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Influence of the Introduced Chitin Nanofibrils on Biomedical Properties of Chitosan-Based Materials

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Nguyễn Gia Hào

Academic year: 2023

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The functional groups of antibacterial natural products incorporated into PHBH composite nanofibers were analyzed using ATR (FT-IR). The FT-IR spectra of pure PHBH nanofibers and composite PHBH nanofibers with natural products showed similar peaks. Table 4 presents the inhibition zone diameters for composite PHBH nanofibers with natural products.

Overall, the natural products (especially propolis and hinokitiol) loaded into PHBH composite nanofibers inhibited the growth of S.

Table 1. The concentrations of natural products in each solution after dry vacuum and ratios of natural product solutions to total weight of spinning poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate]
Table 1. The concentrations of natural products in each solution after dry vacuum and ratios of natural product solutions to total weight of spinning poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate]

Conclusions

Caffeic Acid Phenethyl Ester Antimicrobial Medical Sutures and Their In Vitro/In Vivo Biological Assessment.Med. Biodegradable PHBH/PVA nanofibers: fabrication, characterization, in vitro degradation and in vitro biocompatibility.Polym. Poly(3-hydroxybutyrate)/caffeic acid electrospun fibrous material coated with polyelectrolyte complex and their antibacterial activity and in vitro antitumor effect against HeLa cells. Mater.

In vitro and in vivo wound healing studies of methanol fraction of Centella asiatica extract.S.

Influence of the Introduced Chitin Nanofibrils on Biomedical Properties of Chitosan-Based Materials

  • Introduction
  • Materials and Methods 1. Materials
  • Results
  • Discussion
  • Conclusions

The results of studies of hemostatic properties of chitosan sponges containing different amounts of ChNF are shown in Figure 3. It can be seen that all materials exhibit hemostatic properties, i.e. bleeding from the femoral artery stops faster than when the materials were not applied (control group). The introduction of ChNF in small amounts (0.5 wt%) leads to an increase in the surface potential of the composite fiber.

A sharp decrease in the potential occurs when the pH of the medium reaches the isoelectric point.

Figure 1. Non-woven material without chitin nanofibrils (ChNF) (left) and the material containing 0.5% ChNF (right).
Figure 1. Non-woven material without chitin nanofibrils (ChNF) (left) and the material containing 0.5% ChNF (right).

Plasma-Coated Polycaprolactone Nanofibers with Covalently Bonded Platelet-Rich Plasma Enhance

Materials and Methods

The effect of the PCL concentration on the electrospinning solution is shown in the top row of images in Figure 1, captured at the magnification of 10,000×. It can be seen that the effect of the applied stress on the fiber diameter is not linear. The immobilization of PRP also had no effect on the morphology of the PCL nanofibers.

The chemical composition of PCL nanofibers (PCL-ref) measured by XPS is reported in Table 1. At the same time, in PCL-COOH, the spreading level was practically independent of the number of cells per field. However, the larger size of some of the cells on PCL-COOH-PRP2 was the result of better adhesion and an earlier proliferation of fibroblasts.

The electrophilicity of the PCL-COOH surface, together with the negative charge of the cells, led to a delay in their interaction. The presence of divalent cations in the cell culture medium of the PCL-COOH surface allowed the cells to attach faster compared to the hydrophobic surface of PCL-ref. Throughout the experiment, a high level of fibroblast anoikis was observed on PCL-ref due to the surface adhesion deterioration [44] (see Figure 6 and Figure S3, Supplementary Materials).

Regardless of the type of bonding with PCL, the immobilization of PRP to PCL-ref and PCL-COOH leads to normal cell adhesion and proliferation due to the high biological activity of PRP components. A review of the effect of processing variables on the production of electrospun nanofibers for drug delivery applications.

Figure 1. SEM micrographs of the polycaprolactone (PCL-ref) nanofibers obtained from the PCL solutions with the different PCL concentrations and at different voltages
Figure 1. SEM micrographs of the polycaprolactone (PCL-ref) nanofibers obtained from the PCL solutions with the different PCL concentrations and at different voltages

Electrospun Polyvinylidene Fluoride-Based Fibrous Scaffolds with Piezoelectric Characteristics for Bone

Structural Behavior

The δ-phase has the same TGTG conformation of the macromolecular chains, but all dipoles are arranged parallel to each other, resulting in ferroelectric behavior. The α-phase can change to the β-phase under mechanical drawing, high-pressure annealing, and electric poling (Figure 3). The γ-phase also has an orthorhombic unit cell and is characterized by a sequence of trans and gauche conformation (T3GT3G).

P(VDF-TrFE) readily crystallizes from the melt and forms the β phase through copolymerization without stretching or mechanical pulling. The comonomer extends the cross-linking distance and reduces the activation energy for the α-phase to the β-phase. As mentioned above, nanoparticle additives can induce β-phase formation in PVDF by acting as effective nucleating agents.

They reported that the strong interfacial interactions between carbonyl group of GO and fluorine group (CF2) of PVDF led to the homogeneous distribution. The XRD pattern of β-PVDF exhibits a characteristic peak at 20.26◦ , which corresponds to the anomalous planes of (110) and (200). FTIR is particularly useful for identifying vibrational modes of the molecular chains of PVDF with different polymorphs, and for quantifying the amount of β-phase content.

However, the nonporous composite film prepared at 210 °C (F210-17NP) by melting and recrystallization had very low β-phase content; this film crystallized mainly into the α-phase. Thus, the processing temperature and electrospinning conditions are the main factors affecting the β-phase content in these nanocomposites [100].

Figure 2. Primary polymorphic crystalline phases of PVDF. Reproduced with permission from [50], published by Wiley-VCH, 2019.
Figure 2. Primary polymorphic crystalline phases of PVDF. Reproduced with permission from [50], published by Wiley-VCH, 2019.

Scaffold Fabrication

Schematic representation of the required properties of nanofibrous scaffolds, including geometry, mechanical capability, biocompatibility, and surface behavior. Stretching of the polymer jet induces the β-PVDF phase, ie. transformation of the non-polar α-phase into the polar β-phase. By adding more acetone (low DMF/acetone ratio), the rate of evaporation of the polymer/solvent solution tends to increase, resulting in the formation of more α-phase in the PVDF mats.

Lanceros-Méndez and colleagues also showed that the applied stress can produce a higher elongation of the polymer beam, which promotes the formation of β-phase [123]. A strong dependence of the fraction of β-phase in PVDF fibers on the applied voltage has also been reported by Sengupta et al. From Figure 13a, electrical (voltage/current) outputs of electrospun mats follow the increasing/decreasing trend of the β-phase content with the applied voltage.

The voltage/current outputs of PVDF fibers follow a similar changing trend of the β-phase content with spin distance. In this context, the fibers aligned near the collector can be bi-spliced ​​to opposite edges of the aperture. As a result, the d33 value of the PVDF/1 wt% MWCNT and PVDF/1 wt% (MWCNT-AgNP) fibrous mats increased significantly, especially the latter, with MWCNT-AgNP nanofillers (Table 1).

Compared to random fibers, aligned PVDF/MWCNT fibers exhibited the largest33 value of 31.3±2.1 pC/N due to the presence of the highest amount of the β-phase content (Table 1). Additional annealing, mechanical stretching or electrical poling can lead to a further improvement of the β-phase content.

Figure 7. Porous scaffolds produced by non-solvent induced phase separation (NIPS). Reproduced with permission from [112], published by Elsevier, 2015.
Figure 7. Porous scaffolds produced by non-solvent induced phase separation (NIPS). Reproduced with permission from [112], published by Elsevier, 2015.

In Vitro and In Vivo Models

As a result, osteoblasts cultured on hydrophilic PVDF fibrous scaffolds had better cell spreading over the non-treated counterparts as expected. On day 7, small round nodules were observed on the surfaces of osteoblasts cultured on both scaffolds. Consequently, the formation of mineralized collagen fibrils on the PVDF fibers can be adjusted by monitoring the surface potential of electrospun scaffolds.

Accumulation of collagen fibrils and calcium phosphate nodules on MG63 osteoblasts cultured on (c) PVDF(+) and (d) PVDF(-) scaffolds for seven days. Compared to in vitro cell culture studies, limited information is available on animal bone tissue responses to PVDF-based piezoelectric scaffolds in vivo. In addition, newly formed blood vessels were easily visible in the 1 wt% and 2 wt% nanocomposite scaffolds.

This was further enhanced by pre-seeding with hMSCs into the nanocomposite scaffolds prior to implantation (Figure 27b). In the context of neural tissue engineering, aligned electrospun fiber mats offer a clear advantage over the scaffolds with randomly oriented fibers. They reported that aligned P(VDF-TrFE) mats enhance SC growth and neurite expansion, especially for Matrigel-coated scaffolds (Figure 32a,b).

Therefore, Matrigel-filled aligned P(VDF-TrFE) carriers are useful for the treatment of peripheral nerve injury. Very few in vivo models have been performed on neural tissue responses to PVDF-based scaffolds.

Figure 20. (a) Relative ALP, (b) collagen I, and (c) osteopontin gene expressions of rBMSCs cultured on PPTi and NPTi samples for 14 days (n = 3)
Figure 20. (a) Relative ALP, (b) collagen I, and (c) osteopontin gene expressions of rBMSCs cultured on PPTi and NPTi samples for 14 days (n = 3)

Major Challenges

Nerves regenerated in pooled PVDF channels had a greater number of myelinated axons than those regenerated in non-pooled channels [198]. Very recently, Arinzeh and colleagues assessed the potential use of PVDF-TrFE conduits with SCs for in vivo spinal cord repair. The leads, with random or aligned fibrous inner walls, were transplanted into transected rat spinal cords for 3 weeks.

By optimizing PCL processing parameters, direct-write PCL scaffolds with fine filaments of 817 ± 165 nm can be produced. As mentioned, the non-polar α-phase is the dominant crystalline structure found in melt electrospun PVDF fibers [160]. Therefore, a major effort is required to solve the technical problems of forming melt electrospun 3D PVDF fiber mats containing electroactive β phase for tissue engineering applications.

Most literature studies have been limited to the use of PVDF-based 2D fibrous mats for in vitro cell culture. A systematic investigation of the cellular response to electrospun PVDF-based scaffolds in vivo, especially for bone and neural defects, is lacking. Currently, only a few studies have been performed on in vivo animal models of PVDF-based electrospun scaffolds and conduits.

For bone tissue engineering, an in-depth study and comprehensive understanding of animal models treated with the PVDF-based fibrous scaffolds is also lacking. The literature relating neuronal cell responses to the PVDF-based fibrous scaffolds in vivo is scarce.

Future Direction

Conclusions

Surface potential-controlled cell proliferation and collagen mineralization in electrospun polyvinylidene fluoride (PVDF) fiber scaffolds for bone regeneration.ACS Biomater. Nonwoven polyvinylidene fluoride 3D scaffolds: Fiber cross-section and texturing patterns influence mesenchymal stromal cell growth. Effect of pollutant condition and morphology of poly(vinylidene fluoride) piezoelectric membranes for skeletal muscle tissue engineering.RSC Adv.

Formation of piezoelectric β-phase crystallites in poly(vinylidene fluoride)-graphene oxide nanocomposites under uniaxial strain.J. Development of three-dimensional piezoelectric polyvinylidene fluoride-graphene oxide disorder by non-solvent-induced phase separation method for nervous tissue engineering. Mater. Effect of crystallization temperature on the crystal phase content and morphology of poly(vinylidene fluoride).J.

Modulation of the mechanical, physical and chemical properties of polyvinylidene fluoride disorder via non-solvent induced phase separation process for nervous tissue engineering applications.Eur. Electrospun poly(vinylidene fluoride-trifluoroethylene)/zinc oxide nanocomposite tissue engineering scaffolds with enhanced cell adhesion and blood vessel formation.Nano Res. The influence of piezoelectric scaffolds on neural differentiation of human neural stem/progenitor cells. Tissue Eng.

Effect of alignment of electrospun fibrous scaffolds on the biological behavior of RSC96 cells.J. Design and criteria of electrospun fibrous scaffolds for the treatment of spinal cord injuries. Neural Regen.

Hình ảnh

Figure 3. Wide-angle X-ray diffraction (WAXD) intensity profiles and 2D patterns of (A) neat PHBH and PHBH composite nanofibers with natural products: (B) EC, (C) MC, (D) EP, (E) EH.
Figure 4. Representative stress-strain curves of (A) neat PHBH and PHBH composite nanofibers with (B) EC, (C) MC, (D) EP, and (E) EH.
Figure 6. Cumulative release profiles of natural antibacterial products in PHBH composite nanofibers (A) PHBH/30EC (10%), (B) PHBH/30MC (10%), (C) PHBH/30EP (7%), and (D) PHBH/30EH (1%).
Figure 2. Blood absorbance by sponges vs. ChNF content in samples.
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