Injectable hydrogels based on oxidized alginate-gelatin reinforced by carbon nitride quantum dots for tissue engineering

Fluorescent probe for imaging N2H4 in plants, food, and living cells and for quantitative detection of N2H4 in soil and water using a smartphone

Hydrazine is volatile and highly toxic, causing severe harm to water, soil, air, and organisms. Therefore, real-time detection and long-term monitoring of hydrazine are crucial for environmental protection and human health. Herein, an "OFF-ON" fluorescent probe 5-((10-ethyl-2-methoxy-10 H-phenothiazin-3-yl)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (MPD) for hydrazine detection through a nucleophilic addition reaction was developed. MPD could exclusively identify hydrazine through colorimetric and fluorescent dual-channel responses within 30 s, which also demonstrated high sensitivity (detection limit, 12 nM) and a wide pH range (6 -12). The sensing mechanism of MPD was confirmed using theoretical calculations, where fluorescence was emitted following the recognition of hydrazine because of the disappearance of the photoinduced electron transfer (PET) process. Using a smartphone, MPD enabled the quantitative detection of hydrazine in real water samples and sandy soil. Notably, in the process of detecting hydrazine in actual water samples, the establishment of analytical methods and the completion of rapid quantitative detection only required a smartphone and built-in apps. Additionally, we showed that MPD could recognize hydrazine in various environmental samples, including plants, food, hydrazine vapors, and cells. We believe that the fluorescent probe MPD developed in this study and the established smartphone visualization platform will provide a convenient and effective tool for detecting hydrazine in environmental monitoring, food safety assessment, biological system safety, and other fields.

Oxidized ionic polysaccharide hydrogels: Review on derived scaffolds characteristics and tissue engineering applications

Polysaccharide-based hydrogels have gained prominence due to their non-toxicity, biocompatibility, and structural adaptability for constructing tissue engineering scaffolds. Polysaccharide crosslinking is necessary for hydrogel stability in vivo. The periodate oxidation enables the modification of native polysaccharide characteristics for wound healing and tissue engineering applications. It produces dialdehydes, which are used to crosslink biocompatible amine-containing macromolecules such as chitosan, gelatin, adipic acid dihydrazide, silk fibroin, and peptides via imine/hydrazone linkages. Crosslinked oxidized ionic polysaccharide hydrogels have been studied for wound healing, cardiac and liver tissue engineering, bone, cartilage, corneal tissue regeneration, abdominal wall repair, nucleus pulposus regeneration, and osteoarthritis. Several modified hydrogel systems have been synthesized using antibiotics and inorganic substances to improve porosity, mechanical and viscoelastic properties, desired swelling propensity, and antibacterial efficacy. Thus, the injectable hydrogels provide a host-tissue-mimetic environment with high cell adhesion and viability, making them appropriate for scarless wound healing and tissue engineering applications. This review describes the oxidation procedure for alginate, hyaluronic acid, gellan gum, pectin, xanthan gum and chitosan, as well as the characteristics of the resulting materials. Furthermore, a critical review of scientific advances in wound healing and tissue engineering applications has been provided.

A novel carboxylesterase 2-targeted fluorescent probe with cholic acid as a recognition group for early diagnosis of drug- and environment-related liver diseases

Due to the detrimental effects of various harmful substances-such as carcinogens, drug toxicity, and environmental pollutants-on the liver, which can trigger or exacerbate conditions like hepatocellular carcinoma (HCC), drug-induced liver injury (DILI), and non-alcoholic fatty liver disease (NAFLD), accurate detection and monitoring of these diseases are crucial for effective treatment. Carboxylesterase 2 (CES2) is primarily found in the liver and, as a potential biomarker, its accurate detection can enhance the early diagnosis and treatment efficacy of liver diseases. Traditional fluorescence probes for CES2 detection suffer from non-specific recognition groups, leading to poor targeting specificity. To address this limitation, we propose a novel CES2-responsive fluorescent probe utilizing cholic acid (CA) as a recognition group. The probe, LAN-CA, was synthesized by esterifying CA with a near-infrared fluorophore, LAN-OH. This novel fluorescent probe leverages the unique affinity of CA for hepatocytes, ensuring that LAN-CA remains and accumulates specifically within the hepatoenteric circulation. In vitro experiments showed that the probe exhibits superior optical performance compared to traditional benzoate-based probe (LAN-PH), with a detection limit of 0.015 μg/mL. Examination of 56 common biological interferents demonstrated that using CA as a recognition group offers high selectivity. Cell experiments confirmed that LAN-CA is an effective tool for monitoring endogenous CES2 in live cells. Comprehensive evaluations of fluorescence imaging in various mouse models of liver diseases, such as HCC, DILI, and NAFLD, demonstrated that LAN-CA provides exceptional imaging accuracy and therapeutic monitoring capabilities. In conclusion, this probe not only can be a promising tool for accurate liver disease diagnosis, but also can provide valuable insights into treatment efficacy.

Conductive, injectable, and self-healing collagen-hyaluronic acid hydrogels loaded with bacterial cellulose and gold nanoparticles for heart tissue engineering

The increasing demand for advanced biomaterials in nerve tissue engineering presents numerous challenges due to the complexity of nerve tissues and the need for materials that can accurately replicate their intricate structure and function. In response, this study introduces a novel injectable hydrogel that is thermosensitive, self-healing, and conductive, offering promising potential for nerve tissue engineering applications. The hydrogel is based on collagen and hyaluronic acid functionalized with 3-aminopropyl-triethoxysilane (APTES)-grafted oxidized bacterial cellulose and gold nanoparticles (~50 nm). Rheological analysis reveals a substantial enhancement in the elastic modulus of the collagen-hyaluronic acid matrix with the incorporation of bacterial cellulose/gold nanoparticles, improving by an order of magnitude at 1 % strain. This improvement comes with a slight decrease in gelation temperature, from 36 °C to 32 °C. Besides thermo-sensitivity, the nanocomposite hydrogel exhibits a remarkable self-sealing response (about 80 % effectiveness) due to reversible physical crosslinking. Electrical spatial resistance measurements on human embryonic stem cell-derived cardiomyocytes-loaded hydrogels yield a value of ~0.1 S/m, which is suitable for electrical stimulation. In vitro extracellular field potential measurements also affirm the hydrogel's potential as an injectable scaffold for heart tissue engineering, i.e., the electrically stimulated human stem cells exhibit 47 beats per minute with a cell discharge (depletion) of 5.47 μv. A rapid gel formation in the physiological temperature (about 2 min) and high H9C2 cytotoxicity (viability of >90 % after 72 h incubation) is attainable. The developed collagen-based nanocomposite hydrogel offers an injectable, thermosensitive, and self-healing biomaterial platform for nerve or myocardium regeneration.

Novel cross-linkable fluorescent probe with oriented antibody to enhance lateral immunoassay strip for the detection of acetamiprid

Time-resolved fluorescent lateral immunoassay strip (TRFLIS) is a reliable and rapid method for detecting acetamiprid. However, its sensitivity is often affected by the structural patterns and stability of the fluorescent probe. Researchers have shown significant interests in using goat anti-mouse IgG (GaMIgG) which is indirectly bound to time-resolved fluorescent microsphere (TRFM) and antibody. This allowed for oriented modification of the antibody. However, the stability of fluorescent probe in this binding mode remained unexplored. Herein, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was innovatively used as a cross-linking agent to enhance the binding of antibody to GaMIgG, which improved the stability of the fluorescent probe. Under optimal working conditions, this strategy exhibited a wide linear response range of 5-700 ng/mL. Its limit of detection (LOD) was 0.62 ng/mL, the visual LOD was 5 ng/mL, and the limit of quantification (LOQ) of 2.06 ng/mL. Additionally, under tomato matrix, leek matrix and Chinese cabbage matrix, the linear response ranges were 5-400, 5-300, and 5-700 ng/mL, with LODs of 0.16, 0.60, and 0.41 ng/mL, with LOQs of 0.53, 2.01 and 1.37 ng/mL, respectively. In conclusion, this strategy effectively reduced the dosage of acetamiprid antibody compared with TRFM directly linking acetamiprid antibody, and greatly increased the sensitivity of TRFLIS. Meanwhile, it demonstrated outstanding specificity and accuracy in acetamiprid detection and had been successfully applied to vegetable samples. This method enables rapid and accurate detection of large-volume samples by combining qualitative and quantitative methods. As such, it has great potential in the development of low-cost and high-performance immunochromatographic platforms.

Microneedles-mediated calcium-ion-modulated nanoamplifier for potentiating photodynamic therapy via specific-tuning assembly and tumor microenvironment remold

Off-targeting toxicity and immunosuppressive tumor microenvironment still restrict the therapeutic requirement of photodynamic therapy (PDT). The development of metal ion-coordination-based nanoparticles (NPs) for cancer therapy has advantages, such as precious nanostructure and potent therapeutic effect as well as great safety. In this study, we prepared calcium ions (Ca2+)-coordination photosensitizer NPs, based on Ca2+-pyrochloric acid (PPA)-coordination as the new photosensitive nanoamplifiers, and microneedles (MNs) as the personalized apparatus, and investigated the nanoamplifiers for treating the melanoma via transdermal administration. This nanoamplifiers was synthesized via a simple coordination of Ca2+ and PPA with the addition of bovine serum albumin (BSA), and further fabricated into MNs (nanoamplifiers@MNs). Following inserted into the tumor, the released nanoamplifiers from the tips and back layer exhibited great photodynamic activity under irradiation, inducing cancer cell death. Meanwhile, Ca2+ acted as the second messenger, promoting M1 polarization of macrophages and maturation of dendritic cells (DCs), thereby enhancing the immune activation effect in the tumor microenvironment. As a result, such nanoamplifiers effectively achieved significant efficacy against malignant melanoma tumors by synergistically tumor killing and potent anti-tumor immune activation without obviously side effect. This work demonstrated the potential of MNs-mediated metal ion-coordination-based nanoamplifier as a novel photodynamic therapeutic platform for the efficient and safe treatment of cancer.

A study on the performance, structure, composition, and release behavior changes of polybutylene adipate terephthalic acid (PBAT) film during food contact

Polybutylene adipate terephthalic acid (PBAT) is an emerging biodegradable material in food packaging. However, concerns have been raised regarding the potential hazards it could pose to food safety. In this study, the changes of PBAT films during food contact and the release of small molecules were inestigated by a multiscale approach. On a macro-scale, the surface roughness of the films increased with the reduction in the concentration of food simulants and the increase in contact temperatures, especially after immersion in acidic food environments. On a micro-scale, the crystallinity (Xc) and degradation indexes (DI) of the films increased by 5.7-61.2% and 7.8-48.6%, respectively, which led to a decrease in thermal stability. On a scale approaching the molecular level, 2,4-di-tert-butylphenol (2,4-DTBP) was detected by gas chromatography-mass spectrometry (GC-MS/MS) with the highest migration content, and the release behavior of 2,4-DTBP was further investigated by migration kinetics. In addition, terephthalic acid (TPA), a hydrolysis product of PBAT, was detected in acidic food environments by liquid chromatography-mass spectrometry (LC-MS/MS). The results of this study could provide practical guidance and assistance to promote sustainable development in the field of food packaging.

Nanocarrier mediated entinostat and oxaliplatin combination therapy displayed enhanced efficacy against pancreatic cancer

Pancreatic cancer is the third leading cause of cancer-related death in the United States, with a 5-year survival rate of only 12%. The poor prognosis of pancreatic cancer is primarily attributed to the lack of early detection, the aggressiveness of the disease, and its resistance to conventional chemotherapeutics. The use of combination chemotherapy targeting different key pathways has emerged as a potential strategy to minimize drug resistance while improving therapeutic outcomes. Here, we evaluated a novel approach to treating pancreatic cancer using entinostat (ENT), a selective class I and IV HDAC inhibitor, and oxaliplatin (OXP) administered at considerably lower dosages. Combination therapy exhibited strong synergistic interaction against human (PANC-1) and murine (KPC) pancreatic cancer cells. As expected, ENT treatment enhanced acetylated histone H3 and H4 expression in treated cells, which was even augmented in the presence of OXP. Similarly, cells treated with a combination therapy showed higher expression of cleaved caspase 3 and increased apoptosis compared to monotherapy. To further improve the efficacy of the combination treatment, we encapsulated OXP and ENT into bovine serum albumin and poly(lactic-co-glycolic) acid nanoparticles. Both nanocarriers showed suitable physicochemical properties with respect to size, charge, polydispersity index, and loading. Besides, the combination of OXP and ENT nanoparticles showed similar or even better synergistic effects compared to free drugs during in vitro cytotoxicity and colony formation assays towards pancreatic cancer cells.

Current trend on preparation, characterization and biomedical applications of natural polysaccharide-based nanomaterial reinforcement hydrogels: A review

The tunable properties of hydrogels have led to their widespread use in various biomedical applications such as wound treatment, drug delivery, contact lenses, tissue engineering and 3D bioprinting. Among these applications, natural polysaccharide-based hydrogels, which are fabricated from materials like agarose, alginate, chitosan, hyaluronic acid, cellulose, pectin and chondroitin sulfate, stand out as preferred choices due to their biocompatibility and advantageous fabrication characteristics. Despite the inherent biocompatibility, polysaccharide-based hydrogels on their own tend to be weak in physiochemical and mechanical properties. Therefore, further reinforcement in the hydrogel is necessary to enhance its suitability for specific applications, ensuring optimal performance in diverse settings. Integrating nanomaterials into hydrogels has proven effective in improving the overall network and performance of the hydrogel. This approach also addresses the limitations associated with pure hydrogels. Next, an overview of recent trends in the fabrication and applications of hydrogels was presented. The characterization of hydrogels was further discussed, focusing specifically on the reinforcement achieved with various hydrogel materials used so far. Finally, a few challenges associated with hydrogels by using polysaccharide-based nanomaterial were also presented.

Roles and mechanisms of copper homeostasis and cuproptosis in osteoarticular diseases

Copper is an essential trace element in the human body that is extensively distributed throughout various tissues. The appropriate level of copper is crucial to maintaining the life activities of the human body, and the excess and deficiency of copper can lead to various diseases. The copper levels in the human body are regulated by copper homeostasis, which maintains appropriate levels of copper in tissues and cells by controlling its absorption, transport, and storage. Cuproptosis is a distinct form of cell death induced by the excessive accumulation of intracellular copper. Copper homeostasis and cuproptosis has recently elicited increased attention in the realm of human health. Cuproptosis has emerged as a promising avenue for cancer therapy. Studies concerning osteoarticular diseases have elucidated the intricate interplay among copper homeostasis, cuproptosis, and the onset of osteoarticular diseases. Copper dysregulation and cuproptosis cause abnormal bone and cartilage metabolism, affecting related cells. This phenomenon assumes a critical role in the pathophysiological processes underpinning various osteoarticular diseases, with implications for inflammatory and immune responses. While early Cu-modulating agents have shown promise in clinical settings, additional research and advancements are warranted to enhance their efficacy. In this review, we summarize the effects and potential mechanisms of copper homeostasis and cuproptosis on bone and cartilage, as well as their regulatory roles in the pathological mechanism of osteoarticular diseases (e.g., osteosarcoma (OS), osteoarthritis (OA), and rheumatoid arthritis (RA)). We also discuss the clinical-application prospects of copper-targeting strategy, which may provide new ideas for the diagnosis and treatment of osteoarticular diseases.

Recent advances in composite hydrogels: synthesis, classification, and application in the treatment of bone defects

Bone defects are often difficult to treat due to their complexity and specificity, and therefore pose a serious threat to human life and health. Currently, the clinical treatment of bone defects is mainly surgical. However, this treatment is often more harmful to patients and there is a potential risk of rejection and infection. Hydrogels have a unique three-dimensional structure that can accommodate a variety of materials, including particles, polymers and small molecules, making them ideal for treating bone defects. Therefore, emerging composite hydrogels are considered one of the most promising candidates for the treatment of bone defects. This review describes the use of different types of composite hydrogel in the treatment of bone defects. We present the basic concepts of hydrogels, different preparation techniques (including chemical and physical crosslinking), and the clinical requirements for hydrogels used to treat bone defects. In addition, a review of numerous promising designs of different types of hydrogel doped with different materials (e.g., nanoparticles, polymers, carbon materials, drugs, and active factors) is also highlighted. Finally, the current challenges and prospects of composite hydrogels for the treatment of bone defects are presented. This review will stimulate research efforts in this field and promote the application of new methods and innovative ideas in the clinical field of composite hydrogels.

The three-dimensional culture of L929 and C2C12 cells based on SPI-SA interpenetrating network hydrogel scaffold with excellent mechanical properties

Cell-cultured meat, which is obtained by adsorbing cells on the three-dimensional scaffold, is considered a potential solution to animal welfare issues. Edible and safe cell-cultured meat scaffolds are a key part of its research. Soy protein isolate (SPI) hydrogel has a three-dimensional network structure and has been studied for L929 cell culture because of its non-toxicity and biocompatibility. However, the toughness and mechanical properties of SPI hydrogel are not enough to bear the requirements of cell cultivation. In this paper, sodium alginate (SA) was added to SPI hydrogel, and the interpenetrating network (IPN) technology was used to construct SPI-SA IPN hydrogel by transglutaminase and Ca2+ double crosslinking method. SPI-SA IPN hydrogel has excellent mechanical properties, structural stability and biodegradable performance than SPI hydrogel. The bio-compatibility and degradability of L929 and C2C12 cells on SPI-SA IPN hydrogel were studied by cytotoxicity, trypan blue and living/dead cell staining, and the growth law of the hydrogel as a scaffold for cell culture was analyzed. The results showed that L929/C2C12 cells can proliferate normally and adhere in hydrogel and have good bio-compatibility. L929 cells with size about 20-50 µm have better adhesion and growth abilities on SPI-SA IPN hydrogel than C2C12 cells with 100-300 µm. Therefore, the SPI-SA IPN hydrogel is non-toxic and supports the growth of cells in the pores of the material. This study provides a reference for the application of SPI-SA IPN hydrogels in vitro cell growth.

Multifunctional Carbon Dots for Biomedical Applications: Diagnosis, Therapy, and Theranostic

Designing suitable nanomaterials is an ideal strategy to enable early diagnosis and effective treatment of diseases. Carbon dots (CDs) are luminescent carbonaceous nanoparticles that have attracted considerable attention. Through facile synthesis, they process properties including tunable light emission, low toxicity, and light energy transformation, leading to diverse applications as optically functional materials in biomedical fields. Recently, their potentials have been further explored, such as enzyme-like activity and ability to promote osteogenic differentiation. Through refined synthesizing strategies carbon dots, a rich treasure trove for new discoveries, stand a chance to guide significant development in biomedical applications. In this review, the authors start with a brief introduction to CDs. By presenting mechanisms and examples, the authors focus on how they can be used in diagnosing and treating diseases, including bioimaging failure of tissues and cells, biosensing various pathogenic factors and biomarkers, tissue defect repair, anti-inflammation, antibacterial and antiviral, and novel oncology treatment. The introduction of the application of integrated diagnosis and treatment follows closely behind. Furthermore, the challenges and future directions of CDs are discussed. The authors hope this review will provide critical perspectives to inspire new discoveries on CDs and prompt their advances in biomedical applications.

Formulation and Characterization of a Novel Oxidized Alginate-Gelatin-Silk Fibroin Bioink with the Aim of Skin Regeneration

Background

In the present study, a novel bioink was suggested based on the oxidized alginate (OAlg), gelatin (GL), and silk fibroin (SF) hydrogels.

Methods

The composition of the bioink was optimized by the rheological and printability measurements, and the extrusion-based 3D bioprinting process was performed by applying the optimum OAlg-based bioink.

Results

The results demonstrated that the viscosity of bioink was continuously decreased by increasing the SF/GL ratio, and the bioink displayed a maximum achievable printability (92 ± 2%) at 2% (w/v) of SF and 4% (w/v) of GL. Moreover, the cellular behavior of the scaffolds investigated by MTT assay and live/dead staining confirmed the biocompatibility of the prepared bioink.

Conclusion

The bioprinted OAlg-GL-SF scaffold could have the potential for using in skin tissue engineering applications, which needs further exploration.

Design of carbon dots for bioimaging and behavior regulation of stem cells

Carbon dots (CDs) have been widely used in bioimaging, biosensing and biotherapy because of their good biocompatibility, optical properties and stability. In this review, we comprehensively summarize the research on CDs in terms of synthesis methods, optical properties and biotoxicity. We describe and envisage the directions for CDs application in stem cell imaging and differentiation, with the aim of stimulating the design of future related CDs. We used 'carbon dots', 'stem cells', 'cell imaging', 'cell differentiation' and 'fate control' as keywords to search for important articles. The Web of Science database was used to extract vital information from a total of 357 papers, 126 review articles and 231 article proceedings within 12 years (2011-2022).

Modification, 3D printing process and application of sodium alginate based hydrogels in soft tissue engineering: A review

Sodium alginate (SA) is an inexpensive and biocompatible biomaterial with fast and gentle crosslinking that has been widely used in biological soft tissue repair/regeneration. Especially with the advent of 3D bioprinting technology, SA hydrogels have been applied more deeply in tissue engineering due to their excellent printability. Currently, the research on material modification, molding process and application of SA-based composite hydrogels has become a hot topic in tissue engineering, and a lot of fruitful results have been achieved. To better help readers have a comprehensive understanding of the development status of SA based hydrogels and their molding process in tissue engineering, in this review, we summarized SA modification methods, and provided a comparative analysis of the characteristics of various SA based hydrogels. Secondly, various molding methods of SA based hydrogels were introduced, the processing characteristics and the applications of different molding methods were analyzed and compared. Finally, the applications of SA based hydrogels in tissue engineering were reviewed, the challenges in their applications were also analyzed, and the future research directions were prospected. We believe this review is of great helpful for the researchers working in biomedical and tissue engineering.

Industrial Manufacture of Enteric Hard Capsules Using Novel Formulations Based on Hypromellose Phthalate/Gelatin and Investigation of Pantoprazole Release

Capsules are popular oral dosage forms because of their ease of production. They are widespread pharmaceutical products. Hard capsules are preferred dosage forms for new medicines undergoing clinical tests because they do not require expansive formulation development. Functional capsules with built-in gastroresistance, aside from the traditional hard-gelatin or cellulose-based vegetarian capsules, would be beneficial. In this research, the effect of polyethylene glycol-4000 (PEG-4000) was investigated on the formulation of uncoated enteric hard capsules based on hypromellose phthalate (HPMCPh) and gelatin. Three different formulations based on HPMCPh, gelatin, and PEG-4000 were tested to achieve the optimal formulation for the industrial production of hard enteric capsules with desired physicochemical and enteric properties. The results reveal that the capsules containing HPMCPh, gelatin, and PEG-4000 (F1) are stable in the stomach environment (pH = 1.2) for 120 min, and during this time, no release happens. The outcomes also demonstrate that PEG-4000 blocks the pores and improves enteric hard capsule formulation. In this research, we present a specific procedure for manufacturing uncoated enteric hard capsules on an industrial scale that does not require an extra coating step for the first time. The industrial-scale validated process can considerably reduce the cost of manufacturing standard enteric-coated dosage forms.

Boosting bone cell growth using nanofibrous carboxymethylated cellulose and chitosan on titanium dioxide nanotube array with dual surface charges as a novel multifunctional bioimplant surface

One of the most vital aspects of the orthopedic implant field has been the development of multifunctional coatings that improve bone-implant contact while simultaneously preventing bacterial infection. The present study investigates the fabrication and characterization of multifunctional polysaccharides, including carboxymethyl cellulose (CMCn) and carboxymethyl chitosan nanofibers (CMCHn), as a novel implant coating on titania nanotube arrays (T). Field emission scanning electron microscopy (FESEM) images revealed a nanofibrous morphology with a narrow diameter for CMCn and CMCHn, similar to extracellular matrix nanostructures. Compared to the T surface, the roughness of CMCn and CMCHn samples increased by over 250 %. An improved cell proliferation rate was observed on CMCHn nanofibers with a positively charged surface caused by the amino groups. Furthermore, in an antibacterial experiment, CMCn and CMCHn inhibited bacterial colony formation by 80 % and 73 %, respectively. According to the results, constructed modified CMCn and CMCHn increased osteoblast cell survival while inhibiting bacterial biofilm formation owing to their surface charge and bioinspired physicochemical properties.

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue

Myocardial infarction is a major cause of death worldwide and remains a social and healthcare burden. Injectable hydrogels with the ability to locally deliver drugs or cells to the damaged area can revolutionize the treatment of heart diseases. Herein, we formulate a thermo-responsive and injectable hydrogel based on conjugated chitosan/poloxamers for cardiac repair. To tailor the mechanical properties and electrical signal transmission, gold nanoparticles (AuNPs) with an average diameter of 50 nm were physically bonded to oxidized bacterial nanocellulose fibers (OBC) and added to the thermosensitive hydrogel at the ratio of 1% w/v. The prepared hydrogels have a porous structure with open pore channels in the range of 50−200 µm. Shear rate sweep measurements demonstrate a reversible phase transition from sol to gel with increasing temperature and a gelation time of 5 min. The hydrogels show a shear-thinning behavior with a shear modulus ranging from 1 to 12 kPa dependent on gold concentration. Electrical conductivity studies reveal that the conductance of the polymer matrix is 6 × 10−2 S/m at 75 mM Au. In vitro cytocompatibility assays by H9C2 cells show high biocompatibility (cell viability of >90% after 72 h incubation) with good cell adhesion. In conclusion, the developed nanocomposite hydrogel has great potential for use as an injectable biomaterial for cardiac tissue regeneration.

Accelerative effect of nanohydrogels based on chitosan/ZnO incorporated with citral to heal the infected full-thickness wounds; an experimental study

Antimicrobial-resistant is a major challenge in to treat infected wounds, and new formulations should be produced. Citral (Citl), chitosan (Chsn), and zinc oxide (ZnO) nanoparticles may accelerate the wound healing process in terms of their antibacterial properties. This new study aimed to investigate the effects of ointments produced from ZnO/Chsn/Citl nanoparticles (NPs) to treat the infected wounds. Following the preparation of ZnO/Chsn/Citl-NPs, swelling behavior, the release of citral, toxicity, and antibacterial properties were evaluated. Base ointment, mupirocin, and ointments made from Chsn-NPs, Chsn/Citl-NPs, and ZnO/Chsn/Citl-NPs were used to treat the mice. The ointments' effects on wound contraction, total bacterial count, and immunofluorescence staining for TNF-α, TGF-β, and bFGF were tested. The synthesis of ZnO/Chsn/Citl-NPs was validated by XRD, FT-IR, DLS, and TEM findings. In higher dilutions, chitosan/citral and ZnO/Chsn/Citl-NPs indicated better antibacterial activity. Nanoparticles were safe up to concentration of the 0.5 mg/mL. The mice in Chsn/Citl and ZnO/Chsn/Citl-NPs treated groups showed higher (P < 0.05) wound contraction ratio and expressions for bFGF, and lower total bacterial count and expressions for TGF-β and TNF-α compared to control mice. Ointments prepared from ZnO/Chsn/Citl-NPs could compete with the commercial ointment of mupirocin and can be used to treat infected wounds after clinical studies.

In vivo biocompatible shape memory polyester derived from recycled polycarbonate e-waste for biomedical application

From the last few decades, the usage of polycarbonate (PC) has tremendously increased due to its engineering properties such as outstanding mechanical strength, superior toughness, and good optical transparency. Owning to these properties, PC has widespread applications in the field of electronics, construction, data storage, automotive industry and subsequently resulted in an ever-increasing volume of post-consumer PC e-waste, which also increases the environmental pollution with time due to its nonbiodegradability nature. Therefore, recycling of PC has become a significant challenge throughout the globe. Herein, we first time reported synthesis of a family of low-cost biodegradable and biocompatible biopolymers using solvent and catalyst free melt polycondensation reaction of recycled PC e-waste derived monomer bis(hydroxyethyl ether) of bisphenol A (BHEEB) along with other renewable resources such as sebacic acid, citric acid and mannitol. The synthesis of the polyester was confirmed by FTIR spectroscopy, NMR spectroscopy, XRD and DSC. The mechanical properties and biodegradation behaviour of the polyester can be fine-tuned by simply varying the monomer feed ratio. In addition to that, the polyester demonstrated excellent shape memory property in ambient temperature along with outstanding recovery properties. In addition to this, the synthesized polyester showed exceptional in vitro and in vivo cytocompatibility as well as cell proliferation rate against mouse fibroblast cells (NIH-3 T3) and biocompatibility, respectively. Therefore, the novel polyesters derived from recycled PC e-waste may be potential resorbable biomaterial for tissue engineering applications in future.

Chitosan/Sodium Alginate/Velvet Antler Blood Peptides Hydrogel Promoted Wound Healing by Regulating PI3K/AKT/mTOR and SIRT1/NF-κB Pathways

Skin wound healing is a principal clinical challenge, and it is necessary to develop effective alternative treatments. Excessive inflammatory response is linked to delayed healing. This study was the first to report a multi-functional chitosan/sodium alginate/velvet antler blood peptides (VBPs) hydrogel (CAVBPH) and explore its potential mechanism to promote wound healing. The results showed that CAVBPH possessed desirable characteristics including thermo-sensitivity, antioxidation, antibacterial activity, biosafety, VBPs release behavior, etc., and significantly accelerated skin wound healing in mice. Specifically, the CAVBPH treatment enhanced cell proliferation, angiogenesis, and extracellular matrix (ECM) secretion, and also relieved inflammation at the wound site compared to the PBS-treated group and blank hydrogel scaffold-treated group. Mechanistically, the efficacy of CAVBPH might be related to the activation of the PI3K/AKT/mTOR and SIRT1/NF-κB pathways. Overall, CAVBPH seems to be a promising therapy for skin repair, probably relying on the abundant short-chain peptides in VBPs.

Assembly encapsulation of BSA and CCCH-ZAP in the sodium alginate/atractylodis macrocephalae system

Zinc finger antiviral proteins (ZAP) can significantly inhibit the replication of avian leukosis virus subgroup J (ALV-J), but the traditional method of ZAP administration is by injection, which can easily cause stress effects in chickens. In this work, we established a sodium alginate/atractylodis macrocephalae system for the encapsulation of CCCH-type zinc finger antiviral protein (CCCH-ZAP). Because of the high cost of ZAP, we first chose bovine serum albumin (BSA) as a model protein to investigate the encapsulation performance. The SEM images clearly confirmed that BSA and the sodium alginate/atractylodis macrocephalae system can assemble easily to form relatively stable nanostructures, and the encapsulation amount of BSA can reach 68%. Subsequently, the encapsulation of ZAP was studied. The SEM and the encapsulation experiments confirmed that ZAP can also be assembly encapsulated in the sodium alginate/atractylodis macrocephalae system with the encapsulation amount of 80%. Release studies showed that the SA/AM-ZAP nanocomposite was able to achieve a release rate of 32% of ZAP. This work successfully confirms the assembly encapsulation of ZAP, which will be beneficial for the usage of ZAP-based animal drugs.

ZAP and BSA can be encapsulated in the sodium alginate/atractylodis macrocephalae system using an assembly method.

Fabrication and Characterization of Bioactive Gelatin-Alginate-Bioactive Glass Composite Coatings on Porous Titanium Substrates

In this research work, the fabrication of biphasic composite implants has been investigated. Porous, commercially available pure Ti (50 vol % porosity and pore distributions of 100-200, 250-355, and 355-500 μm) has been used as a cortical bone replacement, while different composites based on a polymer blend (gelatin and alginate) and bioactive glass (BG) 45S5 have been applied as a soft layer for cartilage tissues. The microstructure, degradation rates, biofunctionality, and wear behavior of the different composites were analyzed to find the best possible coating. Experiments demonstrated the best micromechanical balance for the substrate containing 200-355 μm size range distribution. In addition, although the coating prepared from alginate presented a lower mass loss, the composite containing 50% alginate and 50% gelatin showed a higher elastic recovery, which entails that this type of coating could replicate the functions of the soft tissue in areas of the joints. Therefore, results revealed that the combinations of porous commercially pure Ti and composites prepared from alginate/gelatin/45S5 BG are candidates for the fabrication of biphasic implants not only for the treatment of osteochondral defects but also potentially for any other diseases affecting simultaneously hard and soft tissues.

Harnessing the potential of dialdehyde alginate-xanthan gum hydrogels as niche bioscaffolds for tissue engineering

Biomimetic hydrogels composed of natural polysaccharides have invariably blossomed as niche biomaterials in tissue engineering applications. The prospects of creating an extracellular matrix (ECM)-like milieu from such hydrogels has garnered considerable importance. In this study, we have fabricated bioscaffolds comprising dialdehyde alginate and xanthan gum and explored their potential use in tissue regeneration. The fabricated scaffolds displayed an interconnected porous network structure that is highly desirable for the aforesaid application. The scaffolds were endowed with good mechanical properties, thermostability, protein adsorption efficacy and degradability. Curcumin-loaded hydrogels exhibited appreciable antibacterial activity against E. coli. In vitro cytocompatibility studies revealed that the scaffolds promoted adhesion and proliferation of 3T3 fibroblast cells. The Western blot analysis of p53 gene indicated no growth arrest or apoptosis in 3T3 cells thus, signifying the non-toxic nature of the scaffolds. Furthermore, the ECM formation was confirmed via SDS-PAGE analysis. The overall results clearly validated these scaffolds as effectual biomaterials for tissue engineering applications.