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Novel co-operative immuno-photodynamic therapy nanoparticles, targeting tumor-associated macrophages, modulating the tumor microenvironment, and preventing tumor metastasis by skewing TAMs to M1-like cells, have been developed.

PCL nanofibrous scaffolds are widely used as bone scaffolds, and they can increase the efficiency of bone regeneration by loading drugs and/or growth factors onto them. However, to obtain a more effective bone regeneration effect, it is necessary to increase drug loading and release efficiency. In this study, conductive hydrogel forming nanofibrous scaffolds were prepared to increase drug efficiency. GO has an excellent conductivity and biocompatibility, making it an efficient conductive polymer for bone differentiation. Electrospun PCL was immersed in a mixed solution of GO and PVP and then crosslinked using gamma-ray irradiation. It was confirmed that GO/PVP-PCL was successfully prepared through its characterization (morphology, thermal, chemical, electrical, and biological properties). In addition, drug-release efficiency was confirmed by electrical stimulation after loading the sample with BMP-2, a bone-regeneration growth factor. Compared to PCL, it was confirmed that GO/PVP-PCL has an approximately 20% improved drug-release efficiency and an excellent mineralization of the scaffolds using SBF. After culturing MG63 cells on GO/PVP-PCL, a high effect on osteodifferentiation was confirmed by ALP activity. Therefore, GO/PVP-PCL prepared by a gamma-ray-induced crosslinking reaction is expected to be used as biomaterial for bone-tissue engineering.

In an immunosuppressive tumor microenvironment, tumor-associated macrophages (TAMs) are the most abundant cells displaying pro-tumorigenic M2-like phenotypes, encouraging tumor growth and influencing the development of resistance against conventional therapies. TAMs are highly malleable. They can be repolarized into tumoricidal M1-like cells. In this study, we report the synthesis of novel co-operative immuno-photodynamic nanoparticles involving TAM self-targeting acrylic acid grafted mannan (a polysaccharide) conjugated with the chlorin e6 (Ce6) photosensitizer and then loaded with resiquimod (R848), a toll-like receptor (TLR7/8) agonist. The mannan conjugated Ce6 loaded with R848 (MCR) as bioconjugate nanoparticles demonstrated selective targeting of anti-inflammatory M2-like cells. Using photodynamic therapy they were repolarized to pro-inflammatory M1-like cells with combined effects of reactive oxygen species (ROS)-triggered intracellular signaling and a small-molecule immunostimulant. The MCR also demonstrated a TAM-directed adaptive immune response, inhibited tumor growth, and prevented metastasis. Our results indicate that these MCR nanoparticles can effectively target TAMs and modulate them for cancer immunotherapy.

The effectiveness of small-diameter vascular grafts depends on their antithrombogenic properties and ability to undergo accelerated endothelialization. The extreme hydrophobic nature of poly(ε-caprolactone) (PCL) hinders vascular tissue integration, limiting its use in medical implants. To enhance the antithrombogenicity of PCL as a biomaterial, we grafted 2-aminoethyl methacrylate (AEMA) hydrochloride onto the PCL surface using gamma irradiation; developed a biodegradable heparin-immobilized PCL nanofibrous scaffold using gamma irradiation and N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride/N-hydroxysuccinimide reaction chemistry; and incorporated vascular endothelial growth factor (VEGF) into the scaffold to promote vascular endothelial cell proliferation and prevent thrombosis on the vascular grafts. We assessed the physicochemical properties of PCL, heparin-AEMA-PCL (H-PCL), and VEGF-loaded heparin-AEMA-PCL (VH-PCL) vascular grafts using scanning electron microscopy, attenuated total reflection–Fourier transform infrared spectroscopy, toluidine blue O staining, and fibrinogen adsorption and surface wettability measurement. In addition, we implanted the vascular grafts into 24-month-old Sprague Dawley rats and evaluated them for 3 months. The H-PCL and VH-PCL vascular grafts improved the recovery of blood vessel function by promoting the proliferation of endothelial cells and preventing thrombosis in clinical and histological evaluation, indicating their potential to serve as functional vascular grafts in vascular tissue engineering.

Background Clinical characteristics of patients with masked uncontrolled hypertension (MUCH) are poorly defined, and few studies have reported on clinical predictors of MUCH. We investigated demographic, lifestyle, clinical and blood pressure (BP) characteristics in patients with MUCH and proposed a prediction model for MUCH. Method We analyzed 2044 subjects taking antihypertensive medication enrolled in the Korean Ambulatory Blood Pressure Monitoring (Kor-ABP) registry, who were categorized into controlled hypertension (n=481, normal office BP, normal 24-hour ABP), pseudo-uncontrolled hypertension (n=131, high office BP, normal 24-hour ABP), MUCH (n=380, normal office BP, high 24-hour ABP), and sustained uncontrolled hypertension (n=1,052; high office BP and high 24-hour ABP). Result The prevalence of MUCH increased with office systolic BP (SBP) and diastolic BP (DBP), whereas it was not associated with the numbers of antihypertensive drugs. But in patients with a high office SBP (≥130 mmHg), the prevalence of MUCH increased with decreasing numbers of antihypertensive drugs (interaction p=0.008; Figure 1A). Multiple logistic regression analysis identified high office SBPs and DBPs, prior stroke, dyslipidemia and single anti-hypertensive agent use as independent predictors of MUCH (Table 1). A prediction model using these predictors showed a high diagnostic accuracy (C-index 0.833) and a goodness of fit for the presence of MUCH (Figure 1B). Conclusion MUCH is associated with the borderline increase in office BP and the underuse of anti-hypertensive drugs as well as dyslipidemia and prior stroke, which underscores the importance of achieving the optimal BP control level in the high risk patients. The proposed model would accurately predict MUCH in patients with controlled office BP. Figure 1 Funding Acknowledgement Type of funding source: None

Bioelectrodes, including metallic and conductive polymer (CP) bioelectrodes, often suffer from biofouling by contamination from microbacteria and/or biomolecules in biological systems, which can cause substantial impairment of biofunctionality and biocompatibility. Herein, we have employed an in situ polymerization of methacryloyloxyethyl phosphorylcholine (MPC) by gamma radiation to introduce fouling-resistant properties onto the surface of the conductive polymer, polypyrrole (PPy). The concentrations of an MPC monomer were varied during the grafting. PPy electrodes modified with MPC (PPy-g-MPC) revealed excellent anti-biofouling properties, as demonstrated by multiple analyses, such as serum protein adsorption, fibroblast adhesion, bacteria adhesion, and scar tissue formation in vivo. Importantly, PPy-g-MPC, which was modified with 0.2 M MPC using gamma radiation, exhibited electrical properties similar to unmodified PPy electrodes, indicating that our MPC grafting strategies did not cause impairment of electrical/electrochemical properties of the original PPy electrodes while successfully introducing anti-biofouling properties. Zwitterionic MPC polymer grafting on PPy electrodes by in situ polymerization with gamma radiation will benefit the development of highly biocompatible and functional bioelectrodes, such as neural electrodes, stimulators, and biosensors.

Growth factors have been used to regenerate specific tissue structures by stimulating proliferation and migration of target cells, as well as regulating differentiation of various stem cells. To improve tissue regeneration, growth factors need effective delivery carriers to effect their long-term and sustained release to the target region. For this reason, we fabricated a valuable growth factor delivery carrier termed fibrous particles (FPs) with a morphology similar to that of the extracellular matrix (ECM). These FPs were prepared by aminolysis of poly(L-lactic acid) nanofibrous sheets and modified for sustaining growth factor delivery by heparinization (to produce Hep-FPs). We confirmed that Hep-FPs showed stable bone morphogenetic protein-2 (BMP-2) binding and sustained BMP-2 releasing. In addition, the released BMP-2 from the Hep-FPs successfully improved alkaline phosphatase activity and mineralization of human mesenchymal stem cells in vitro. To demonstrate the effect of bone regeneration using the BMP-2 delivery carrier, we implanted FPs, Hep-FPs, FPs-BMP-2, and Hep-FPs-BMP-2 onto a critically sized region of a mouse calvarial defect (∅ 4 mm). After 8 weeks of treatment, Hep-FPs-BMP-2 exhibited broader new bone formation and much higher bone density at the defect area than did the other particles. Therefore, FPs resembling the ECM can be used as an instructive tool for a variety of tissue regeneration purposes.

Sung In Jeong,1,* Seong-Cheol Park,2,* Sun-Jeong Park,2,* Eun-Ji Kim,2 Hun Heo,2 Jong-Seok Park,1 Hui-Jeong Gwon,1 Youn-Mook Lim,1 Mi-Kyeong Jang2 1Research Division for Industry and Environment, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 2Department of Polymer Science and Engineering, College of Engineering, Sunchon National University, Suncheon, Korea *These authors contributed equally to this work Introduction: Although numerous studies have been conducted with the aim of developing drug-delivery systems, chemically synthesized gene carriers have shown limited applications in the biomedical fields due to several problems, such as low-grafting yields, undesirable reactions, difficulties in controlling the reactions, and high-cost production owing to multi-step manufacturing processes. Materials and methods: We developed a 1-step synthesis process to produce 2-aminoethyl methacrylate-grafted water-soluble chitosan (AEMA-g-WSC) as a gene carrier, using gamma irradiation for simultaneous synthesis and sterilization, but no catalysts or photoinitiators. We analyzed the AEMA graft site on WSC using 2-dimensional nuclear magnetic resonance spectroscopy (2D NMR; 1H and 13C NMR), and assayed gene transfection effects in vitro and in vivo. Results: We revealed selective grafting of AEMA onto C6-OH groups of WSC. AEMA-g-WSC effectively condensed plasmid DNA to form polyplexes in the size range of 170 to 282 nm. AEMA-g-WSC polyplexes in combination with psi-hBCL2 (a vector expressing short hairpin RNA against BCL2 mRNA) inhibited tumor cell proliferation and tumor growth in vitro and in vivo, respectively, by inducing apoptosis. Conclusion: The simple grafting process mediated via gamma irradiation is a promising method for synthesizing gene carriers. Keywords: water-soluble chitosan, 2-aminoethyl methacrylate, gamma irradiation, gene delivery

Polycaprolactone (PCL) has been considered a useful material for orthopedic devices and osseous implants because of its biocompatibility and bone-forming activity. However, PCL-based scaffolds have hydrophobic surfaces that reduce initial cell viability. In this study, we fabricated surface-modified PCL nanofibers for tissue engineering using radiation technology. We supplemented the hydrophilicity of the PCL nanofibers by introducing 2-aminoethyl methacrylate (AEMA) through gamma-irradiation and subsequently immobilized heparin onto the nanofibers using the EDC/NHS reaction. The SEM images show that there is almost no change in the morphology of nanofibers after radiation grafting of AEMA and heparin-immobilization onto PCL nanofibers. The surface properties of the scaffolds were characterized by ATR-FTIR, XPS, and fluorescamine staining in order to confirm the successful grafting of AEMA onto the PCL nanofibers. Immobilization of heparin was also confirmed by the amide I (1650 cm(-1)) and amide II group (1550 cm(-1)) from ATR-FTIR. The amounts of heparin were drastically increased on the AEMA-PCL nanofibers as revealed by TBO assay. The initial cell viability of hMSCs was significantly increased on the AEMA grafted nanofibers but grew slowly on heparin-immobilized nanofibers. The cumulative release of bone morphogenetic protein-2 (BMP-2) was slow and continuous onto the heparin-immobilized nanofibers (18.13 +/- 3.87 mu g mL(-1)) compared to PCL nanofibers (20.25 +/- 1.45 mu g mL(-1)). Therefore, heparin-immobilized nanofibers may be a good tool for tissue engineering applications using radiation technology.

A monolayer of endothelial cells (ECs) aligned along the direction of blood flow plays crucial roles in the regulation of anti-thrombogenic and pro-inflammatory reactions in the blood vessel wall. Thus, many researchers have attempted to mimic the aligned structure of ECs in vascular grafts or tissue-engineered blood vessels. In the present study, we fabricated micro-groove patterned nanofibers using a femtosecond laser ablation technique to recapitulate the densely organized anisotropic architecture of the endothelial layer. Femtosecond laser ablation enabled us to generate high-resolution groove patterns (10 μm width) with 20 or 80 μm gaps on randomly oriented electrospun nanofibers. The patterned nanofibers exhibited anisotropic (transverse: 101.1 ± 4.0° and longitudinal: 123.5 ± 9.4°) water contact angles; however, the mechanical properties were consistent in both directions. The micropatterned nanofibers modulated the aligned structure or aspect ratio (20 μm: 0.23 ± 0.11 and 80 μm: 0.42 ± 0.18) of ECs along the pattern direction. In particular, the engineered aligned endothelial layer was effective in eliciting an anti-inflammatory response (approximately 50% greater than that of random or aligned nanofibers), thereby effectively preventing monocyte adhesion following activation by TNF-α treatment. Therefore, micropatterning by laser ablation can be utilized to generate high-resolution microgrooves on various substrates, thereby providing fundamental platforms for vascular tissue engineering.

Metronidazole (MD) is known as a periodontitis medicine and has been widely used in antibiotics for resistance to anaerobic bacteria, periodontal disease, and other threats. To treat diseases, drug delivery carriers are needed with a high bioadhesive property and enhanced drug penetration. Poly (acrylic acid) (PAA) hydrogel films have a good bioadhesive property and are able to localize the absorption site and increase the drug residence time. In this study, we fabricated a MD loaded PAA hydrogel with different MD content (0.1, 0.25, 0.5, and 1 wt%) using varying doses (25, 50, and 75 kGy) and the radiation doses (25, 50, or 75 kGy) in a one-step gamma-ray irradiation process. The chemical and physical structure were determined through a Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, gel content, and compressive strength. In addition, MD loaded PAA hydrogels were performed to MD release behaviors and cytotoxicity. Finally, we conducted antibacterial activity to demonstrate the prevention of growth of bacteria as a therapeutic dressing. The basic chemical structure analysis of MD was changed greatly at radiation doses of 50 and 75 kGy due to degradation by gamma-ray irradiation. However, when the absorbed dose was 25 kGy, the chemical structure analysis of MD did not change significantly, and the gel content and compressive strength of MD/PAA hydrogel were approximately 80% and 130 kPa, respectively. The MD/PAA hydrogels exhibited no cytotoxicity and good antibacterial activity against Escherichia coli, Staphylococcus aureus, and Streptococcus mutans. These results provide good evidence that MD/PAA hydrogel prepared by gamma-ray irradiation has potential as a competitive candidate for the therapeutic dressing.

Achilles tendinitis caused by overuse, aging, or gradual wear induces pain, swelling, and stiffness of Achilles tendon and leads to tendon rupture. This study was performed to investigate the suppression of inflammation responses in interleukin-1β- (IL-1β-) stimulated tenocytes in vitro and the suppression of the progression of Achilles tendinitis-induced rat models in vivo using dexamethasone-containing porous microspheres (DEX/PMSs) for a sustained intratendinous DEX delivery. DEX from DEX/PMSs showed the sustained release of DEX. Treatment of IL-1β-stimulated tenocytes with DEX/PMSs suppressed the mRNA levels for COX-2, IL-1β, IL-6, and TNF-α. The intratendinous injection of DEX/PMSs into Achilles tendinitis rats both decreased the mRNA levels for these cytokines and increased mRNA levels for anti-inflammatory cytokines IL-4 and IL-10 in tendon tissues. Furthermore, DEX/PMSs effectively prevented tendon degeneration by enhancing the collagen content and biomechanical properties. Our findings suggest that DEX/PMSs show great potential as a sustained intratendinous delivery system for ameliorating inflammation responses as well as tendon degeneration in Achilles tendinitis.

Purpose Patients with diabetes mellitus have an elevated risk of atrial fibrillation (AF). However, whether insulin resistance may elevate risk of AF incidence in non-diabetic is inconsistent. The aim of our study was to verify the association between insulin resistance and incidence of AF in non-diabetics. Methods We evaluated population-based cohorts embedded in the Korean Genome Epidemiology Study. Insulin resistance was expressed as Homeostasis Model Assessment for Insulin resistance (HOMA-IR). Baseline data including HOMA-IR and electrocardiography (ECG) were obtained at 2001. Subsequent biennial ECG was performed for identification of AF until 2016. Results Among the 8220 participants (46.8% male; median age 49 years), 25 participants had AF (0.3%) at baseline and 101 participants developed AF (1.2%) during follow up of 12 years. In multivariate Cox regression analysis, high HOMA-IR (≥1.4) was significantly associated with incident AF compared with low HOMA-IR ( Subgroup analysis Conclusion Based on prospective cohort study, insulin resistance (HOMA-IR) was associated with AF independently of obesity in non-diabetics.

Background Paradoxical beneficial effects of obesity on all-cause and cardiovascular mortality have been reported in multiple cohort studies based on patients with cardiovascular disease as well as general populations. However, the association between the presence of obesity at baseline and the better survival rates could not be directly interpreted into the beneficial effect of gain in obesity or fatness on the mortality, which makes it difficult to provide any recommendation for the management of obesity. Therefore, we investigated the influence of the changes in body fat on all-cause and cardiovascular mortality in a general population. Methods A population-based cohort study has been conducted for 12 years (from 2001 to 2012). A total of 5,259 subjects in whom body compositions using a bio-impedance method were measured at least 2 times during the observational period were included. The causes of death was identified from the nation-wide database in KOSTAT. I20-I82 and R99 in the International Classification of Disease-10 codes were defined as a cardiovascular death. The subjects were evenly divided into 3 groups by the percentages of the changes in body fat (Δ%BF; decreased [Δ%BF Results The age was 51.2±8.5 years and 51.6% was male. Median observation duration was 163 (the interquartile range: 157–168) months. The all-cause death and cardiovascular death occurred most frequently in the decreased Δ%BF group and least frequent in the highly increased Δ%BF group in both unweighted and weighted cohort. Multivariate Cox proportional hazard models showed that the risk of all-cause death was lower in the increased and highly increased Δ%BF groups (hazard ratio [HR] 0.61 [0.47–0.80] and 0.24 [0.17–0.34], respectively) and the risk of cardiovascular death was lower in the highly increased Δ%BF group (HR 0.20 [0.08–0.48]), compared to those in the decreased Δ%BF group after adjustment for all covariates including physical activities and the changes in muscle mass. The risk of all-cause death and cardiovascular death linearly decreased with increasing Δ%BF (HR 0.72 [0.67–0.77] and 0.70 [0.60–0.82], respectively). Conclusion The increase in body fat is associated with a lower risk of all-cause death and cardiovascular death in a middle-age general population, independently with physical activities and the changes in muscle mass.

Herein, carboxymethyl chitosan and poly(vinylpyrrolidone) based hydrogels were synthesized by electron beam irradiation with dose variations (15 kGy, 30 kGy, and 45 kGy) for drug delivery applications. Irradiation crosslinked hydrogels were characterized for swellings in different medias, chemical, thermal, cell cytotoxicity, and drug release aspects. Swelling analysis was evaluated in distilled water, buffer, and saline solutions. Fourier transform infrared analysis revealed the establishment of physical interactions and confirmed the presence of functional groups present in the drug carriers. Scanning electron microscopy depicted the porous structure, which is responsible for swelling, drug loading, and release. Cell cytotoxicity assays indicated good cell viability on RAW 264.7 cells and anticancer activity on cancerous AGS cell lines. Cumulative drug release (%) of kanamycin in PBS at pH 7.4 was more than 90 % at 168 h. These drug carriers show promise to be developed as a sustained drug delivery system.

Gradual wear and tear can cause a local inflammatory response in tendons. The trauma and inflammatory reaction eventually impair the biomechanical properties of the tendon. In this study, we prepared lactoferrin-immobilized, heparin-anchored, poly(lactic-co-glycolic acid) nanoparticles (LF/Hep-PLGA NPs) and evaluated their in vitro anti-inflammatory effects on interleukin-1β (IL-1β)-treated tenocytes and in vivo tendon healing effects in a rat model of Achilles tendinitis. Long-term LF-deliverable NPs (LF/Hep-PLGA NPs) remarkably decreased mRNA levels of pro-inflammatory factors [cyclooxygenase-2 (COX-2), IL-1β, matrix metalloproteinase-3 (MMP-3), MMP-13, IL-6, and tumor necrosis factor-α (TNF-α)] and increased mRNA levels of anti-inflammatory cytokines (IL-4 and IL-10) in both IL-1β-treated tenocytes and the Achilles tendons of a collagenase-induced Achilles tendinitis rat model. Interestingly, anti-inflammatory LF/Hep-PLGA NPs greatly enhanced collagen content, mRNA levels of tenogenic markers [collagen type I (COL1A1), decorin (DCN), tenascin-C (TNC)], and biomechanical properties such as tendon stiffness and tensile strength. These results suggest that anti-inflammatory LF/Hep-PLGA NPs are effective at restoring tendons in Achilles tendinitis.

Conducting polymer (CP)-based hydrogels exhibit the behaviors of bending or contraction/relaxation due to electrical stimulation. They are similar in some ways to biological organs and have advantages regarding manipulation and miniaturization. Thus, these hydrogels have attracted considerable interest for biomedical applications. In this study, we prepared PPy/PVP hydrogel with different concentrations and content through polymerization and cross-linking induced by gamma-ray irradiation at 25 kGy to optimize the mechanical properties of the resulting PPy/PVP hydrogel. Optimization of the PPy/PVP hydrogel was confirmed by characterization using scanning electron microscopy, gel fraction, swelling ratio, and Fourier transform infrared spectroscopy. In addition, we assessed live-cell viability using live/dead assay and CCK-8 assay, and found good cell viability regardless of the concentration and content of Py/pTS. The conductivity of PPy/PVP hydrogel was at least 13 mS/cm. The mechanical properties of PPy/PVP hydrogel are important factors in their application for biomaterials. It was found that 0.15PPy/PVP20 (51.96 &plusmn, 6.12 kPa) exhibited better compressive strength than the other samples for use in CP-based hydrogels. Therefore, it was concluded that gamma rays can be used to optimize PPy/PVP hydrogel and that biomedical applications of CP-based hydrogels will be possible.

Poly(acrylic acid) (PAAc) hydrogels possess good bioadhesive properties and allow enhanced penetration of drugs. In addition, it is possible to localize the absorption site of the drug in the hydrogel and increase the drug residence time. As opposed to other cross-linking processes radiation-induced polymer cross-linking can be easily and rapidly carried out without the use of cross-linking agents and other chemical additives. In this study, we fabricated metronidazole (MD) containing PAAc hydrogel (MD/PAAc) with different MD contents (0.1, 0.25, 0.5 wt%) using varying radiation doses (25, 50, 75 kGy) by gamma-irradiation. The physical and thermal properties were determined by gel content analysis, swelling ratio measurements, compressive strength measurements, differential scanning calorimetery, and thermogravimetric analysis. The properties of the hydrogel degraded due to the crystalline nature of MD. The properties of the hydrogel degraded due to the crystalline nature of MD. Cumulative release observed after 50 min in the case of 0.5MD/PAAc and 0.1MD/PAAc was 50% and 10%, respectively. Our findings suggest that MD/PAAc could be a suitable drug delivery carrier for use with radiation-based techniques.

Regeneration of healthy endothelium onto vascular graft materials is imperative for prevention of intimal hyperplasia and thrombogenesis. In this study, we investigated the effect of collagen type IV (COL-IV) immobilized onto electrospun nanofibers on modulation of endothelial cell (EC) function, as a potential signal to rapid endothelialization of vascular grafts. COL-IV is assembled in basement membrane underneath intimal layer and regulates morphogenesis of blood vessels. For immobilization of COL-IV, poly(l-lactic acid) (PLLA) nanofibers (PL) were prepared as a model vascular graft substrate, onto which acrylic acid (AAc) was then grafted by using gamma-ray irradiation. AAc graft was dependent on irradiation doses and AAc concentrations, which allowed us to select the condition of 5% (v/v) AAc and 10 kGy for further conjugation of COL-IV. COL-IV immobilization was proportionally controlled as a function of its concentration. Atomic force microscope (AFM) analysis qualitatively supported immobilization of COL-IV, demonstrating increase in root mean square roughness of the PL from 665.37 ± 13.20 nm to 1440.74 ± 33.24. However, the Young's modulus of nanofibers was retained as approximately 1 MPa, regardless of surface modification. The number of ECs attached on the nanofibers with immobilized COL-IV was significantly increased by 5 times (1052 ± 138 cells/mm(2)) from pristine PL (234 ± 41 cells/mm(2)). In addition, the effect of immobilized COL-IV was profound for enhancing proliferation and up-regulation of markers implicated in rapid endothelialization. Collectively, our results suggest that COL-IV immobilized onto electrospun PLLA nanofibers may serve as a promising instructive cue used in vascular graft materials.

The goal of this study was to develop a novel hydroxyapatite (HA) coated bacterial cellulose (BC) scaffold for bone tissue regeneration. HA-coated BC was prepared by immersing in 30 mL of 5× simulated body fluid at 37°C for 12 h. The resulting HA-coated BC scaffolds were characterized by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATRFTIR) spectroscopy, and thermal gravimetric analysis (TGA). HA spherical globules were newly formed on the surface of the BC, and a fibrous network of BC scaffolds still maintained their dimensions for cell adhesion and proliferation. ATR-FTIR spectroscopy analysis showed bands assigned to specific signals for phosphate and carbonate ions from HA. HA-coated BC scaffolds of thermal gravimetric analysis presented residue of around 25%. The ability for bone regeneration of HA-coated BC scaffolds was evaluated using a rat calvarial defect model for 4 and 8 weeks. After implantation, both BC and HAcoated BC scaffolds showed new bone formation derived from existing bone, and found new bone even inside the scaffold. Furthermore, a new bone area was signigicantly increased in the HA-coated BC scaffolds compared with those from BC scaffolds, and bone-like materials were frequently found in HA-coated BC scaffolds. Therefore, the HA-coated BC scaffolds can be used as an effective tool for bone tissue regeneration.

Bacterial cellulose (BC) has been shown to have a high-burst pressure, high-water contact, and ultrafine highly nanofibrous structure similar with that in a natural extracellular matrix (ECM). In the present study, we developed a BC-based functional scaffold for tissue engineering using radiation technology. BC was generated by Gluconacetobacter hansenii TL-2C. Acrylic acid (AAc) was grafted onto BC surfaces under aqueous conditions using gamma-ray irradiation. The characterization of the scaffold was performed by scanning electron microscopy, ATR-FTIR spectroscopy, a toluidine blue O assay, and 2,4,6,-trinitro-benzensulfonic acid assay. AAc was grafted on the BC under gamma-ray irradiation. Gelatin was chemically conjugated on the AAc-BC scaffolds through EDC chemistry. The morphology of the modified BC nanofibers did not change, while representative features of AAc and gelatin were maintained. The adhesion and spreading of human mesenchymal stem cells was improved on the gelatin-AAc-BC nanofibers compared to unmodified BC and AAc-BC nanofibers. Our results suggest that gelatin-immobilized BC nanofiber scaffolds can be a promising way to fabricate three-dimentional, nanofibrous scaffolds that accelerate cell behavior for biomedical applications.

In this work, we present a biomimetic fibrous scaffold containing two biomolecules. A biocompatible poly(L-lactide-co-e-caprolactone) mesh was fabricated by an electrospinning method, and then acrylic acid was grafted on the mesh to introduce a carboxyl group through γ-ray irradiation. Subsequently, the epidermal growth factor (EGF) and gelatin were coupled to the mesh through the EDC reaction. The modified mesh presents a consistent fibre diameter (874.4 ± 178.5 nm), with carboxyl groups (1.3 mM). EGF (171.7 ng mg−1 mesh) and gelatin (67.2 ± 30.5 μg mg−1 mesh) were successfully coupled on the mesh. The coupled EGF and gelatin promoted the cell viability 1.5-times higher than that from a non-modified mesh. In particular, the EGF on the meshes independently allowed hMSC to present a 3-times greater involucrin expression and enabled improved procollagen secretion, implying trans-differentiation of hMSC to keratinocyte-like cells. Therefore, the co-immobilization strategy of biomolecules using radiation technology may be an alternative tool for tissue engineering applications.

A buccal delivery system provides a much milder environment for drug delivery compared to an oral delivery which presents a hostile environment for drugs, especially proteins and polypeptides, owing to acid hydrolysis. Local delivery in an oral cavity has particular applications in the treatment of toothaches, periodontal disease, and bacterial infections. Poly(acrylic acid) (PAA)-based hydrogels prepared using a chemical initiator have been attempted for a mucoadhesive system owing to their flexibility and excellent bioadhesion. In this experiment, PAA and polyethylene glycol (PEG) were selected to prepare using a radiation process a bioadhesive hydrogel for adhesion to mucosal surfaces. PAA and PEG were dissolved in purified water to prepare a homogeneous PAA/PEG solution, and the solution was then irradiated using an electron beam at dose up to 70 kGy to make the hydrogels. Their physical properties, such as gel percent, swelling percent, and adhesive strength to mucosal surfaces, were investigated. In this experiment, various amounts of PEG were incorporated into the PAA to enhance the mucoadhesive property of the hydrogels. The effect of the molecular weight of PEG on the mucoadhesion was also examined.

Hyaluronic acid (HA)/chondroitin sulfate (CS)/poly(acrylic acid) (PAAc) hydrogel systems were synthesized by gamma-ray irradiation without the use of additional initiators or crosslinking agents to achieve a biocompatible hydrogel system for skin tissue engineering. HA and CS derivatives with polymerizable residues were synthesized. Then, the hydrogels composed of glycosaminoglycans, HA, CS, and a synthetic ionic polymer, PAAc, were prepared using gamma-ray irradiation through simultaneous free radical copolymerization and crosslinking. The physicochemical properties of the HA/CS/PAAc hydrogels having various compositions were investigated to evaluate their feasibility as artificial skin substitutes. The gel fractions of the HA/CS/PAAc hydrogels increased in absorbed doses up to 15 kGy, and they exhibited 91–93% gel fractions under 15 kGy radiation. All of the HA/CS/PAAc hydrogels exhibited relatively high water contents of over 90% and reached an equilibrium swelling state within 24 h. The enzymatic degradation kinetics of the HA/CS/PAAc hydrogels depended on both the concentration of the hyaluronidase solution and the ratio of HA/CS/PAAc. The in vitro drug release profiles of the HA/CS/PAAc hydrogels were significantly influenced by the interaction between the ionic groups in the hydrogels and the ionic drug molecules as well as the swelling of the hydrogels. From the cytotoxicity results of human keratinocyte (HaCaT) cells cultured with extracts of the HA/CS/PAAc hydrogels, all of the HA/CS/PAAc hydrogel samples tested showed relatively high cell viabilities of more than 82%, and did not induce any significant adverse effects on cell viability.

This study explored a novel strategy to restore the vocal gap by using cross-linkedβ-glucan hydrogel byγ-irradiation. An aqueous solution of 5 wt%β-glucan was prepared and cross-linked using60Coγirradiation. Ten nude mice were injected with 0.8 mL of irradiatedβ-glucan on the left back and the same volume of nonirradiatedβ-glucan on the right back for comparison. The mice were sacrificed at 1 and 2 weeks after injection and histological evaluations were performed. Irradiatedβ-glucan demonstrated a significantly larger volume than nonirradiatedβ-glucan in the back of nude mice with less inflammatory reaction. After unilateral recurrent laryngeal nerve section in New Zealand White rabbits, irradiated and nonirradiatedβ-glucan were injected into paralyzed vocal folds. Irradiatedβ-glucan remained at the paralyzed vocal fold without definite inflammatory signs on endoscopy. High-speed recordings of vocal fold vibration showed decreased vocal gap in irradiated group compared to nonirradiated group. Histologically, the laryngeal epithelium and lamina propria remained intact, without inflammatory cell infiltration. Our newly developed injection material, irradiatedβ-glucan, showed excellent biocompatibility and remained longer than nonirradiatedβ-glucanin vivo, suggesting irradiated hydrogels as a new therapeutic approach that may be useful for the long-term treatment of vocal fold palsy.

Conductive polymers, including polypyrrole (PPy), have been extensively explored to fabricate electrically conductive biomaterials for bioelectrodes and tissue engineering scaffolds. For their in vivo uses, a sterilization method without severe impairment of original material properties and performance is necessary. Gamma-ray radiation has been commonly applied for sterilization of medical products because of its simple and uniform sterilization without heat generation. Herein we describe the first study on gamma-ray sterilization of PPy bioelectrodes and its effects on their characteristics. We irradiated PPy bioelectrodes with different doses (0–75 kGy) of gamma-rays. Gamma-ray irradiation of the PPy (γ-PPy) increased the oxygenation and hydrophilicity of the surfaces. Interestingly, gamma-ray irradiation did not alter the electrical impedances and conductivities of the PPy substrates. Additionally, γ-PPy prepared with various dopants (e.g., para-toluene sulfonate, polystyrene sulfonate, and chlorine) showed the electrochemical properties similar to the non-irradiated control. Gamma-ray irradiation at doses of ≥15 kGy was required for effective sterilization as evidenced by complete eradication of gram positive and negative bacteria. γ-PPy substrates also showed cytocompatibility similar to untreated control PPy, indicating no substantial alteration of cytocompatibility. In conclusion, gamma ray sterilization is a viable method of sterilization of conducting polymer-based biomaterials for biomedical applications.

Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes) were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05). Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; %) than 300k EI-BCMs at 8 weeks after implantation (p < 0.05). Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

β-Glucan can provide excellent environment to apply to drug carrier due to its immunological and anti-inflammatory effect. Minocycline hydrochloride (MH) has excellent oral bioavailability pharmacological properties. Specifically, MH is effectively absorbed into the gingiva for periodontal disease treatment. In this study, we attempt to develop MH loaded β-glucan hydrogel for periodontal disease treatment through radiation-crosslinking technique. In addition, MH loaded β-glucan hydrogels were tested for their cytotoxicity and antibacterial activity. Finally, we conducted an in vivo study to demonstrate the potential to prevent the invasion of bacteria to treat periodontal disease. The gel content and compressive strength of the β-glucan hydrogels increased as the β-glucan content and the absorbed dose (up to 7 kGy) increased. For a radiation dose of 7 kGy, the gelation and the compressive strength of a 6 wt% β-glucan hydrogel were approximately 92% and 270 kPa, respectively. As a drug, MH was consistently released from β-glucan hydrogels, reaching 80% at approximately 90 min. Furthermore, the MH loaded β-glucan hydrogels showed no cytotoxicity. The MH loaded β-glucan hydrogels exhibited good antibacterial activity against Porphyromonas gingivalis. In addition, MH loaded β-glucan hydrogel demonstrated the potential of a good capability to prevent the invasion of bacteria and to treat wounds.

This study introduces the effect of the thickness of a bacterial cellulose membrane by comparing the bone regeneration effect on rat skulls when using a collagen membrane and different thicknesses of resorbable bacterial cellulose membranes for guided bone regeneration. Barrier membranes of 0.10 mm, 0.15 mm, and 0.20 mm in thickness were made using bacterial cellulose produced as microbial fermentation metabolites. Mechanical strength was investigated, and new bone formation was evaluated through animal experimental studies. Experimental animals were sacrificed after having 2 weeks and 8 weeks of recovery, and specimens were processed for histologic and histomorphometric analyses measuring the area of bone regeneration (%) using an image analysis program. In 2 weeks, bone-like materials and fibrous connective tissues were observed in histologic analysis. In 8 weeks, all experimental groups showed the arrangement of osteoblasts surrounding the supporting body on the margin and center of the bone defect region. However, the amount of new bone formation was significantly higher (p < 0.05) in bacterial cellulose membrane with 0.10 mm in thickness compared to the other experimental groups. Within the limitations of this study, a bacterial cellulose membrane with 0.10 mm thickness induced the most effective bone regeneration.

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study investigated the various behaviors and characteristics of chestnut honey-impregnated carboxymethyl cellulose sodium hydrogel paste (CH–CMC) as a therapeutic dressing, such as its moist retention, antibacterial activity for inhibiting the growth of Staphylococcus aureus and Escherichia coli, and the rate of wound healing in db/db mice. The results provide good evidence, suggesting that CH–CMC has potential as a competitive candidate for diabetic ulcer wound healing.

There is a growing interest in bone graft materials for enhancing bone formation. We have focused on bone xenograft using animal by-products. Among animal by-products, the duck beak was specifically used in this study for manufacture of bone graft particles. Harvested duck-beak bone was defatted, deproteinized, and then heat-treated at 350ΰC. Subsequently, it was ground to ≤ 53 μm in a ceramic ball mill and irradiated with gamma rays at radiation doses of 0, 15, 20, 25, and 40 kGy. =Field emission scanning electron microscope (FE-SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and the MTT assay were performed to investigate the effects of gamma-ray irradiation on the properties of duck-beak bone particles. Surface morphology of duck-beak bone particles by FE-SEM showed that bone particles had various sizes and similar surfaces between the 0, 15, 20, 25, and 40 kGy groups. The ATR-FTIR spectrum of all groups showed the characteristic peaks of PO43− and CO32− functional groups. Weight losses were observed and there was no significant difference in the curves depending on the radiation doses, by TGA analyses. The viabilities of human mesenchymal stem cells were 90–100% in all groups in the MTT assay. Based on our results, sterilization by gamma-ray irradiation < 40 kGy had no effect on the physical and surface properties of duck-beak bone particles. Therefore, this study showed that gamma-ray irradiation can be effectively used for the sterilization of duck-beak bone derived xenografts.

Alginate, a linear un-branched polysaccharide derived from seaweed has shown great potential as a cell scaffold for the regeneration of many tissues. However, alginate is not naturally enzymatically degraded in ionically crossliked alginate htdrogels exhibit a remarkably slow degradation rate, which is typically months to years for their complete removal from injection site. The ionizing irradiation degrades polysaccharides through the free radical-induced scission of glycosidic bonds of alginate. In this work, alginate/PEO nanofiber was irradiated 60Co γ-rays in the dose range of 50-300 kGy. This approach offers control over the degradation rate by varying the gamma-irradiation dose degree, as increasing the gamma-irradiation dose degree can increase the vulnerability of alginate nanofibers to hydrolysis under in vitro condition. And, the ability of electrospun a cell adhesive peptide Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) modified alginate and unmodified alginate nanofibrous scaffolds to support human mesenchymal stem cell (hMSCs) attachment and spreading was greatly enhanced on the adhesion ligand-modified compared to unmodified nanofibers, demonstrating the initial promise of this electrospun polysaccharide material with defined nanoscale architecture and cell adhesive properties for tissue regeneration applications.

Over the last decade, bone tissue engineering scaffolds have been advanced owing to the bioceramic incorporation and biomimetic modification. In this report, a dual-functional fibrous scaffold with a bioceramic and biomolecule is developed, and a combined effect of a dual-modification is investigated. Biphasic calcium phosphate (BCP) is incorporated in electrospun poly (L-lactide) scaffolds, and Arg-Gly-Asp (RGD) peptide is then conjugated through the graft polymerization of acrylic acid by γ-ray irradiation. The scaffolds exhibit the intrinsic properties of BCP as well as RGD peptide, and only RGD peptide improves an adhesion and proliferation of the human mesenchymal stem cell. However, alkaline phosphatase activity and calcium formation are synergistically improved by the BCP and RGD peptide indicating that a favorable microenvironment is constructed for bone formation. Therefore, this combination strategy with bioceramic and biomolecule can be a useful tool for the bone tissue engineering.

An artificial construct mimicking the intrinsic properties of the natural extracellular matrix in bones has been considered an ideal platform for bone tissue engineering, as it can present an appropriate microenvironment and regulate cell behaviours. In this report, we introduce biodegradable composite scaffolds consisting of polycaprolactone (PCL) and biphasic calcium phosphate (BCP). The scaffolds were fabricated by a salt-leaching process, and the ability of the scaffolds to facilitate osteogenic differentiation was investigated using human mesenchymal stem cells (hMSCs). The scaffolds had an inter-connected porous structure with quadrilateral pores of approximately 200 ∼ 500 μm in width. The mechanical properties of the scaffolds changed as the BCP content was increased in the starting mixture. In the hMSC experiment, although we found that hMSCs adhered to the surface, as well as the inside, of the scaffolds, the incorporated BCP did not increase the proliferation of the hMSCs over 7 days in culture. Interestingly, the alkaline phosphatase (ALP) activity was 4 times higher on the PCL/BCP composite scaffold (0.12 ± 0.03 nmol/min/μg protein) thanon the PCL scaffold (0.03 ± 0.01 nmol/min/μg protein), suggesting that BCP can aid in generating a local environment that promotes bone regeneration. Therefore, a strategy combining polymers and ceramics can be considered a useful platform for bone tissue engineering.

One of the interesting strategies for developing the artificial blood vessels is to generate multi-layered scaffolds for mimicking the structure of native blood vessels such as the intima, media, and adventitia. In this study, we prepared dual-layered poly(L-lactide-co-ɛ-caprolactone) (PLCL) scaffolds with micro- and nanofibers as a basic construct of the vessel using electrospinning methods, which was functionalized using a gelatin through acrylic acid (AAc) grafting by γ-ray irradiation. Based on the microfibrous platform (fiber diameter 5 μm), the thickness of the nanofibrous layer (fiber diameter 700 nm) was controlled from 1.1 ± 0.8 to 32.2 ± 1.7 μm, and the mechanical property of the scaffolds was almost maintained despite the increase in thickness of the nanofibrous layer. The successful AAc graft by γ-ray irradiation could allow the gelatin immobilization on the scaffolds. The proliferation of smooth muscle cells (SMC) on the scaffolds toward a microfibrous layer was approximately 1.3-times greater than in the other groups, and the infiltration was significantly increased, presenting a wide cell distribution in the cross-section. In addition, human umbilical vein endothelial cell (HUVEC) adhesion toward nanofibrous layer was well-managed over the entire surface, and the accelerated proliferation was observed on the gelatin-functionalized scaffolds presenting the well-organized gap-junctions. Therefore, our biomimetic dual-layered scaffolds may be the alternative tools for replacing the damaged blood vessels.

Gamma-ray irradiation of novel hydrogels was used to develop a biocompatible hydrogel system for skin tissue engineering. These novel hydrogels are composed of natural polymers including hyaluronic acid (HA) and chondroitin sulfate (CS), and the synthetic polymer, poly(vinyl alcohol) (PVA). The γ-ray irradiation method has advantages, such as relatively simple manipulation without need of any extra reagents for polymerization and cross-linking. We synthesized HA and CS derivatives with polymerizable residues. The HA/CS/PVA hydrogels with various compositions were prepared by using γ-ray irradiation technique and their physicochemical properties were investigated to evaluate the feasibility of their use as artificial skin substitutes. HA/CS/PVA hydrogels showed an 85-88% degree of gelation under 15 kGy radiation. All HA/CS/PVA hydrogels exhibited more than 90% water content and reached an equilibrium swelling state within 24h. Hydrogels with higher concentrations of hyaluronidase solution and HA/CS content had proportionally higher enzymatic degradation rates. The drug release behaviors from HA/CS/PVA hydrogels were influenced by the composition of the hydrogel and drug properties. Exposure of human keratinocyte (HaCaT) culture to the extracts of HA/CS/PVA hydrogels did not significantly affect the cell viability. All HaCaT cell cultures exposed to the extracts of HA/CS/PVA hydrogels exhibited greater than 92% cell viability. The HaCaT growth in HA/CS/PVA hydrogels gradually increased as a function of culture time. After 7 days, the HaCaT cells in all HA/CA/PVA hydrogels exhibited more than 80% viability compared to the control group HaCaT culture on a culture plate.

Honey has been used in wound care for thousands of years. The major advantage of honey in wound care is the high osmotic activity, which accelerates the debridement of necrotic tissue and procures an antibacterial effect. It has been reported that the ancient Greeks and Romans used honey as a topical antiseptic for sores and skin ulcers. The aims of this study were to evaluate the antibacterial activities and the healing effect for diabetic ulcers from carboxymethyl cellulose (CMC) hydrogel involving honey. Carboxymethyl cellulose (CMC) and honey were dissolved in deionized (DI) water, and then irradiated by a gamma-ray to make a honey hydrogel dressing. The physical properties such as gelation and swelling were examined to evaluate the hydrogel for wound dressing. The antibacterial activities were investigated in detail against the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. Antibacterial tests indicated that honey hydrogel dressings have a good antibacterial activity. Female db/db mice (weight between 18 and 24 g, aged 5 weeks) were given an in vivo wound healing assessment. The wound dressing was changed every 2 days, and the rate of wound contraction and microscopic observations were observed. The honey hydrogel dressings displayed a prominent healing effect for diabetic ulcers.