situ Functionalization of Cellulose with Zinc Pyrithione for Antimicrobial Applications.

Considering the public health demands for stronger and effective personal protective clothing, herein, antimicrobial fabrics using a known bacteriostatic and fungistatic drug zinc pyrithione (ZPT) have been reported. ZPT was synthesized in situ on cellulosic fabric, viscose (VC), using a zinc metal precursor and 2-mercaptopyridine-N-oxide as a ligand (VC-ZPT). For comparison, viscose was also phosphorylated (VP) before in situ functionalization with ZPT (VP-ZPT). Both approaches provided adequate protection from microbes; however, functionalization of cellulose with phosphate (VP) resulted in the formation of a linking group between cellulose and ZPT, which exhibited better uniformity of ZPT over the fabric surface and higher durability to washing. The functionalization was confirmed by inductively coupled plasma mass spectroscopy (ICP-MS), scanning electron microscopy (SEM), and Raman spectroscopy. Further, the bonding of phosphate with ZPT was confirmed by 31P solid-state NMR. The physical properties, such as appearance, bending length, and mechanical strength, of the treated fabrics remained unchanged. The antimicrobial activities of VP-ZPT with VC-ZPT were studied against Escherichia coli, Staphylococcus aureus, and Candida albicans, which were found to be effective until 20 laundry cycles in VP-ZPT. Additionally, VP-ZPT samples exhibited poor adherence of bacteria on the fabric surface. The functionalized fabrics may find applications for topical skin diseases in reducing the necessity of repeated use of antibiotic ointments.

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.

Metal-organic frameworks functionalized smart textiles for adsorptive removal of hazardous aromatic pollutants from ambient air.

Organic pollutants, with their increasing concentrations in the ambient air, are posing a severe threat to human health. Metal-organic frameworks (MOFs), due to their active functionalities and porous nature, have emerged as potential materials for the capture of organic pollutants and cleaning of the environment/air. In this work, the functionalization of cotton fabric is reported by the in-situ growth of zeolitic imidazolate framework (ZIF-8 and ZIF-67) MOFs on carboxymethylated cotton (CM Cotton) by employing a rapid and eco-friendly approach. The physicochemical characterization of the MOF functionalized fabrics (ZIF-8@CM Cotton and ZIF-67@CM Cotton) revealed uniform and wash durable attachment of porous ZIF nanocrystals on the surface of the fabric. These ZIF functionalized fabrics possessed high surface area and have been observed to adsorb significantly high concentrations of organic pollutants such as aniline, benzene, and styrene from ambient air. Interestingly these fabrics could be regenerated and reused repeatedly without any deterioration in their adsorption capacity. The negative and low binding energies calculated by DFT confirmed the physisorption of the aromatic pollutants on the surface of MOF functionalized fabrics. Such fabrics have a huge potential as protective textiles, anti-odor clothing, air purification filters, and related products.

A facile method for the phosphorylation of cellulosic fabric via atmospheric pressure plasma.

Green chemistry approach for phosphorylation of cellulose, under atmospheric pressure plasma was investigated and compared with conventional thermal method. The attachment of the phosphate groups was evaluated by 31P and 13C solid state NMR spectroscopy and XPS. The thermal method led to the formation of monophosphate of cellulose along with a side product of polymerized phosphate, whereas the plasma method produced only the monophosphate, without any side products. Unlike with the thermal treatment, the appearance and the mechanical properties of the viscose fabric remained nearly same after the plasma treatment. Also, the dyeability of the plasma modified fabric remained unchanged, whereas it decreased significantly in the thermally modified fabric. The amount of phosphate quantified by phosphomolybdate assay was found to be 2.88 ± 0.06 and 4.09 ± 0.19 % in the plasma and the thermal methods, respectively. This method has the potential to replace the existing methods of phosphorylation of cellulose.

Hydrophobic functionalization of cellulosic substrate by tetrafluoroethane dielectric barrier discharge plasma at atmospheric pressure.

Hydrophobic functionalization of cellulosic fabric (viscose) was carried out using helium/tetrafluoroethane (He/TFE) plasma, a commercially available fluorocarbon gas, at the atmospheric pressure. By selecting suitable plasma parameters, He/TFE plasma was produced and maintained in glow state so that the various fragments of TFE in plasma zone could react covalently with the cellulose. After the plasma treatment, the highly hydrophilic cellulosic fabric turned into superhydrophobic fabric with a water absorbency time of >> 60 min, a water contact angle of 153° and a water rolling angle of 5°. The functionalization was found to be wash durable to 25 laundry cycles. From the analyses of species present in plasma zone by optical emission spectroscopy (OES), gas-chromatography-mass spectrometry (GC-MS), and the chemical nature of the functionalized substrate by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), a possible mechanism involved in the reaction of TFE fragments with cellulose macromolecule was arrived at. Further, it could be inferred that the modification took place only at the surface of the fibres at the nanometre level. The study postulates that it is possible to elucidate reactions undergoing in plasma zone and to control them to achieve desirable modification of substrates.

Solution properties and electrospinning of poly(galacturonic acid) nanofibers.

Poly(galacturonic acid) (PGuA) is an important natural biopolymer, however its potential has not been realized due to its anionic nature and rigid structure, which limits its processability into fine films and fibres. This study aims at modifying the solution properties of PGuA in alkaline medium (aq. sodium hydroxide) to enable their conversion into electrospun nanofibers. Addition of anionic surfactants was found to play an important role in individualizing the PGuA chains that lead to formation of small spindle shaped fibers of length ranging from 2 to 10 µm and diameter from 287 to 997 nm. However, continuous fibers were not formed even at concentrations higher than the critical concentration. Addition of small amount (10-30%) of high molecular weight PVA resulted in formation of continuous fibers. Correlation of fiber diameters of PGuA/PVA with the rheological properties suggested a strong dependence of diameter with the elasticity of the blend solutions. Such PGuA based fibers may be utilized in various biomedical applications.

Readily dispersible antimicrobial Ag-SiO2 Janus particles and their application on cellulosic fabric.

Silver-silica (Ag-SiO2) Janus particles with varying functionalities i.e. amine, thiol and epoxy on the exposed surface of SiO2 particles were synthesized and explored for their antimicrobial activity. Due to their easy dispersibility, Janus particles with silver nanoparticles (AgNPs) of diameter ∼3 nm showed much lower minimum bactericidal concentration (MBC) as compared to conventional isotropic AgNPs powder having AgNPs of almost similar diameter. The isotropic AgNPs and functionalized Ag-SiO2 Janus particles were attached on cotton fabric using exhaustion method followed by curing. The treated fabrics were tested for their antimicrobial activity and wash durability. Ag-SiO2 Janus particles, due to the presence of various functionalities on one-half of their surface, could be attached to cellulosic substrates for imparting durable antimicrobial property.

Chitosan as a potential stabilizing agent for titania nanoparticle dispersions for preparation of multifunctional cotton fabric.

Titania (TiO2) nanoparticle dispersions in water were prepared using chitosan (CS) as the stabilizing agent. The dispersion stability was evaluated with respect to storage time, hydrodynamic particle size, and zeta potential. The effect of the molecular weight of CS and presence of non-ionic polymers (poly(vinyl alcohol) and poly(ethylene glycol)) as co-dispersants was investigated. Despite the increase in size of dispersed particles, the long-term storage stability of the dispersions improved with increasing concentration and molecular weight of CS. The TiO2/CS dispersions were applied on cotton fabric and characterized. The presence of CS did not seriously affect the photocatalytic self-cleaning activity (SCA) of TiO2; with CS, a SCA of 89% was achieved compared with a value of 96% without CS. In addition, the TiO2/CS-treated cotton fabrics provided UV protection and significant antimicrobial activity.

Zinc oxide nanorod assisted rapid single-step process for the conversion of electrospun poly(acrylonitrile) nanofibers to carbon nanofibers with a high graphitic content.

The effect of incorporation of rigid zinc oxide (ZnO) nanostructures on carbonization behavior of electrospun special acrylic fiber grade poly(acrylonitrile) (PAN-SAF) nanofibers was investigated. ZnO nanorods with high aspect ratios were incorporated into a PAN-N,N-dimethylformamide system and the composite nanofibers reinforced with aligned ZnO rods up to 50 wt% were successfully electrospun, and subsequently, carbonized. The morphology and the structural analysis of the resultant carbon nanofibers revealed that the rigid ZnO nanorods, present inside the nanofibers, possibly acted as scaffolds (temporary support structures) for immobilization of polymer chains and assisted in uniform heat distribution. This facilitated rapid and efficient conversion of the polymer structure to the ladder, and subsequently, the graphitized structure. At the end of the process, the ZnO nanorods were found to completely separate from the carbonized fibers yielding pure carbon nanofibers with a high graphitic content and surface area. The approach could be used to eliminate the slow, energy intensive stabilization step and achieve fast conversion of randomly laid carbon nanofiber webs in a single step to carbon nanofibers without the application of external tension or internal templates usually employed to achieve a high graphitic content in such systems.

Long-term preservation of donor corneas in glycerol for keratoplasty: exploring new protocols.

AIM: To evaluate the role of temperature and adjunctive dehydration in better long-term preservation of human corneas when preserved and stored in glycerol. METHODS: Different preservation temperatures and effects of adding silica gel in glycerol-preserved corneal tissues were evaluated. Human corneal tissues not suitable for optical keratoplasty initially preserved in McCarey-Kaufman medium were transferred to glycerol and stored at four different temperatures for 3 months as follows: tissues in anhydrous glycerol with and without silica gel at -80°C, -20°C, 4°C and at room temperature (RT). Parameters evaluated included microbial sterility, thickness (Digimatic micrometer), transparency (slit lamp examination, UV-Vis spectrophotometer), mechanical strength (Instron 5848 Microtester), tissue integrity (H&E staining), antigenicity (immunohistochemistry) and ultrastructure of collagen (transmission electron microscopy, TEM). RESULTS: Microbial test after 3 months of glycerol preservation confirmed sterility of the tissues. The thickness increased in corneas preserved at RT with and without silica gel (p<0.001). RT corneas had the lowest transparency and tensile strength. Tissues in anhydrous glycerol stored with and without silica gel at -80°C were the most transparent (p<0.001) and had the highest tensile strength (p<0.001). Tissue integrity was maintained and expression of Human Leukocyte Antigen D related (HLA-DR) was less in glycerol-preserved corneas at -80°C. TEM studies indicated that parallel alignment of stromal collagen was disrupted at RT-preserved corneas. CONCLUSIONS: Corneal tissue preserved at -80°C was the best method for preservation as it maintained the sterility, thickness, optical transparency, mechanical strength and ultrastructural features.

Surface-modified electrospun poly(epsilon-caprolactone) scaffold with improved optical transparency and bioactivity for damaged ocular surface reconstruction.

PURPOSE: The purpose of this study was to modify and functionalize the surface of synthetic poly-ε-caprolactone (PCL) nanofibrous scaffolds to improve their biocompatibility in order to provide better "cell-substrate" interaction. METHODS: Poly-ε-caprolactone solution was electrospun and its surface functionality was modified by helium-oxygen (He/O2) plasma discharge. Scaffolds were characterized for their morphology, wetting ability, mechanical strength, and optical properties by using scanning electron microscopy (SEM), water contact angle measurement, tensile strength, and ultraviolet-visible (UV-Vis) spectrophotometer, respectively. The biocompatibility of nanofibers was explored by culturing human corneal epithelial (HCE-T) cell line. Subsequently, human limbal epithelial cells (LECs) were cultured to evaluate the bioactivity. Cell proliferation was checked by MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Immunofluorescent staining and reverse transcription-polymerase chain reaction were done to check the gene expression; SEM was used to study the morphology. RESULTS: Plasma-treated and untreated scaffolds showed almost similar morphology and tensile strength. Water contact angle measurement and optical transparency data showed that the plasma-treated PCL (pPCL) exhibited significantly improved wettability and transparency as compared to the untreated PCL scaffolds. Biocompatibility results indicated that both scaffolds are biocompatible in terms of cell survival and proliferation. However, pPCL showed better cell adhesion and proliferation. Results supported that LEC cultured on pPCL scaffolds had enhanced cell adhesion and proliferation, in comparison to untreated PCL. Gene expression study showed cultures were able to retain their normal phenotype on both scaffolds. CONCLUSIONS: The hydrophilicity of the surface achieved by plasma treatment effectively enhanced the transparency and promoted the biocompatibility of scaffolds. These nanofibers may act as biological cues for endorsing ocular surface engineering.

Bi-layer composite dressing of gelatin nanofibrous mat and poly vinyl alcohol hydrogel for drug delivery and wound healing application: in-vitro and in-vivo studies.

Present investigation involves the development of a bi-layer dressing of gelatin nanofibrous mat loaded with epigallocatechin gallate (EGCG)/poly vinyl alcohol (PVA) hydrogel and its in-vivo evaluation on full-thickness excision wounds in experimental Wistar rats. Nanomorphological observation, porosity, effect of crosslinking on tensile strength, physical stability and drug release profile in phosphate buffer and biocompatibility aspects of electrospun nanomat were investigated by various physico-chemical tools. EGCGa release profile was found to increase from 2-4 days with decreasing crosslinking time from 15 to 5 min. PVA hydrogels were prepared by freeze-thaw method and has been utilized as a protective and hydrating outer layer of the bi-layer dressing. Topical application of bi-layer composite dressing loaded with EGCG improve the healing rate in experimental rats as acute wounds model which was evidenced by significant increase in DNA (approximately 42%), total protein (approximately 32%), hydroxyproline (approximately 26%) and hexosamine approximately 24%) contents. A faster wound contraction was observed in wounds treated with composite dressing from approximately 14% to 47%. Histopathological examination revealed significant improvement in angiogenesis, re-epithelialization and less inflammatory response in comparison to control. Van-Gieson's collagen stains revealed matured, compact and parallel deposition of collagen fibrils on day 12. These results were supported by up-regulated expressions of matrix metalloproteinase (MMPs-2 and 9) by gelatin zymography. Control release of EGCG, 3D porous architecture of nanofibrous scaffolds as well as moist microenvironment provides ideal conditions for uninterrupted wound healing.

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.