Visible light cross-linking and bioactive peptides loaded integrated hydrogel with sequential release to accelerate wound healing complicated by bacterial infection

The effective management of bacterial infections that are resistant to multiple drugs remains a substantial clinical challenge.The eradication of drug-resistant bacteria and subsequent promotion of angiogenesis are imperative for the regeneration of the infected wounds.Here,a novel and facile peptide containing injectable hydrogel with sustained antibacterial and angiogenic capabilities is developed.The antibacterial peptide that consists of 11 residues(CM11,WKLFKKILKVL)is loaded onto acrylate-modified gelatin through charge interactions.A vascular endothelial growth factor mimetic peptide KLT(KLTWQELYQLKYKGI)with a GCG(Gly-Cys-Gly)modification at the N-terminal is covalently coupled through a visible light-induced thiol-ene reaction.In this reaction,the acrylate gelatin undergoes cross-linkage within seconds.Based on the physical/chemical double crosslinking strategy,the bioactive peptides achieve sustained and sequential release.The results show that the hydrogel significantly inhibits methicillin-resistant Staphylococcus aureus(MRSA)growth through the rapid release of CM11 peptides at early stage;it forms obvious growth inhibition zones against pathogenic bacterial strains.Moreover,cell counting kit-8 assay and scratch test confirm that the CM11/KLT-functionalized hydrogels promote cell proliferation and migration through the later release of KLT peptides.In a mouse skin wound infected with self-luminous MRSA,the CM11/KLT-functionalized hydrogels enhance wound healing,with rapidly bacterial infection reduction,lower expression of inflammatory factors,and neovascularization promotion.These results suggest that the rationally designed,sustained and sequential release CM11/KLT-functionalized hydrogels have huge potential in promoting the healing of multi-drug resistant bacterial infected wounds.

Sequentially releasing self-healing hydrogel fabricated with TGFβ3-microspheres and bFGF to facilitate rat alveolar bone defect repair

Resorption and loss of alveolar bone leads to oral dysfunction and loss of natural or implant teeth. Biomimetic delivery of growth factors based on stem cell recruitment and osteogenic differentiation, as the key steps in natural alveolar bone regenerative process, has been an area of intense research in recent years. A mesoporous self-healing hydrogel(DFH) with basic fibroblast growth factor(bFGF) entrapment and transforming growth factor β3(TGFβ3)-loaded chitosan microspheres(CMs) was developed. The formulation was optimized by multiple tests of self-healing, in-bottle inversion, SEM, rheological, swelling rate and in vitro degradation. In vitro tubule formation assays, cell migration assays, and osteogenic differentiation assays confirmed the ability of DFH to promote blood vessels, recruit stem cells, and promote osteogenic differentiation. The optimum DFH formula is 0.05 ml 4ArmPEG-DF(20%) added to 1 ml CsGlu(2%) containing bFGF(80 ng) and TGFβ3-microspheres(5 mg). The results of in vitro release studied by Elisa kit, indicated an 95% release of b FGF in7 d and long-term sustained release of TGFβ3. For alveolar defects rat models, the expression levels of CD29 and CD45, the bone volume fraction, trabecular number, and trabecular thickness of new bone monitored by Micro-CT in DFH treatment groups were significantly higher than others(*P < 0.05, vs Model). HE and Masson staining show the same results.In conclusion, DFH is a design of bionic alveolar remodelling microenvironment, that is in early time microvessels formed by b FGF provide nutritious to recruited endogenous stem cells, then TGFβ3 slowly released speed up the process of new bones formation to common facilitate rat alveolar defect repair. The DFH with higher regenerative efficiency dovetails nicely with great demand due to the requirement of complicated biological processes.

Size-transformable nanoparticles with sequentially triggered drug release and enhanced penetration for anticancer therapy

There are several limitations to the application of nanoparticles in the treatment of cancer,including their low drug loading,poor colloidal stability,insufficient tumor penetration,and uncontrolled release of the drug.Herein,gelatin/laponite(LP)/doxorubicin(GLD)nanoparticles are developed by crosslinking LP with gelatin for doxorubicin delivery.GLD shows high doxorubicin encapsulation efficacy(99%)and strong colloidal stability,as seen from the unchanged size over the past 21 days and reduced protein absorption by 48-fold compared with unmodified laponite/doxorubicin nanoparticles.When gelatin from 115 nm GLD reaches the tumor site,matrix metallopeptidase-2(MMP-2)from the tumor environment breaks it down to release smaller 40 nm LP nanoparticles for effective tumor cell endocytosis.As demonstrated by superior penetration in both in vitro three-dimensional(3D)tumor spheroids(138-fold increase compared to the free drug)and in vivo tumor models.The intracellular low pH and MMP-2 further cause doxorubicin release after endocytosis by tumor cells,leading to a higher inhibitory potential against cancer cells.The improved anticancer effectiveness and strong in vivo biocompatibility of GLD have been confirmed using a mouse tumor-bearing model.MMP-2/pH sequentially triggered anticancer drug delivery is made possible by the logical design of tumor-penetrating GLD,offering a useful method for anticancer therapy.

A programmed surface on polyetheretherketone for sequentially dictating osteoimmunomodulation and bone regeneration to achieve ameliorative osseointegration under osteoporotic conditions

Polyetheretherketone(PEEK)is a desirable alternative to conventional biomedical metals for orthopedic implants due to the excellent mechanical properties.However,the inherent bioinertness of PEEK contributes to inferior osseointegration of PEEK implants,especially under pathological conditions of osteoporosis.Herein,a programmed surface is designed and fabricated on PEEK to dictate osteoimmunomodulation and bone regeneration sequentially.A degradable hybrid coating consisting of poly(lactide-co-glycolide)and alendronate(ALN)loaded nano-hydroxyapatite is deposited on PEEK and then interleukin-4(IL-4)is grafted onto the outer surface of the hybrid coating with the aid of N_(2) plasma immersion ion implantation and subsequent immersion in IL-4 solution.Dominant release of IL-4 together with ALN and Ca^(2+) during the first few days synergistically mitigates the early acute inflammatory reactions and creates an osteoimmunomodulatory microenvironment that facilitates bone regeneration.Afterwards,slow and sustained delivery of ALN and Ca^(2+) in the following weeks boosts osteogenesis and suppresses osteoclastogenesis simultaneously,consequently ameliorating bone-implant osseointegration even under osteoporotic conditions.By taking into account the different phases in bone repair,this strategy of constructing advanced bone implants with sequential functions provides customizable and clinically viable therapy to osteoporotic patients.

Preferentially released miR-122 from cyclodextrin-based star copolymer nanoparticle enhances hepatoma chemotherapy by apoptosis induction and cytotoxics efflux inhibition

Chemotherapy,as one of the most commonly used treatment modalities for cancer therapy,provides limited benefits to hepatoma patients,owing to its inefficient delivery as well as the intrinsic chemo-resistance of hepatoma.Bioinformatic analysis identified the therapeutic role of a liver-specific microRNA-miR-122 for enhancing chemo-therapeutic efficacy in hepatoma.Herein,a cyclodextrin-cored star copolymer nanoparticle system(sCDP/DOX/miR-122)is constructed to co-deliver miR-122 with doxorubicin(DOX)for hepatoma therapy.In this nanosystem,miR-122 is condensed by the outer cationic poly(2-(dimethylamino)ethyl methacrylate)chains of sCDP while DOX is accommodated in the inner hydrophobic cyclodextrin cavities,endowing a sequential release manner of miR-122 and DOX.The preferentially released miR-122 not only directly induces cell apoptosis by down regulation of Bcl-w and enhanced p53 activity,but also increases DOX accumulation through inhibiting cytotoxic efflux transporter expression,which realizes synergistic performance on cell inhibition.Moreover,sCDP/DOX/miR-122 displays remarkably increased anti-tumor efficacy in vivo compared to free DOX and sCDP/DOX alone,indicating its great promising in hepatoma therapy.

Programmed surface on poly(aryl-ether-ether-ketone) initiating immune mediation and fulfilling bone regeneration sequentially

The immune responses are involved in every stage after implantation but the reported immune-regulated materials only work at the beginning without fully considering the different phases of bone healing.Here,poly(aryl-ether-ether-ketone)(PEEK)is coated with a programmed surface,which rapidly releases interleukin-10(IL-10)in the first week and slowly delivers dexamethasone(DEX)up to 4 weeks.Owing to the synergistic effects of IL-10 and DEX,an aptly weak inflammation is triggered within the first week,followed by significant M2 polarization of macrophages and upregulation of the autophagy-related factors.The suitable immunomodulatory activities pave the way for osteogenesis and the steady release of DEX facilitates bone regeneration thereafter.The sequential immune-mediated process is also validated by an 8-week implementation on a rat model.This is the first attempt to construct implants by taking advantage of both immune-mediated modulation and sequential regulation spanning all bone regeneration phases,which provides insights into the fabrication of advanced biomaterials for tissue engineering and immunological therapeutics.

Coaxial-printed small-diameter polyelectrolyte-based tubes with an electrostatic self-assembly of heparin and YIGSR peptide for antithrombogenicity and endothelialization

Low patency ratio of small-diameter vascular grafts remains a major challenge due to the occurrence of thrombosis formation and intimal hyperplasia after transplantation.Although developing the functional coating with release of bioactive molecules on the surface of small-diameter vascular grafts are reported as an effective strategy to improve their patency ratios,it is still difficult for current functional coatings cooperating with spatiotemporal control of bioactive molecules release to mimic the sequential requirements for antithrombogenicity and endothelialization.Herein,on basis of 3D-printed polyelectrolyte-based vascular grafts,a biologically inspired release system with sequential release in spatiotemporal coordination of dual molecules through an electrostatic self-assembly was first described.A series of tubes with tunable diameters were initially fabricated by a coaxial extrusion printing method with customized nozzles,in which a polyelectrolyte ink containing of ε-polylysine and sodium alginate was used.Further,dual bioactive molecules,heparin with negative charges and Tyr-Ile-Gly-Ser-Arg(YIGSR)peptide with positive charges were layer-by-layer assembled onto the surface of these 3D-printed tubes.Due to the electrostatic interaction,the sequential release of heparin and YIGSR was demonstrated and could construct a dynamic microenvironment that was thus conducive to the antithrombogenicity and endothelialization.This study opens a new avenue to fabricate a small-diameter vascular graft with a biologically inspired release system based on electrostatic interaction,revealing a huge potential for development of small-diameter artificial vascular grafts with good patency.