Zwitterionic superabsorbent polymer hydrogels for efficient and selective removal of organic dyes

A novel zwitterionic superabsorbent polymer hydrogel [ZI-SAH] was synthesized by free radical polymerization and used for the removal of crystal violet (CV) and congo red (CR) from an aqueous medium. ZI-SAH was composed of pH-sensitive monomers poly(3-acrylamidopropyl) trimethylammoniumchloride (APTMACl) and 2-acrylamido-2-methylpropanesulphonic acid (AAMPSA). The hydrogel was characterized by SEM and FT-IR spectroscopy, while the visco-elastic behavior was studied using rheological tests. The hydrogel showed a point of zero charge (PZC) at pH 7.2 and high swelling abilities of 3715% at pH 9 and 3112% at pH 5. The cationic crystal violet (CV) and anionic congo red (CR) dyes were employed to investigate the removal ability of ZI-SAH using the batch adsorption method. The materials became more selective towards oppositely charged dyes at pH 5 and 9. The effects of parameters such as contact time, initial concentration of dyes, pH, ZI-SAH dosage and ionic strength on the removal performance were investigated. A kinetic study was carried out via Lagergren pseudo first order and pseudo second order kinetics. The adsorption efficiencies of ZI-SAH were 13.6 mg g⁻¹ for CV and 9.07 mg g⁻¹ for CR with % removal values of 97 and 89, respectively. The thermodynamic parameters, namely, ΔG°, ΔH° and ΔS° were determined, and the negative value of free energy showed that the process of adsorption was spontaneous. ZI-SAH was recycled and reused in five consecutive cycles with removal efficiency > 75%.

A novel zwitterionic superabsorbent polymer hydrogel [ZI-SAH] was synthesized by free radical polymerization and used for the removal of crystal violet (CV) and congo red (CR) from an aqueous medium.     

A freeze–thaw PVA hydrogel loaded with guava leaf extract: physical and antibacterial properties

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity. This study succeeded in fabricating a PVA hydrogel containing GLE using the freeze–thaw (FT) method. By varying the GLE concentration, we can adjust the physical properties of the hydrogel. The addition of GLE results in a decrease in cross-linking during gelation and an increase in the pore size of the hydrogels. The increase of the pore size made the swelling increase and the mechanical strength decrease. The weight loss of the hydrogel also increases because the phosphate buffer saline (PBS) dissolves the GLE. Increasing the GLE concentration caused the Fourier-transform infrared (FTIR) absorbance peaks to widen due to hydrogen bonds formed during the FT process. The crystalline phase was transformed into an amorphous phase in the PVA/GLE hydrogel based on the X-ray diffraction (XRD) spectra. The differential scanning calorimetry (DSC) characterization showed a significant decrease in the hydrogel weight over temperatures of 30–150 °C due to the evaporation of water from the hydrogel matrix. The zone of inhibition of the PVA/GLE hydrogel increased with antibacterial activity against Staphylococcus aureus of 17.93% per gram and 15.79% per gram against Pseudomonas aeruginosa.

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity.     

Sintered porous Ti6Al4V scaffolds incorporated with recombinant human bone morphogenetic protein-2 microspheres and thermosensitive hydrogels can enhance bone regeneration

A well-controlled powder sintering technique was used to fabricate porous Ti6Al4V scaffold. The thermosensitive chitosan thioglycolic acid (CS-TA) hydrogel was used as a carrier to inject recombinant human bone morphogenetic protein-2 (rhBMP-2) microspheres into pores of the Ti6Al4V scaffold at 37 °C, and then the porous Ti6Al4V/rhBMP-2 loaded hydrogel composite was obtained. The bare Ti6Al4V scaffold was used as the control. The characteristics and mechanical properties of the scaffold, rheological properties of the hydrogels and the rhBMP-2 loaded hydrogel, the release of the rhBMP-2 loaded hydrogel, and the biological properties of the two types of samples were evaluated by in vitro and in vivo tests. Results indicated that the sintered porous Ti6Al4V had high porosity, large pore size with good mechanical properties. The hydrogel and rhBMP-2 loaded hydrogel showed thermosensity. The rhBMP-2 loaded hydrogel showed a stable and extended release profile without too high burst release of rhBMP-2. Both groups showed good biocompatibility and osteogenic ability. However, according to the results of cell tests and implantation, the group with rhBMP-2 loaded hydrogel had significantly higher cell proliferation rate, faster bone growth speed, and more bone ingrowth at every time point. Therefore, the sintered porous Ti6Al4V scaffolds incorporated with rhBMP-2 microspheres and CS-TA hydrogel was effective in enhancing the bone regeneration, and prospects a good candidate for application in orthopedics.

Porous Ti6Al4V scaffolds incorporated with rhBMP-2 microspheres and CS-TA hydrogel can enhance the bone regeneration.     

Preparation and characterization of a novel drug-loaded Bi-layer scaffold for cartilage regeneration

The incidence of articular cartilage defects is increasing year by year. In order to repair the cartilage tissue at the defect, scaffolds with nanofiber structure and biocompatibility have become a research hotspot. In this study, we designed and fabricated a bi-layer scaffold prepared from an upper layer of drug-dispersed gelatin methacrylate (GELMA) hydrogel and a lower layer of a drug-encapsulated coaxial fiber scaffold prepared from silk fiber (SF) and polylactic acid (PLA). These bi-layer scaffolds have porosity (91.26 ± 3.94%) sufficient to support material exchange and pore size suitable for cell culture and infiltration, as well as mechanical properties (2.65 ± 0.31 MPa) that meet the requirements of cartilage tissue engineering. The coaxial fiber structure exhibited excellent drug release properties, maintaining drug release for 14 days in PBS. In vitro experiments indicated that the scaffolds were not toxic to cells and were amenable to chondrocyte migration. Notably, the growth of cells in a bi-layer scaffold presented two states. In the hydrogel layer, cells grow through interconnected pores and take on a connective tissue-like shape. In the coaxial fiber layer, cells grow on the surface of the coaxial fiber mats and appeared tablet-like. This is similar to the structure of the functional partitions of natural cartilage tissue. Together, the bi-layer scaffold can play a positive role in cartilage regeneration, which could be a potential therapeutic choice to solve the current problems of clinical cartilage repair.

The picture shows the preparation process of the cartilage scaffold, in which the hydrogel layer is loaded with aescin sodium, and the fiber layer is loaded with kartogenin.     

Tetracycline hydrochloride loaded citric acid functionalized chitosan hydrogel for wound healing

Citric modified chitosan (CC) hydrogel containing antibacterial drugs is developed by the freezing and thawing treatment method. The SEM image of the CC hydrogel revealed a porous structure. The rheological properties, porosity, swelling rate, water uptake, tensile properties and in vitro degradation were found to be tunable via CC concentration. To enhance antibacterial properties, tetracycline hydrochloride (TH) representing the drug model, was integrated into the CC hydrogel. The cumulative release of drug was also tunable via CC concentration. The drug loaded CC hydrogel showed enhanced antimicrobial activity against E. coli and S. aureus. In animal tests, it was found the TH loaded CC hydrogel accelerated the healing of the wounds created on rats. These results suggest that the drug loaded CC hydrogel has a promising future in wound healing as a wound dressing.

Citric modified chitosan (CC) hydrogel containing antibacterial drug for wound healing applications.     

Cell-loaded injectable gelatin/alginate/LAPONITE® nanocomposite hydrogel promotes bone healing in a critical-size rat calvarial defect model

Injectable hydrogels have long been gaining attention in the bone tissue engineering field owing to their ability to mix homogeneously with cells and therapeutic agents, minimally invasive administration, and seamless defect filling. Despite the advantages, the use of injectable hydrogels as cell delivery carriers is currently limited by the challenge of mimicking the natural microenvironment of the loaded cells, promoting cell proliferation, and enhancing bone regeneration. To overcome these problems, we aimed to develop an injectable and in situ-forming nanocomposite hydrogel composed of gelatin, alginate, and LAPONITE® to mimic the architecture and composition of the extracellular matrix. The encapsulated rat bone marrow mesenchymal stem cells (rBMSCs) survived in the nanocomposite hydrogel, and the gel promoted cell proliferation in vitro. Systematic in vivo research of the biomimetic hydrogel with or without cells was conducted in a critical-size (8 mm) rat bone defect model. The in vivo results proved that the hydrogel loaded with rBMSCs significantly promoted bone healing in rat calvarial defects, compared to the hydrogel without cells, and that the hydrogel did not provoked side effects on the recipients. Given these advantageous properties, the developed cell-loaded injectable nanocomposite hydrogel can greatly accelerate the bone healing in critical bone defects, thus providing a clinical potential candidate for orthopedic applications.

An injectable cell-laden nanocomposite hydrogel simulate natural ECM, promote cell proliferation, and accelerate bone healing of critical-size rat calvarial defects.     

Formulation development,in vitro and in vivo evaluation of chitosan engineered nanoparticles for ocular delivery of insulin

Insulin-dependent diabetic patients have to count on the administration of painful and discomforting insulin injections. However, inadequate insulin absorption and the risk of insulin level escalation in the blood are some disadvantages associated with insulin therapy. Thus, the current study intends to formulate insulin-loaded chitosan nanoparticles for refining the systemic absorption of insulin via the ocular route. Insulin-loaded chitosan nanoparticles were prepared by the ionotropic gelation method and characterized for various parameters. Optimized insulin loaded nanoparticles (C4T4I4) were positively charged with a particle size of 215 ± 2.5 nm and showed 65.89 ± 4.3% entrapment efficiency. The in vitro drug release exhibited sustained release of insulin, where 77.2 ± 2.1% of release was observed after 12 h and leads to an assumption of the non-Fickian diffusion release mechanism. The permeation study discloses good mucoadhesive and better permeation properties of insulin loaded nanoparticles compared to free Insulin. No significant difference was observed in the size of particles after six months of storage, signifying their adequate stability. Nanoparticles were found to be non-irritant to ocular tissues and exhibited prominent blood glucose level reduction in vivo. The outcomes of this study suggested that the chitosan nanoparticulate system could act as a prominent carrier system for insulin with enhanced stability and efficacy.

Insulin-dependent diabetic patients have to count on the administration of painful and discomforting insulin injections.     

Electromagnetic field-assisted cell-laden 3D printed poloxamer-407 hydrogel for enhanced osteogenesis

3D bioprinted hydrogel has gained enormous attention, especially in tissue engineering, owing to its attractive structure and excellent biocompatibility. In this study, we demonstrated that 3D bioprinted cell-laden ‘thermoresponsive’ poloxamer-407 (P407) gels have the potential to stimulate osteogenic differentiation of apical papilla stem cells (SCAPs) under the influence of low voltage–frequency (5 V–1 Hz, 0.62 mT) electromagnetic fields (EMFs). SCAPs were initially used for cell-laden 3D printing to biomimic the apical papilla of human teeth. The developed hydrogel exhibited higher mechanical strength as well as good printability, showing high-quality micro-architecture. Moreover, the as-printed hydrogels (5 mm × 5 mm) were loaded with plasminogen activator inhibitor-1 (PAI-1) for testing the combined effect of PAI-1 and EMFs on SCAP differentiation. Interestingly, the 3D hydrogels showed improved viability and differentiation of SCAPs under EMFs'' influence as examined by live/dead assay and alizarin Red-S staining, respectively. Therefore, our results confirmed that P407 hydrogels are non-toxic for encapsulation of SCAPs, yielding high cell viability and accelerate the cell migration potential. The 3D hydrogels with PAI-1 exhibited high mRNA expression levels for osteogenic/odontogenic gene markers (ALP, Col-1, DSPP, and DMP-1) vis-à-vis control after 14 days of in vitro culture. Our findings suggest that 3D bioprinted P407 hydrogels are biocompatible for SCAP encapsulation, and the applied low voltage–frequency EMFs could effectively improve dental tissue regeneration, particularly for oral applications.

3D bioprinted ‘mini-tooth’ respond to low voltage-frequency electromagetic fields (EMFs) stimulation and promote differentiation of apical papilla stem cells (SCAPs).     

Fabrication of superwetting,antimicrobial and conductive fibrous membranes for removing/collecting oil contaminants

In order to remove/collect organic contaminants from polluted water, polypyrrole/silver nanoparticles (PPy/Ag NPs) have been loaded onto spandex fabric using the method of in situ redox-oxidation polymerization to achieve a specific membrane. Observations showed that the original hydrophobic fabric became superhydrophilic and superoleophobic underwater (with an underwater oil contact angle (OCA) of 160°). The as-prepared specimen could effectively remove the oil from an oil-in-water emulsion. After further hydrophobic modification, the specimen was transformed into a fabric that possessed durable superhydrophobicity and superlipophilicity (with a water contact angle (WCA) of 159°), which could collect the oil from a water-in-oil emulsion. Apparently, the two types of fibrous membranes completely satisfied the conditions for removing/collecting organic contaminants from opposite types of water/oil mixtures. The durable evaluation results exhibited the outstanding resistance of both fibrous membranes to friction and acidic and basic scouring agents. Additionally, the multifunctional fabric membrane also possessed excellent electrical conductivity and antibacterial activities towards S. aureus, B. subtilis, and E. coli, which will greatly promote developments in the textile industry and provide a bright future for fabric-based materials.

In order to remove/collect organic contaminants from polluted water, polypyrrole/silver nanoparticles (PPy/Ag NPs) have been loaded onto spandex fabric using the method of in situ redox-oxidation polymerization to achieve a specific membrane.     

Chitin/egg shell membrane@Fe3O4 nanocomposite hydrogel for efficient removal of Pb2+ from aqueous solution

The development of adsorbents by using the byproducts or waste from large-scale industrial and agricultural production is of great significance, and is considered to be an economic and efficient strategy to remove the heavy metals from polluted water. In this work, a novel chitin/EM@Fe₃O₄ nanocomposite hydrogel was obtained from a NaOH/urea aqueous system, where the proteins of egg shell membrane and Fe₃O₄ nanoparticles were chemically bonded to chitin polymer chains with the help of epichlorohydrin. Due to the existence of a large number of –NH₂, –OH, –CONH–, –COOH and hemiacetal groups, the adsorption efficiency for Pb²⁺ into the absorbent was dramatically enhanced. The experimental results revealed that the adsorption behavior strongly depends on various factors, such as initial pH, initial Pb²⁺ concentration, incubation temperature and contact time. The kinetic experiments indicated that the adsorption process for Pb²⁺ in water solution agreed with the pseudo-second-order kinetic equation. The film diffusion or chemical reaction is the rate limiting process in the initial adsorption stage, and the adsorption of Pb²⁺ into the nanocomposite hydrogel can well fit the Langmuir isotherm. Thermodynamic analysis demonstrated that such adsorption behaviors were dominated by an endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) process.

A novel kind of chitin/EM@Fe₃O₄ nanocomposite hydrogel derived from the biowastes of egg shell membrane and chitin was successfully prepared for efficient removal of Pb²⁺ from wastewater solution.     

Strategy to design a smart photocleavable and pH sensitive chitosan based hydrogel through a novel crosslinker: a potential vehicle for controlled drug delivery

We report herein the synthesis of a novel photocleavable crosslinker, 4-formylphenyl 4-((4-formylphenoxy)methyl)-3-nitrobenzoate (CHO–ONB–CHO) and its joining with amine-based polysaccharides, viz. chitosan, resulting in the formation of a dual stimuli-responsive (ONB–chitosan) hydrogel having UV- and pH-responsive sites. The detailed mechanism for the formation of CHO–ONB–CHO and ONB–chitosan hydrogel is proposed. The (CHO–ONB–CHO) crosslinker was characterized using ¹H-NMR, LCMS and UV-visible spectroscopy. The dual responsive hydrogel is characterized by FTIR, SEM, XRD, DSC and TGA. The crosslinked hydrogel displayed mechanical robustness with a storage modulus of about 1741 pa. The pH-responsiveness of the hydrogel was studied via equilibrium swelling studies in various pH media at 37 °C. The photocleavable behavior of the crosslinker was observed in the UV-absorption range of 310–340 nm and the hydrogel exhibited maximum swelling at pH 5.7. The higher swelling of the hydrogel in acidic conditions and its photo-responsiveness can be exploited for the controlled, temporal and spatial release of therapeutic drugs at any inflammatory areas with acidic environments. It was observed that the hydrogel exhibited higher drug release at pH 5.7 than at pH 7.4.

We report the synthesis of a novel photocleavable crosslinker and its joining with amine-based polysachharides, viz. chitosan, resulting in the formation of a dual stimuli-responsive hydrogel having UV- and pH-responsive sites.     

Highly tough and rapid self-healing dual-physical crosslinking poly(DMAA-co-AM) hydrogel

Introducing double physical crosslinking reagents (i.e., a hydrophobic monomer micelle and the LAPONITE® XLG nano-clay) into the copolymerization reaction of hydrophilic monomers of N,N-dimethylacrylamide (DMAA) and acrylamide (AM) is reported here by a thermally induced free-radical polymerization method, resulting in a highly tough and rapid self-healing dual-physical crosslinking poly(DMAA-co-AM) hydrogel. The mechanical and self-healing properties can be finely tuned by varying the weight ratio of nanoclay to DMAA. The tensile strength and elongation at break of the resulting nanocomposite hydrogel can be modulated in the range of 7.5–60 kPa and 1630–3000%, respectively. Notably, such a tough hydrogel also exhibits fast self-healing properties, e.g., its self-healing rate reaches 48% and 80% within 2 and 24 h, respectively.

Introducing a micelle and LAPONITE® XLG nano-clay into N,N-dimethylacrylamide (DMAA)/acrylamide (AM) copolymerization reactions results in a highly tough and rapid self-healing dual-physical crosslinking poly(DMAA-co-AM) hydrogel.     

Allergic Contact Dermatitis from Topical Acyclovir: Case Series

Background

Despite the widespread use of oral or topical acyclovir, allergic contact dermatitis caused by it has been rarely reported, with fewer than 20 case studies published in the English literature to date.

Nanofibrous artificial skin substitute composed of mPEG–PCL grafted gelatin/hyaluronan/chondroitin sulfate/sericin for 2nd degree burn care: in vitro and in vivo study

The aim of this study was to investigate the efficacy of a skin substitute composed of mPEG–PCL–grafted-gelatin (Bio-Syn)/hyaluronan/chondroitin sulfate/sericin and to study its in vitro biocompatibility with human fibroblasts, human keratinocytes and hMSCs in terms of cellular adhesion and proliferation (∼5–6 fold). mPEG–PCL was grafted into a gelatin backbone via a Michael addition reaction to prepare Bio-Syn and it was characterized using ATR-FTIR, ¹H NMR and TNBS assay. Additionally, keratinocyte–hMSC contact co-culture studies showed that Bio-Syn composite scaffolds loaded with sericin promote hMSCs’ epithelial differentiation with regard to qRT-PCR gene expression (ΔNp63α and keratin 14) and expression of various epithelial markers (Pan-cytokeratin, ΔNp63α and keratin 14). In vivo efficacy studies on a 2^nd degree burn wound model in Wistar rats showed an improved rate of wound contraction, histology (H&E and Van Gieson’s staining) and pro-healing marker (hexosamine, hydroxyproline, etc.) expression in granular tissue compared to using the commercial dressing Neuskin™ and a cotton gauze control.

The paper demonstrates the fabrication of sericin loaded hybrid polymeric composite nanofibrous scaffold and evaluation of its cytocompatibilty in three human monocultures and biocompatibility in second degree burn wound model in Wistar rats.     

Multi-responsive and conductive bilayer hydrogel and its application in flexible devices

Multi-stimuli-responsive hydrogels are intelligent materials that present advantages for application in soft devices compared with conventional machines. In this paper, we prepared a bilayer hydrogel consisting of a poly(2-(dimethylamino)ethyl methacrylate) layer and a poly(N-isopropylacrylamide) layer. The hydrogel responded to temperature, pH, NaCl, and ethanol by undergoing bending deformation. At 40 °C, it only took 23 s for the hydrogel to bend nearly 300°. Carbon black was also introduced into the hydrogel network to render it conductive. Based on its multi-stimuli-responsive properties and conductivity, the hydrogel was used to construct a 4-arm gripper, thermistor, and finger movement monitor. The time required to grip and release an object was 141 s. The resistance changed with temperature, which affected the brightness of an LED. Finger motions were monitored, and the bending angle could be distinguished.

A multi-stimuli-responsive bilayer hydrogel with conductivity has potential for application as soft robots, multi-stimuli-dependent resistors and human body monitors.     

Synthesis of nanomedicine hydrogel microcapsules by droplet microfluidic process and their pH and temperature dependent release

Chitosan and alginate hydrogels are attractive because they are highly biocompatible and suitable for developing nanomedicine microcapsules. Here we fabricated a polydimethylsiloxane-based droplet microfluidic reactor to synthesize nanomedicine hydrogel microcapsules using Au@CoFeB–Rg3 as a nanomedicine model and a mixture of sodium alginate and PEG-g-chitosan crosslinked by genipin as a hydrogel model. The release kinetics of nanomedicines from the hydrogel were evaluated by simulating the pH and temperature of the digestive tract during drug transport and those of the target pathological cell microenvironment. Their pH and temperature-dependent release kinetics were studied by measuring the mass loss of small pieces of thin films formed by the nanomedicine-encapsulating hydrogels in buffers of pH 1.2, 7.4, and 5.5, which replicate the pH of the stomach, gut and blood, and cancer microenvironment, respectively, at 20 °C and 37 °C, corresponding to the storage temperature of hydrogels before use and normal body temperature. Interestingly, nanomedicine-encapsulating hydrogels can undergo rapid decomposition at pH 5.5 and are relatively stable at pH 7.4 at 37 °C, which are desirable qualities for drug delivery, controlled release, and residue elimination after achieving target effects. These results indicate that the designed nanomedicine hydrogel microcapsule system is suitable for oral administration.

A kind of pH and temperature dependent interpenetrating hydrogel was designed and synthesized via crosslinking of alginate and polyethylene-glycol grafting chitosan by genipin for encapsulated nanomedicine with controlled release.     

Dual-scale TiO2 and SiO2 particles in combination with a fluoroalkylsilane and polydimethylsiloxane superhydrophobic/superoleophilic coating for efficient solvent–water separation

Surfaces that have unique wettabilities and are simultaneously superhydrophobic with water contact angles > 150°, and superoleophilic with oil contact angles < 5°, are of critical importance in the oil/solvent–water separation field. This work details the facile preparation of highly efficient oil–water separation devices that successfully combine hierarchical surface roughening particles and low surface energy components with porous substrates. Coatings were generated using TiO₂ and hydrophobic-SiO₂ micro/nanoparticle loadings which were then embedded within polydimethylsiloxane, commercially known as Sylgard® 184, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS) polymer mixtures. The resulting slurries were dip coated onto copper meshes with varying pore diameters (30, 60 and 100 meshes had 595, 250 and 149 μm pore dimensions respectively). Functional testing proved that mesh substrates coated in the lowest Sylgard® 184 : FAS polymer ratio formulations displayed heightened water repellency and retained their superoleophilic properties upon repeat testing. The largest average water contact angle of 145 ± 1°, was recorded on a copper 30 mesh substrate with a coating comprising H-SiO₂ microparticles and TiO₂ nanoparticles in a 1 : 9 polymer mixture of Sylgard® and FAS. The coating''s extreme oil affinity was supported by high solvent–water separation efficiencies (≥99%) which withstood numerous testing/washing cycles.

Surfaces that have unique wettabilities and are simultaneously superhydrophobic with water contact angles > 150°, and superoleophilic with oil contact angles < 5°, are of critical importance in the oil/solvent–water separation field.     

A pH-sensitive and sustained-release oral drug delivery system: the synthesis,characterization, adsorption and release of the xanthan gum-graft-poly(acrylic acid)/GO–DCFP composite hydrogel

In this study, graphene oxide (GO) was successfully prepared using the improved Hummers method, and the prepared GO powder was dissolved in distilled water and subjected to ultrasonic stripping. Diclofenac potassium (DCFP) was selected as a model drug to systematically evaluate the adsorption mechanism of DCFP by GO. Different reaction models were constructed to fit the adsorption kinetics and adsorption isotherms of DCFP on GO, in order to further explore the underlying adsorption mechanism. The results demonstrated that the pseudo-second-order kinetic model and Freundlich model could better delineate the adsorption process of DCFP by GO. Both π–π stacking and hydrophobic interaction were mainly involved in the adsorption process, and there were electrostatic interaction and hydrogen bonding at the same time. Then, the xanthan gum-graft-poly(acrylic acid)/GO (XG-g-PAA/GO) composite hydrogel was synthesized by in situ polymerization as a slow-release drug carrier. For this reason, a XG-g-PAA/GO–DCFP composite hydrogel was synthesized, and its in vitro drug release and pharmacokinetic data were assessed. The results showed that the synthesized XG-g-PAA/GO composite hydrogel had a certain mechanical strength and uniform color, indicating that GO is evenly distributed in this composite hydrogel. Moreover, the results of a swelling ratio test demonstrated that the swelling ratios of the XG-g-PAA/GO composite hydrogel were significantly increased with increasing pH values, implying that this material is sensitive to pH. The in vitro drug release experiment showed that the cumulative release of DCFP after 96 h was significantly higher in artificial intestinal fluid than in artificial gastric fluid. These findings indicate that the XG-g-PAA/GO–DCFP composite hydrogel exhibits pH sensitivity under physiological conditions. Besides, the results of in vivo pharmacokinetic analysis revealed that the t_1/2 of DCFP group was 2.03 ± 0.35 h, while that of the XG-g-PAA/GO–DCFP composite hydrogel group was 10.71 ± 2.04 h, indicating that the synthesized hydrogel could effectively prolong the drug action time. Furthermore, the AUC_(0–t) of the DCFP group was 53.99 ± 3.18 mg L⁻¹ h⁻¹, while that of the XG-g-PAA/GO–DCFP composite hydrogel group was 116.79 ± 14.72 mg L⁻¹ h⁻¹, suggesting that the bioavailability of DCFP is greatly enhanced by this composite hydrogel. In conclusion, this study highlights that the XG-g-PAA/GO–DCFP composite hydrogel can be applied as a sustained-release drug carrier.

In this study, graphene oxide (GO) was successfully prepared using the improved Hummers method, and the prepared GO powder was dissolved in distilled water and subjected to ultrasonic stripping.     

Bio-inspired microcapsule for targeted antithrombotic drug delivery

Thrombosis or embolism is the leading cause of death and long-term adult disability worldwide. To reduce the risk of thrombosis and hemorrhaging in patients, a facile and versatile method was developed to fabricate microcapsules for targeted antithrombotic drug delivery. The microcapsules were prepared via oxidative polymerization of dopamine on polystyrene microspheres, followed by immobilization of fibrinogen onto the surface of poly(dopamine) layers. Subsequently, microcapsules were obtained by removing the cores with THF. Nattokinase was loaded into the microcapsules via diffusion. The loading amount was approximately 0.05 mg g⁻¹ at 37 °C, and the loading efficiency was nearly 75%, based on the initial concentration of nattokinase in PBS. The release of nattokinase was a gradual process at 37 °C, and the activity of the targeted activated platelets was highly efficient. The antithrombotic activity of the nattokinase microcapsules was evidenced by the sharp dissolution of fibrin clots and the blood clotting time indexes. A gradual release mechanism of platelet-inspired microcapsules used for targeted antithrombotic therapy was proposed. This strategy for targeted antithrombotic drug delivery, which lowers the demand dose and minimizes side effects while maximizing drug efficacy, provides a potential new way to treat life-threatening diseases caused by vascular disruption.

NK-loaded hollow microcapsules were fabricated and assessed as a potential antithrombosis therapy.