Search

Biogenic collagen membranes have been widely used as soft tissue barriers in guided bone regeneration (GBR) and guided tissue regeneration (GTR). Nevertheless, their clinical performance remains unsatisfactory because of their low mechanical strength and fast degradation rate in vivo. Although cross-linking with chemical agents is effective and reliable for prolonging the degradation time of collagen membranes, some adverse effects including potential cytotoxicity and undesirable tissue integration have been observed during this process. As a fundamental nutritional trace element, zinc plays an active role in promoting the growth of cells and regulating the degradation of the collagen matrix. Herein, a biogenic collagen membrane was cross-linked with glutaraldehyde-alendronate to prolong its degradation time. The physiochemical and biological properties were enhanced by the incorporation of zinc-doped nanohydroxyapatite (nZnHA), with the native structure of collagen preserved. Specifically, the cross-linking combined with the incorporation of 1% and 2% nZnHA seemed to endow the membrane with the most appropriate biocompatibility and tissue integration capability among the cross-linked membranes, as well as offering a degradation period of six weeks in a rat subcutaneous model. Thus, improving the clinical performance of biogenic collagen membranes by cross-linking together with the incorporation of nZnHA is a promising strategy for the improvement of biogenic collagen membranes. STATEMENT OF SIGNIFICANCE: The significance of this research includes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

Implant-associated infections is one of the most challenging post-operative complications in bone-related implantations. To tackle this clinical issue, we developed a low-cost and durable surface coating for medical grade titanium implants that uses positively charged silane molecules. The in vitro antimicrobial tests revealed that the titanium surface coated with (3-aminopropyl) triethoxysilane, which has the appropriate length of hydrophobic alkyl chain and positive charged amino group, suppressed more than 90% of the initial bacterial adhesion of S. aureus, P. aeruginosa, and E. coli after 30 min of incubation. In terms of growth inhibitory rate, the treated surface was able to reduce 75.7% ± 11.9% of bacterial growth after a 24-hour culturing, thereby exhibiting superior anti-biofilm formation in the late stage. When implanted into the rat model infected by S. aureus, the treated surface eliminated the implant-associated infection through the mechanism of inhibition of bacterial adhesion on the implant surface. Additionally, the treated surface was highly compatible with mammalian cells. In general, our design demonstrated its potential for human clinical trials as a low-cost and effective antibacterial strategy to minimize post-operative implant-related bacterial infection., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Cutaneous wounds, especially chronic wounds, remain clinical challenges, and this is partially due to the complex healing process composed of four overlapping but distinct stages including hemostasis, inflammation, proliferation and remodeling. Therefore, wound dressings with spatially designed structures which can temporally regulate certain bioactive components to function at specific healing stages might be able to accelerate the healing process. In this study, nanobioglass incorporated chitosan-PVA (polyvinyl alcohol) trilayer nanofibrous membrane (nBG-TFM) was fabricated via sequential electrospinning. This membrane exhibited excellent biocompatibility, antibacterial activity and regeneration promotion effect. Furthermore, spatially designed structure optimized functions of each component and provided more suitable microenvironment as compared with uniform membrane. Rat full-thickness skin defects model and mice diabetic chronic wound model showed that nBG-TFM could achieve significantly accelerated and enhanced healing, in terms of complete re-epithelialization, improved collagen alignment and formation of skin appendages. It was revealed that nBG-TFM functioned through upregulating growth factors including VEGF and TGF-β. Meanwhile inflammatory cytokines such as TNF-α and IL-1β were downregulated. The technology presented in this study shed new light on designing functional wound dressings which can promote healing of chronic wounds., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Magnesium biometals exhibit great potentials for orthopeadic applications owing to their biodegradability, bioactive effects and satisfactory mechanical properties. However, rapid corrosion of Mg implants in vivo combined with large amount of hydrogen gas evolution is harmful to bone healing process which seriously confines their clinical applications. Enlightened by the superior biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we employ the Ti and O dual plasma ion immersion implantation (PIII) technique to construct a multifunctional TiO 2 based nano-layer on ZK60 magnesium substrates for enhanced corrosion resistance, osteoconductivity and antimicrobial activity. The constructed nano-layer (TiO 2 /MgO) can effectively suppress degradation rate of ZK60 substrates in vitro and still maintain 94% implant volume after post-surgery eight weeks. In animal study, a large amount of bony tissue with increased bone mineral density and trabecular thickness is formed around the PIII treated group in post-operation eight weeks. Moreover, the newly formed bone in the PIII treated group is well mineralized and its mechanical property almost restores to the level of that of surrounding mature bone. Surprisingly, a remarkable killing ratio of 99.31% against S. aureus can be found on the PIII treated sample under ultra-violet (UV) irradiation which mainly attributes to the oxidative stress induced by the reactive oxygen species (ROS). We believe that this multifunctional TiO 2 based nano-layer not only controls the degradation of magnesium implant, but also regulates its implant-to-bone integration effectively. STATEMENT OF SIGNIFICANCE: Rapid corrosion of magnesium implants is the major issue for orthopaedic applications. Inspired by the biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we construct a multifunctional TiO 2 /MgO nanolayer on magnesium substrates to simultaneously achieve superior corrosion resistance, satisfactory osteoconductivity in rat intramedullary bone defect model and excellent antimicrobial activity against S. aureus under UV irradiation. The current findings suggest that the specific TiO 2 /MgO nano-layer on magnesium surface can achieve the three objectives aforementioned and we believe this study can demonstrate the potential of biodegradable metals for future clinical applications., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Ocean acidification (OA) is well-known for impairing marine calcification; however, the end response of several essential species to this perturbation remains unknown. Decreased pH and saturation levels (Ω) of minerals under OA is projected to alter shell crystallography and thus to reduce shell mechanical properties. This study examined this hypothesis using a commercially important estuarine oyster Magallana hongkongensis. Although shell damage occurred on the outmost prismatic layer and the undying myostracum at decreased pH 7.6 and 7.3, the major foliated layer was relatively unharmed. Oysters maintained their shell hardness and stiffness through altered crystal unit orientation under pH 7.6 conditions. However, under the undersaturated conditions (Ω Cal  ~ 0.8) at pH 7.3, the realigned crystal units in foliated layer ultimately resulted in less stiff shells which indicated although estuarine oysters are mechanically resistant to unfavorable calcification conditions, extremely low pH condition is still a threat to this essential species., (Copyright © 2018. Published by Elsevier Ltd.)

Bacterial infections and related complications are predominantly responsible for the failure of artificial biomaterials assisted tissue regeneration in clinic. In this work, a hybrid surface system is applied to prolong the drug release duration from dug-loaded titania nanotubes and thus to prevent Ti implants-associated bacterial infections. This feature is endowed by conjugating folic acid (FA) onto the surface of ZnO quantum dots (QDs)-NH 2 via an amidation reaction. Titania nanotubes (TNTs) loaded with vancomycin (Van) are capped by these FA functionalized ZnO (ZnO-FA) QDs that keep stable in normal physiological environments but dissolves to Zn 2+ in the mildly acidic environment after bacterial infections as validated by the drug release profile. The antibacterial ratio of TNTs-Van@ZnO-FA QDs against Staphylococcus aureus is enhanced from 60.8% to 98.8%while this value is only increased from 85.2% to 95.1% for TNTs-Van once the pH value of the environment is decreased from 7.4 to 5.5. This is due to the synergistic effects of Van and Zn 2+ because the gradual dissolution of ZnO-FA caps on TNTs with the decrease of pH value can induce the acceleration of both Van and Zn 2+ release. In addition, this TNTs-Van@ZnO-FA system also exhibits excellent biocompatibility because of the folic acid and sustained release of Zn ions. Hence, this surface system can be potentially used as a promising bioplatform on Ti-based metallic implants to prevent bacterial infection with a long-lasting effect., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Tearing of the rotator cuff commonly occurs as among one of the most frequently experienced tendon disorders. While treatment typically involves surgical repair, failure rates to achieve or sustain healing range from 20 to 90%. The insufficient capacity to recover damaged tendon to heal to the bone, especially at the enthesis, is primarily responsible for the failure rates reported. Various types of biomaterials with special structures have been developed to improve tendon-bone healing and tendon regeneration, and have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects. In this review, we first give a brief introduction of the anatomy of the rotator cuff and then discuss various design strategies to augment rotator cuff repair. Furthermore, we highlight current biomaterials used for repair and their clinical applications as well as the limitations in the literature. We conclude this article with challenges and future directions in designing more advanced biomaterials for augmentation of rotator cuff repair., (Copyright © 2017 Elsevier B.V. All rights reserved.)

To prevent the attachment of bacteria to implant surfaces, the 1D zinc oxide nanowire-coating has been successfully developed on material surfaces by using a custom-made hydrothermal approach. The chemical nature, surface topography and wettability of spike-like 1D ZnO nanowire-coating are comprehensively investigated. The anti-adhesive and antimicrobial properties of 1D nanowire-coating are tested against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by using in vitro live/dead staining and scanning electron microscopy. We find that the adhesion of bacteria can be reduced via the special spike-like topography and that the release of Zn(2+) ions can help suppress the growth of attached bacteria. Furthermore, the antimicrobial effect is also evaluated under in vivo conditions by using a rat model infected with bioluminescent S. aureus. The amount of live bacteria in the rat implanted with a nanowire-coated sample is less than that of the control at various time points. Hence, it is believed that the nanowire-coated material is promising for application in orthopaedic implantation after the long-term animal studies have been completed., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The potential use of osteo-conducive biomaterials in the promotion of bone fracture healing has attracted wide attention. This study investigated if silver nanoparticles (AgNps) could promote the proliferation and osteogenesis of mesenchymal stem cells (MSCs), and improve bone fracture healing. We showed that AgNps promoted MSCs' proliferation and osteogenic differentiation in vitro. Using a mouse femoral facture model, AgNps encapsulated in collagen promoted the formation of fracture callus, and induced early closure of the fracture gap. AgNps may promote the formation of the callus and the subsequent end joining of the fracture bone via multiple routes: (i) chemo-attraction of MSCs and fibroblasts to migrate to the fracture site; (ii) induction of the proliferation of MSCs; (iii) induction of osteogenic differentiation of MSCs via induction/activation of TGF-β/BMP signaling in MSCs. We concluded that AgNps might be beneficial as an adjunct treatment for bone fracture healing clinically., From the Clinical Editor: Silver nanoparticles are widely used in wound management in the clinical setting. In this article, the authors demonstrated a novel application in that these nanoparticles were efficient in promoting osteoblastic differentiation in both in-vitro and in-vivo studies. The findings may provide a new treatment direction for bone fracture in the future., (Copyright © 2015 Elsevier Inc. All rights reserved.)

This study demonstrates a novel method of using silver nanoparticles for Achilles tendon injury healing. In vitro results indicated a stimulatory effect on cell proliferation and collagen synthesis with silver nanoparticles. Biomechanical test on the 42-day post operation Achilles tendon sample exhibited a significant improvement in tensile modulus when compared to the untreated group. Histology suggested that silver nanoparticles promoted cell alignment and proteoglycan synthesis. The collagen deposition was also improved. An alleviation of tumor necrosis factor α, and an increase in fibromodulin and proliferating cell nuclear antigen expression were seen in silver nanoparticles group by immunohistochemistry. This study further corroborates the finding of our previous study that silver nanoparticles help to restore the functionality of injured connective tissues. We believe that the anti-inflammatory nature of silver nanoparticles has an important role in accelerating the healing process and reducing scarring, leading to better functional outcome. From the clinical editor: Tendon healing after surgeries remains a slow and tedious process, typically requiring several weeks of recovery time and gradual introduction of physical therapy. There are no currently utilized methods that could promote tendon healing. In this study, silver nanoparticles are reported to facilitate Achilles tendon repair in a model system, through increased proteoglycan and collagen synthesis, paving the way to potential clinical applications in the future., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Magnesium alloys are potential biodegradable materials and have received increasing attention due to their outstanding biological performance and mechanical properties. However, rapid degradation in the physiological environment and potential toxicity limit clinical applications. Recently, special magnesium-calcium (Mg-Ca) and magnesium-strontium (Mg-Sr) alloys with biocompatible chemical compositions have been reported, but the rapid degradation still does not meet clinical requirements. In order to improve the corrosion resistance, a rough, hydrophobic and ZrO(2)-containing surface film is fabricated on Mg-Ca and Mg-Sr alloys by dual zirconium and oxygen ion implantation. Weight loss measurements and electrochemical corrosion tests show that the corrosion rate of the Mg-Ca and Mg-Sr alloys is reduced appreciably after surface treatment. A systematic investigation of the in vitro cellular response and antibacterial capability of the modified binary magnesium alloys is performed. The amounts of adherent bacteria on the Zr-O-implanted and Zr-implanted samples diminish remarkably compared to the unimplanted control. In addition, significantly enhanced cell adhesion and proliferation are observed from the Zr-O-implanted sample. The results suggest that dual zirconium and oxygen ion implantation, which effectively enhances the corrosion resistance, in vitro biocompatibility and antimicrobial properties of Mg-Ca and Mg-Sr alloys, provides a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys., (Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

A new type of thermosensitive microgels with epoxy functional groups is designed and synthesized for drug delivery. The thermosensitive poly(N-isopropylacrylamide-co-glycidyl methacrylate) (designated as P(NIPAM-co-GMA)) microgels are prepared by an emulsifier-free emulsion polymerization method and the chemical composition of the copolymer is determined by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ((1)H NMR). The lower critical solution temperature (LCST) of the microgels is 32°C based on the transmittance changes at 500 nm monitored by UV/visible spectrophotometry. The hydrodynamic diameter and morphology of the microgel particles are examined by dynamic light scattering (DLS) and scanning electron microscopy (SEM), respectively. The drug release properties determined using 5-FU as the drug model in vitro reveal temperature dependence and low cytotoxicity. The thermosensitive microgels have large potential as targeted anti-cancer drug carriers., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Our previous study has revealed that silver nanoparticles (AgNPs) have potential to promote wound healing by accelerated re-epithelization and enhanced differentiation of fibroblasts. However, the effect of AgNPs on the functionality of repaired skin is unknown. The aim of this study was to explore the tensile properties of healed skin after treatment with AgNPs. Immunohistochemical staining, quantitative assay and scanning electron microscopy (SEM) were used to detect and compare collagen deposition, and the morphology and distribution of collagen fibers. Our results showed that AgNPs improved tensile properties and led to better fibril alignments in repaired skin, with a close resemblance to normal skin. Based on our findings, we concluded that AgNPs were predominantly responsible for regulating deposition of collagen and their use resulted in excellent alignment in the wound healing process. The exact signaling pathway by which AgNPs affect collagen regeneration is yet to be investigated., From the Clinical Editor: The aim of this study was to explore the tensile properties of healed skin after treatment with AgNPs. These nanoparticles improved tensile properties and led to better fibril alignments in repaired skin, with a close resemblance to normal skin. The exact signaling pathway by which AgNPs affect collagen regeneration is yet to be investigated., (Copyright © 2011 Elsevier Inc. All rights reserved.)