Chitosan Gelatin Research Articles

Multifunctional palygorskite@ZnO nanorods enhance simultaneously mechanical strength and antibacterial properties of chitosan-based film

A general and effective strategy was developed for improving simultaneously the mechanical strength and antibacterial performance of biopolymer-based films. The well-dispersed zinc oxide (ZnO) nanoparticles were in-situ loaded on non-toxic natural palygorskite (PAL) nanorod to form an antibacterial PAL@ZnO composite nanorod, which can be embedded into chitosan/gelatin (CS/GL) film to produce the composite films with noticeably enhanced mechanical properties and antibacterial activity against S. aureus and E. coli bacteria (inhibition zones are 21.82 ± 0.95 mm and 16.36 ± 1.64 mm, respectively). The toughness of films enhances to 35.13 ± 0.95 MPa and the moisture uptake decreases to 23.74 ± 0.02% after embedding 3% and 9% of PAL@ZnO, respectively. In addition, incorporating PAL@ZnO nanorods also significantly enhanced the water resistance, and thermal stability of film. This work provides an alternative way for the development of antibacterial films with potential applications in many fields such as food packing.

Fabrication and Evaluation of Alginate/Bacterial Cellulose Nanocrystals-Chitosan-Gelatin Composite Scaffolds.

It is common knowledge that pure alginate hydrogel is more likely to have weak mechanical strength, a lack of cell recognition sites, extensive swelling and uncontrolled degradation, and thus be unable to satisfy the demands of the ideal scaffold. To address these problems, we attempted to fabricate alginate/bacterial cellulose nanocrystals-chitosan-gelatin (Alg/BCNs-CS-GT) composite scaffolds using the combined method involving the incorporation of BCNs in the alginate matrix, internal gelation through the hydroxyapatite-d-glucono-δ-lactone (HAP-GDL) complex, and layer-by-layer (LBL) electrostatic assembly of polyelectrolytes. Meanwhile, the effect of various contents of BCNs on the scaffold morphology, porosity, mechanical properties, and swelling and degradation behavior was investigated. The experimental results showed that the fabricated Alg/BCNs-CS-GT composite scaffolds exhibited regular 3D morphologies and well-developed pore structures. With the increase in BCNs content, the pore size of Alg/BCNs-CS-GT composite scaffolds was gradually reduced from 200 μm to 70 μm. Furthermore, BCNs were fully embedded in the alginate matrix through the intermolecular hydrogen bond with alginate. Moreover, the addition of BCNs could effectively control the swelling and biodegradation of the Alg/BCNs-CS-GT composite scaffolds. Furthermore, the in vitro cytotoxicity studies indicated that the porous fiber network of BCNs could fully mimic the extracellular matrix structure, which promoted the adhesion and spreading of MG63 cells and MC3T3-E1 cells on the Alg/BCNs-CS-GT composite scaffolds. In addition, these cells could grow in the 3D-porous structure of composite scaffolds, which exhibited good proliferative viability. Based on the effect of BCNs on the cytocompatibility of composite scaffolds, the optimum BCNs content for the Alg/BCNs-CS-GT composite scaffolds was 0.2% (w/v). On the basis of good merits, such as regular 3D morphology, well-developed pore structure, controlled swelling and biodegradation behavior, and good cytocompatibility, the Alg/BCNs-CS-GT composite scaffolds may exhibit great potential as the ideal scaffold in the bone tissue engineering field.

Effect of glutaraldehyde on the characteristics of chitosan–gelatin–β-tricalcium phosphate composite scaffolds

A composite scaffold was successfully fabricated using β-tricalcium phosphate (βTCP), which is extracted from limestone by first sintering and then reacting it with phosphoric acid through wet precipitation method. The resultant substance is then mixed with chitosan and gelatin. This novel method utilizes limestone, which is abundant in nature. This study optimizes the composite scaffold fabrication by using βTCP from limestone and evaluating the effect of glutaraldehyde on scaffold characteristics. The freeze-drying method was used to obtain a porous scaffold. The compressive strength of the cross-linked scaffolds (3.3 ± 0.3 MPa) was significantly higher than that of scaffolds without glutaraldehyde (1.7 ± 0.2 MPa). In contrast, the porosity of the cross-linked scaffolds was lower (85.8 ± 0.8 %) than the non-cross-linked scaffolds (89.1 ± 0.4 %). It is clear that the porosity had a considerable impact on the compressive strength, wherein lower porosity led to a higher compressive strength. In conclusion, glutaraldehyde is an effective cross-linker for the fabrication of chitosan–gelatin–βTCP composite scaffolds and significantly improves their compressive strength.

Review of Applications and Future Prospects of Stimuli-Responsive Hydrogel Based on Thermo-Responsive Biopolymers in Drug Delivery Systems.

Some of thermo-responsive polysaccharides, namely, cellulose, xyloglucan, and chitosan, and protein-like gelatin or elastin-like polypeptides can exhibit temperature dependent sol–gel transitions. Due to their biodegradability, biocompatibility, and non-toxicity, such biomaterials are becoming popular for drug delivery and tissue engineering applications. This paper aims to review the properties of sol–gel transition, mechanical strength, drug release (bioavailability of drugs), and cytotoxicity of stimuli-responsive hydrogel made of thermo-responsive biopolymers in drug delivery systems. One of the major applications of such thermos-responsive biopolymers is on textile-based transdermal therapy where the formulation, mechanical, and drug release properties and the cytotoxicity of thermo-responsive hydrogel in drug delivery systems of traditional Chinese medicine have been fully reviewed. Textile-based transdermal therapy, a non-invasive method to treat skin-related disease, can overcome the poor bioavailability of drugs from conventional non-invasive administration. This study also discusses the future prospects of stimuli-responsive hydrogels made of thermo-responsive biopolymers for non-invasive treatment of skin-related disease via textile-based transdermal therapy.

Preparation and osteogenic properties of nanocomposite hydrogel beads loaded with nanometric bioactive glass particles

Bone reconstruction in the oral and maxillofacial region presents particular challenges related to the development of biomaterials with osteoinductive properties and suitable physical characteristics for their surgical use in irregular bony defects. In this work, the preparation and bioactivity of chitosan–gelatin (ChG) hydrogel beads loaded with either bioactive glass nanoparticles (nBG) or mesoporous bioactive glass nanospheres (nMBG) were studied. In vitro testing of the bionanocomposite beads was carried out in simulated body fluid, and through viability and osteogenic differentiation assays using dental pulp stem cells (DPSCs). In vivo bone regenerative properties of the biomaterials were assessed using a rat femoral defect model and compared with a traditional maxillary allograft (Puros®). ChG hydrogel beads containing homogeneously distributed BG nanoparticles promoted rapid bone—like apatite mineralization and induced the osteogenic differentiation of DPSCs in vitro. The bionanocomposite beads loaded with either nBG or nMBG also produced a greater bone tissue formation in vivo as compared to Puros® after 8 weeks of implantation. The osteoinductivity capacity of the bionanocomposite hydrogel beads coupled with their physical properties make them promissory for the reconstruction of irregular and less accessible maxillary bone defects.

Developing a Glyoxal-Crosslinked Chitosan/Gelatin Hydrogel for Sustained Release of Human Platelet Lysate to Promote Tissue Regeneration.

The clinical application of human platelet lysate (HPL) holds promise for tissue regeneration, and the development of an efficient vehicle for its delivery is desired. Chitosan-based hydrogels are potential candidates, but they often exhibit weak mechanical properties. In this study, a chitosan/gelatin (CS-GE) hydrogel crosslinked by glyoxal was fabricated for sustained release of HPL. The influence of HPL on Hs68 fibroblast and human umbilical vein endothelial cell (HUVEC) culture was evaluated, and we found that supplementing 5% HPL in the medium could significantly improve cell proliferation relative to supplementing 10% fetal bovine serum (FBS). Moreover, HPL accelerated the in vitro wound closure of Hs68 cells and facilitated the tube formation of HUVECs. Subsequently, we fabricated CS-GE hydrogels crosslinked with different concentrations of glyoxal, and the release pattern of FITC-dextrans (4, 40 and 500 kDa) from the hydrogels was assessed. After an ideal glyoxal concentration was determined, we further characterized the crosslinked CS-GE hydrogels encapsulated with different amounts of HPL. The HPL-incorporated hydrogel was shown to significantly promote the proliferation of Hs68 cells and the migration of HUVECs. Moreover, the release pattern of transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB) from hydrogel was examined in vitro, demonstrating a sustained release profile of the growth factors. Finally, the chick chorioallantoic membrane assay revealed that HPL encapsulation in the hydrogel significantly stimulated angiogenesis in ovo. These results demonstrate the great potential of the crosslinked CS-GE hydrogel to serve as an effective delivery system for HPL to promote tissue regeneration.

Chitosan/Gelatin/Silver Nanoparticles Composites Films for Biodegradable Food Packaging Applications.

The food packaging industry explores economically viable, environmentally benign, and non-toxic packaging materials. Biopolymers, including chitosan (CH) and gelatin (GE), are considered a leading replacement for plastic packaging materials, with preferred packaging functionality and biodegradability. CH, GE, and different proportions of silver nanoparticles (AgNPs) are used to prepare novel packaging materials using a simple solution casting method. The functional and morphological characterization of the prepared films was carried out by using Fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, and scanning electron microscopy (SEM). The mechanical strength, solubility, water vapor transmission rate, swelling behavior, moisture retention capability, and biodegradability of composite films were evaluated. The addition of AgNPs to the polymer blend matrix improves the physicochemical and biological functioning of the matrix. Due to the cross-linking motion of AgNPs, it is found that the swelling degree, moisture retention capability, and water vapor transmission rate slightly decrease. The tensile strength of pure CH–GE films was 24.4 ± 0.03, and it increased to 25.8 ± 0.05 MPa upon the addition of 0.0075% of AgNPs. The real-time application of the films was tested by evaluating the shelf-life existence of carrot pieces covered with the composite films. The composite film containing AgNPs becomes effective in lowering bacterial contamination while comparing the plastic polyethylene films. In principle, the synthesized composite films possessed all the ideal characteristics of packaging material and were considered biodegradable and biocompatible food packaging material and an alternate option for petroleum-based plastics.

Three-Dimensional-Printable Thermo/Photo-Cross-Linked Methacrylated Chitosan-Gelatin Hydrogel Composites for Tissue Engineering.

Biomimetic constructs imitating the functions, structures, and compositions of normal tissues are of great importance for tissue repair and regeneration. Three-dimensional (3D) printing is an innovative method to construct intricate biomimetic 3D tissue engineering scaffolds with spatiotemporal deposition of materials to control the intrinsic architectural organization and functional performance of the scaffold. However, due to the lack of bioinks with suitable printability, high structural integrity, and biological compatibility, producing constructs that mimic the anisotropic 3D extracellular environments remains a challenge. Here, we present a printable hydrogel ink based on methylacrylate-modified chitosan (ChMA) and gelatin (GelMA) embedding nanohydroxyapatite (nano-Hap). This polymer composite is first physically cross-linked by thermal gelation for postprinting structural stability, followed by covalent photo-cross-linking of ChMA and GelMA to form a long-term stable structure. The rheological behavior of the hydrogels and the mechanical strengths of the printed constructs are tuned by adjusting the content of GelMA, which in turn enhances the shape retention after printing and enables the precise deposition of multilayered 3D scaffolds. Moreover, the formulated biomaterial inks exhibit biological characteristics that effectively support the spreading and proliferation of stem cells seeded on the scaffolds after 7 days of in vitro culture. Adding Hap has minor influences on the mechanical rigidity and cytocompatibility of the hydrogels compared with the group free of Hap. Together, the printable biomaterial inks with shear thinning and good structural integrity, along with biological cues, are promising for tissue engineering application.

How the temperature and salt content of food simulant affect the release of tyrosol or phenolic acids from bioactive films?

Active films made of chitosan and fish gelatin blends containing 5% (w/wt of polymers) of tyrosol, ferulic acid or caffeic acid were prepared by the casting method. The kinetic of release was assessed in water or in 1% (w/v) NaCl solution, at three temperatures (4, 25 and 32°C). Partition (Kf/S) and the effective diffusivity (D) was modelled which allowed to characterize the release mechanism. Tyrosol has a faster release at a higher concentration than the other antioxidants, because of its structure and a lower level of intermolecular interactions with the biopolymer matrix. There is less effect of temperature and of the salt content on the release of tyrosol contrarily to the phenolic acids. The NaCl solution (food simulant) induced conformational changes in the biopolymer network due to the modifications of the interactions between the gelatin, chitosan and antioxidants, inducing a less strengthen network and a faster release.

Probiotic bacteria cell surface-associated protein mineralized hydroxyapatite incorporated in porous scaffold: In vitro evaluation for bone cell growth and differentiation

There is a high demand for synthesis of biocompatible hydroxyapatite nanoparticle (HANP), which is a key component in bone tissue engineering scaffolds. The present study describes a facile route of HANP synthesis through mineralization of the cell surface-associated protein (CSP) from the human probiotic lactic acid bacteria (LAB) Lactobacillus rhamnosus GG. CSP extract from the LAB (consisting of ~66 kDa, ~47 kDa, ~40 kDa and ~25 kDa protein) was mineralized to yield spindle-shaped HANPs having an average particle length of 371 nm as evidenced in FETEM analysis. CSP-mineralized HANPs (CSP-HANPs) were characterized by FTIR and BET analysis, while XRD and SAED analysis indicated their crystalline nature. Mechanistic studies suggested the key role of ~25 kDa CSP (F4SP) in mineralization. In contrast to CSP-HANPs, F4SP-mineralized crystalline HA was plate-shaped having an average length of 1.68 μm and breadth of 0.95 μm. HANP mineralization at the whole-cell (WC) level resulted in clusters of aggregated HANPs (WC-HANPs) adhering onto L. rhamnosus GG cells as evident in FETEM, FESEM and AFM analysis. FETEM analysis revealed that the desorbed WC-HANPs recovered by cell lysis were needle-shaped, with a particle size distribution of 70–110 nm. Given that CSP-HANPs were non-toxic to cultured HEK 293 cells and osteoblast-like MG-63 cells, chitosan-gelatin (CG) scaffold incorporated with 15% w/v CSP-HANP (H-CG) was generated and tested for bone cell growth. H-CG exhibited a favorable pore size distribution (160–230 μm), overall porosity (~84%) and biodegradation profile. H-CG scaffold was conducive to osteogenesis and rendered enhanced proliferation, alkaline phosphatase (ALP) activity, calcium mineralization and heightened marker gene expression (ALP, Col I, Runx2 and OCN) in seeded MG-63 cells. CSP sourced from a safe probiotic LAB is thus a viable and effective mineralization template for synthesis of biocompatible HANPs that can be leveraged for bone tissue engineering applications.

Functional Hydrophilic Membrane for Oil-Water Separation Based on Modified Bio-Based Chitosan-Gelatin.

In this study, we fabricated a modified biomaterial based on chitosan and gelatin, which is an intrinsic hydrophilic membrane for oil–water separation to clean water contamination by oil. Modification of the membrane with a non-toxic natural crosslinker, genipin, significantly enhanced the stability of the biopolymer membrane in a water-based medium towards an eco-friendly environment. The effects of various compositions of genipin-crosslinked chitosan–gelatin membrane on the rheological properties, thermal stability, and morphological structure of the membrane were investigated using a dynamic rotational rheometer, thermogravimetry analysis, and chemical composition by attenuated total reflectance spectroscopy (ATR). Modified chitosan–gelatin membrane showed completely miscible blends, as determined by field-emission scanning electron microscopy, differential scanning calorimetry, and ATR. Morphological results showed membrane with establish microstructure to further experiment as filtration product. The membranes were successfully tested for their oil–water separation efficiencies. The membrane proved to be selective and effective in separating water from an oil–water mixture. The optimum results achieved a stable microporous structure of the membrane (microfiltration) and a separation efficiency of above 98%. The membrane showed a high permeation flux, generated as high as 698 and 420 L m−2 h−1 for cooking and crude oils, respectively. Owing to its outstanding recyclability and anti-fouling performance, the membrane can be washed away easily, ensuring the reusability of the prepared membrane.

Physical and self–crosslinking mechanism and characterization of chitosan-gelatin-oxidized guar gum hydrogel

The secret of hydrogel formation lies in the intricate chemistry between the constituents and its effective crosslinking. Hydrogels made up of natural polymers have gained immense popularity on account of their biodegradability and biocompatibility. In this work, chitosan–gelatin–oxidized guar gum hydrogel was fabricated with the help of physical and self-crosslinking. Initially, guar gum was exposed to periodate oxidation, and the resultant oxidized guar gum witnessed the transformation of diols into dicarboxylic acids, as validated by Fourier transform infrared spectroscopy. Furthermore, the hydrogel chemistry was decoded to reveal that the carbonyl functional group of oxidized guar gum participated in self-crosslinking associations with gelatin. Moreover, it was found that β-glycerophosphate was responsible for physical crosslinking and sodium bicarbonate decreased the charge density by deprotonation and facilitated hydrogen bonding. Notably, different levels of periodate oxidation were carried out, and the corresponding hydrogels were characterized by several ways to draw a comparative analysis between the level of oxidized guar gum and the essential characteristics of the hydrogels, with a major emphasis on hydrogel chemistry.

Physical properties and bioactivities of chitosan/gelatin-based films loaded with tannic acid and its application on the preservation of fresh-cut apples

The aim of this research is to develop composite (CG-TA) films by using chitosan (CS)/gelatin (GL)/tannic acid (TA), for fresh-cut apples preservation. TA was used as the crossing-linking agent to improve the mechanical and barrier properties, and as the active substance to improve the anti-ultraviolet and antioxidant abilities of the chitosan/gelatin (CG) film. With the incorporation of TA from 0 to 1 wt%, the tensile strength of the CG film was increased while the water vapor and oxygen permeability of the film were decreased. The CG-TA films containing more than 0.5 wt% of TA could effectively block most of UV light. The DPPH radical scavenging assay significant increased to 89.3% when the concentration of TA reached 2 wt%. Finally, CG and CG-TA films, as an active packaging material, were used to preserve the cold-stored fresh-cut apples. Compared with CG film, the CG-TA films obtained better performance on decreasing weight loss, delaying browning degree, inhibiting the lipid oxidase activity and decreasing the malondialdehyde content during 10 d of storage under 4 °C. Therefore, CG-TA films were expected to be a new active packaging material for preserving fresh-cut apples.

Isolation of Diarrheagenic Escherichia coli and their Specific Phages from Rabbits

This study designed to isolation virulence E. coli, specific phages and identify in rabbits biochemically, serologically, detect virulence genes using PCR and susceptibility to antimicrobial range. For propose fifty-fecal-swab samples collected from diarrheic and freshly-dead-young-rabbits were presented to bacteriological examination. Data showed twenty-seven samples (54%) gave positive results of Escherichia coli. Data in-vitro Pathogenicity-test using Congo-red(CR) binding assay showed eight E. coli isolates (29.63%) were Congo-red positive. Antimicrobial susceptibility to several antibiotics was studied. E. coli isolates showed different susceptibility degrees to antibiotics, and isolates 3,4 and 8 categorized as multidrug resistant isolates. Three selected E. coli isolates were serologically identified classified as O169, O125 and O158 serotypes for isolates 4,8,3 respectively. Conventional polymerase chain reaction for detection eaeA and Stx1 virulence genes revealed E. coli serotypes O158 expressed eaeA gene, but others, O169 and O125 don't expressed. While, none serotypes expressed Stx1 gene. Phages may be used effectively to control of pathogenic E. coli, colonizing farm rabbit's intestines. However, harsh acidic-conditions and digestive enzymes activities influence phage infectivity, and decrease efficiency in application-trails. Natural-defensive-barrier development was being suitable for oral administration to farm poultry presented acid-stability. Encapsulated pahge beads in gelatin chitosan -matrix showed partial phage titer reductions. Phage beads titers were constant for storage in water, but complete release achieved after 6hr in simulated intestinal solution at 37°C. Finding multidrug resistant enterohaemorrhagic, E. coli serotypes created severe health hazard for rabbits and contact human. Encapsulated phages beads are promising and cost-effective method for bacteriophage targeting intestinal bacteria of farm-rabbits.

Novel chitosan/gelatin/oxidized cellulose sponges as absorbable hemostatic agents

Chitosan/gelatin (CG) composite sponges containing oxidized cellulose fibers (OF) crosslinked with tannic acid were fabricated by freeze-drying as hemostatic agents. The cellulose fibers were oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Fourier transform infrared spectroscopy proved the formation of carboxyl groups on cellulose fibers. Addition of OF increased the swelling ratio of CG sponges. The amount of bleeding was measured after 10 s on hepatic trauma in a rat model. To assess the in vivo bio-absorbability of the samples, the sponges were implanted in the liver for 21 days and the volume of the repaired tissue was measured from histopathological analysis. The biocomposite sponge fabricated by addition of 30% OF suspension into CG solution showed the lowest amount of bleeding and the highest bio-absorbability after 21 days. The findings of this study indicate that the addition of OF into CG increased the clotting capability as well as the bio-absorbability of the biocomposite sponges.

Effect of orange (Citrus sinensis L.) peel essential oil on characteristics of blend films based on chitosan and fish skin gelatin

A novel composite packaging film based on fish (Cynoglossus semilaevis) skin gelatin (FSG) and water soluble chitosan (CH) incorporated with the concentrations(0.25,0.5,1.0%, v/v) of orange peel essential oils (OPEO) were prepared and characterized. OPEO incorporation dose-dependently lowered the values of tensile strength, elastic modulus, water solubility, moisture content and water vapor permeability. Nevertheless, OPEO raised elongation at break, contact angle. Fourier transform infrared spectroscopy analyses spectra pattern suggested the structural interaction between OPEO and FSG/CH molecules in the films. The noticeable decline in values of L* and a* with coincidental enhancement in values of b*, △E and Opacity were observed when OEPO concentrations increased. Films containing OPEO showed slightly lower degradation temperature and weight loss compared with the control film. Moreover, inclusion of OPEO promoted the inhibitory activity of the bio-composite films against free radicals (DPPH and ABTS) and the tested microorganisms (Staphylococcus aureus and Escherichia coli). Overall, it can be suggested that FSG/CH based active blend films incorporated with OPEO could offer potential packaging material to maintain food quality.

Chitosan–gelatin enhanced antibacterial and biological properties of PLA and PGA braided threads for juvenile pseudomyopia treatment

Polylactic acid (PLA) and polyglycolide acid (PGA) have been the most widely used biomedical materials in the acupoint catgut-embedding therapy (ACET) fields. However, a lack of antibacterial and biological properties is a definite obstacle that hinders its further application in juvenile pseudomyopia treatment. Here, four different kinds of PLA and PGA threads were fabricated, and were then modified using chitosan–gelatin coating method. Afterwards, PLA and PGA braided threads were fully characterized with respect to structure, mechanical and biological properties. The results showed that the surface roughness of PLA and PGA had been greatly improved; FT-IR analysis proved the existence of chitosan and gelatin molecules, the modified PLA (M-PLA-a = 87.1° ± 1.5°, M-PLA-b = 83.5° ± 1.4°) had smaller contact angle values than that of non-modified PLA (PLA-a = 108.6° ± 2.6°, PLA-b = 116.2° ± 3.1°), and that of the modified PGA (M-PGA-a = 79.3° ± 3.2°, M-PGA-b = 73.8° ± 1.8°) was smaller compared with that of the non-modified PGA (PGA-a = 98.2° ± 1.7°, PGA-b = 83.5° ± 1.4°). Based on the mechanical testing results, the tensile property and flexibility of samples increased slightly, and their swelling behavior also increased correspondingly. All the prepared samples exhibited non-toxicity with cell viability of more than 75%, and samples M-PGA-b presented the largest cell attachment ratios. In sum, this work exhibited great potential in the ACET application for juvenile pseudomyopia treatment.

Gelatin/Chitosan Bilayer Patches Loaded with Cortex Phellodendron amurense/Centella asiatica Extracts for Anti-Acne Application.

Acne is a chronic inflammatory skin disease that often occurs with anaerobic Propionibacterium acnes (P. acnes). Anti-acne patches, made of hydrocolloid or hydrogel, have become a popular way of topical treatment. The outer water-impermeable layer of commercial patches might create hypoxic conditions and promote P. acnes growth. In this study, gelatin/chitosan (GC) bilayer patches were prepared at different temperatures that included room temperature (RT), −20 °C/RT, and −80 °C/RT. The most promising GC bilayer patch (−80 °C /RT) contained a dense upper layer for protection from bacteria and infection and a porous lower layer for absorbing pus and fluids from pimples. The anti-acne bilayer patch was loaded with Cortex Phellodendri amurensis (PA) and Centella asiatica (CA) extracts. PA extract could inhibit the growth of P. acnes and CA extract was reported to improve wound healing and reduce scar formation. Moreover, the water retention rate, weight loss rate, antibacterial activity, and in vitro cytotoxicity of the patches were investigated. The porous structure of the patches promoted water retention and contributed to absorbing the exudate when used on open acne wounds. The GC bilayer patches loaded with PA/CA extracts were demonstrated to inhibit the growth of P. acnes, and accelerate the skin fibroblast cell viability. Based on their activities and characteristics, the GC bilayer patches with PA/CA extract prepared at −80 °C/RT obtain the potential for the application of acne spot treatment.

Biological functionalization of poly (lactic-co-glycolic acid) with ammonia and chitosan–gelatin combined treatment for acupoint catgut-embedding therapy

Polylactic-co-glycolic acid (PLGA) has attracted extensive attention in acupoint catgut embedding therapy (ACET). However, developing biological functionalization for ACET materials remains challenging to due to its poor surface properties. In this work, PLGA was first treated with ammonia solution, and chitosan–gelatin coating was then introduced onto the surface of PLGA braided thread to achieve biological functionalization. Characteristics such as structural, mechanical, and in vitro properties were then fully evaluated. The results showed that modified samples showed more surface roughness than non-modified ones, and weight and diameter changes in samples increased after coating treatment, together with surface hydrophilicity; mechanical properties such as tensile property and bending stiffness of samples were greatly enhanced. Non-coated samples exhibited no antibacterial properties, while that of coated samples showed different antibacterial properties against Escherichia coli and Staphylococcus aureus. No samples showed toxicity, with more than 75% cells viable. In sum, the strategy of surface-modified PLGA using a combined ammonia and chitosan–gelatin treatment showed great potential in the application of ACET.

Poly(lactic-co-glycolic acid)-Chitosan-Gelatin Composite Nanomaterials for the Treatment of Diabetic Foot Ulcer Wound Infection.

In this experiment, a solid carrier was prepared with PLGA, gelatin, and chitosan as the main raw materials, so that BMSCs could exert their repairing effect directly in the ulcer area under the stimulation of Klotho protein. We chose to use electrospun PLGA as the main technical means to provide suitable adhesion growth environment for BMSCs by preparing PLGA nanofibers. At the same time, PLGA nanofibers are also a controlled release material, so that Klotho protein can remain active, thereby achieving the purpose of stimulating BMSCs for a long time. Through the nano-scale porous structure provided on the surface of the PLGA film, BMSCs can adhere well to the surface of the material and continuously receive stimulation from the inner Klotho protein. We applied this composite to mice with diabetic ulcers, and verified the effects of Klotho protein and BMSCs on DFU healing in five groups of mice. From the results, the Klotho+BMSCs group achieved the best healing effect, followed by the Klotho group alone, while the other three groups had no significant difference in healing effects. It is proved that both Klotho and BMSCs can help the healing of diabetic ulcers, but BMSCs alone cannot survive in harsh environments, and it is difficult to play a normal repair role. The purpose of this study was to investigate the effect of Klotho protein on BMSCs and ECs under high glucose conditions, and to find a suitable carrier for planting BMSCs on it. At the same time, the material also has a certain sustained release function. We have concluded that Klotho protein can promote the proliferation and migration of BMSCs and ECs under high glucose conditions. When combined with electrospinning technology to prepare a protein that can release Klotho, it also provides a microstructure suitable for BMSCs adhesion, thereby ensuring that BMSCs can successfully survive. In the end, we artificial Klotho protein can promote angiogenesis in diabetic ulcer areas by protecting BMSCs and ECs, thereby promoting healing of ulcer areas.