Scaffold composed of porous vancomycin-loaded poly(lactide- co -glycolide) microspheres: A controlled-release drug delivery system with shape-memory effect

4D Printing of Biocompatible Scaffolds via In Situ Photo-crosslinking from Shape Memory Copolyesters

The complexity of surgical treatments for large-area soft tissue injuries makes placing large implants into injury sites challenging. Aliphatic polyesters are often used for scaffold preparation in tissue engineering owing to their excellent biodegradability and biocompatibility. Scaffolds with shape-memory effect (SME) can also avoid large-volume trauma during the implantation. However, the complexity and diversity of diseases require more adaptable and precise processing methods. Four-dimensional (4D) printing, a booming smart material additive manufacturing technology, provides a new opportunity for developing shape memory scaffolds. With the aim of personalized or patient-adaptable soft tissues such as blood vessels, we developed a feasible strategy for fabricating scaffolds with fine architectures using 4D printing crosslinkable shape memory linear copolyesters using fused deposition modeling (FDM). To overcome the weak bonding strength of each printed layer during FDM, a catalyst-free photo-crosslinkable functional group derived from biocompatible cinnamic acid was embedded into the linear copolyesters as in situ crosslinking points during FDM printing. Under ultraviolet-assisted irradiation, the resulting 4D scaffold models demonstrated excellent SME, desirable mechanical performance, and good stability in a water environment owing to the chemical bonding between each layer. Moreover, the excellent biocompatibility of the scaffold was evaluated in vitro and in vivo. The developed composite scaffolds could be used for minimally invasive soft tissue repair.

Development of Gelatin-Based Shape-Memory Polymer Scaffolds with Fast Responsive Performance and Enhanced Mechanical Properties for Tissue Engineering Applications

Shape-memory polymers (SMPs) can be defined as a reversibly changing form through deformation and recovery by external stimuli. However, there remain application limitations of SMPs, such as complicated preparation processes and slow shape recovery. Here, we designed gelatin-based shape-memory scaffolds by a facile dipping method in tannic acid solution. The shape-memory effect of scaffolds was attributed to the hydrogen bond between gelatin and tannic acid, which acts as the net point. Moreover, gelatin (Gel)/oxidized gellan gum (OGG)/calcium chloride (Ca) was intended to induce faster and more stable shape-memory behavior through the introduction of a Schiff base reaction. The chemical, morphological, physicochemical, and mechanical properties of the fabricated scaffolds were evaluated, and those results showed that the Gel/OGG/Ca had improved mechanical properties and structural stability compared with other scaffold groups. Additionally, Gel/OGG/Ca exhibited excellent shape-recovery behavior of 95.8% at 37 °C. As a consequence, the proposed scaffolds can be fixed to the temporary shape at 25 °C in just 1 s and recovered to the original shape at 37 °C within 30 s, implying a great potential for minimally invasive implantation.

Fabrication of Biodegradable and Biocompatible Functional Polymers for Anti-Infection and Augmenting Wound Repair

The problem of bacteria-induced infections threatens the lives of many patients. Meanwhile, the misuse of antibiotics has led to a significant increase in bacterial resistance. There are two main ways to alleviate the issue: one is to introduce antimicrobial agents to medical devices to get local drug releasing and alleviating systemic toxicity and resistance, and the other is to develop new antimicrobial methods to kill bacteria. New antimicrobial methods include cationic polymers, metal ions, hydrophobic structures to prevent bacterial adhesion, photothermal sterilization, new biocides, etc. Biodegradable biocompatible synthetic polymers have been widely used in the medical field. They are often used in tissue engineering scaffolds as well as wound dressings, where bacterial infections in these medical devices can be serious or even fatal. However, such materials usually do not have inherent antimicrobial properties. They can be used as carriers for drug delivery or compounded with other antimicrobial materials to achieve antimicrobial effects. This review focuses on the antimicrobial behavior, preparation methods, and biocompatibility testing of biodegradable biocompatible synthetic polymers. Degradable biocompatible natural polymers with antimicrobial properties are also briefly described. Finally, the medical applications of these polymeric materials are presented.

Next-Generation 3D Scaffolds for Nano-Based Chemotherapeutics Delivery and Cancer Treatment

Cancer is the leading cause of death after cardiovascular disease. Despite significant advances in cancer research over the past few decades, it is almost impossible to cure end-stage cancer patients and bring them to remission. Adverse effects of chemotherapy are mainly caused by the accumulation of chemotherapeutic agents in normal tissues, and drug resistance hinders the potential therapeutic effects and curing of this disease. New drug formulations need to be developed to overcome these problems and increase the therapeutic index of chemotherapeutics. As a chemotherapeutic delivery platform, three-dimensional (3D) scaffolds are an up-and-coming option because they can respond to biological factors, modify their properties accordingly, and promote site-specific chemotherapeutic deliveries in a sustainable and controlled release manner. This review paper focuses on the features and applications of the variety of 3D scaffold-based nano-delivery systems that could be used to improve local cancer therapy by selectively delivering chemotherapeutics to the target sites in future.

Poly(DL-lactic acid) scaffolds as a bone targeting platform for the co-delivery of antimicrobial agents against S. aureus-C. albicans mixed biofilms

New strategies for the treatment of polymicrobial bone infections are required. In this study, the co-delivery of two antimicrobials by poly(D,L-lactic acid) (PDLLA) scaffolds was investigated in a polymicrobial biofilm model. PDLLA scaffolds were prepared by solvent casting/particulate leaching methodology, incorporating minocycline and voriconazole as clinically relevant antimicrobial agents. The scaffolds presented a sponge-like appearance, suitable to support cell proliferation and drug release. Single- and dual-species biofilm models of Staphylococcus aureus and Candida albicans were developed and characterized. S. aureus presented a higher ability to form single-species biofilms, compared to C. albicans. Minocycline and voriconazole-loaded PDLLA scaffolds showed activity against S. aureus and C. albicans single- and dual-biofilms. Ultimately, the cytocompatibility/functional activity of PDLLA scaffolds observed in human MG-63 osteosarcoma cells unveil their potential as a next-generation co-delivery system for antimicrobial therapy in bone infections.

Biodegradable Microparticles for Regenerative Medicine: A State of the Art and Trends to Clinical Application

Tissue engineering and cell therapy are very attractive in terms of potential applications but remain quite challenging regarding the clinical aspects. Amongst the different strategies proposed to facilitate their implementation in clinical practices, biodegradable microparticles have shown promising outcomes with several advantages and potentialities. This critical review aims to establish a survey of the most relevant materials and processing techniques to prepare these micro vehicles. Special attention will be paid to their main potential applications, considering the regulatory constraints and the relative easiness to implement their production at an industrial level to better evaluate their application in clinical practices.

In vitro drug release and antibacterial activity evaluation of silk fibroin coated vancomycin hydrochloride loaded poly (lactic-co-glycolic acid) (PLGA) sustained release microspheres

Currently, the treatment of osteomyelitis poses a great challenge to clinical orthopedics. The use of biodegradable materials combined with antibiotics provides a completely new option for the treatment of osteomyelitis. In this study, vancomycin hydrochloride (VANCO) loaded poly (lactic-co-glycolic acid) (PLGA) microspheres were prepared by a double emulsion solvent evaporation method, and the in vitro drug release behaviors of the drug loaded microspheres were explored after coating with different concentrations of silk fibroin (SF). Drug loading, encapsulation efficiency, Scanning electron microscopy, particle size analysis, Fourier transform infrared spectroscopy, hydrophilicity, in vitro drug release, and in vitro antibacterial activity were evaluated. The results showed that the drug loading of vancomycin loaded PLGA microspheres was (24.11 ±1.72)%, and the encapsulation efficiency was (48.21 ±3.44)%. The in vitro drug release indicated that the drug loaded microspheres showed an obvious initial burst release, and the drug loaded microspheres coated with SF could alleviate the initial burst release in varying degrees. It also can reduce the amount of cumulative drug release, and the effect of microspheres coated with 0.1% concentration of SF is the best. The time of in vitro drug release in different groups of drug loaded microspheres can be up to 28 days. The microspheres coated with (0.1%SF) or without (0%SF) SF showed a cumulative release of (82.50±3.51)% and (67.70±3.81)%,respectively. Therefore, the surface coating with SF of vancomycin loaded microspheres can alleviate the initial burst release, reduce the cumulative drug release, potentially prolong the drug action time, and improve the anti-infection effect.

Nanoparticle-containing electrospun nanofibrous scaffolds for sustained release of SDF-1α

Chemokines such as stromal cell-derived factor-1α (SDF-1α) regulate the migration of cancer cells that can spread from their primary tumor site by migrating up an SDF-1α concentration gradient, facilitating their local invasion and metastasis. Therefore, the implantation of SDF-1α-releasing scaffolds can be a useful strategy to trap cancer cells expressing the CXCR4 receptor. In this work, SDF-1α was encapsulated into poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles and subsequently electrospun with chitosan to produce nanofibrous scaffolds of average fiber diameter of 261 ± 45 nm, intended for trapping glioblastoma (GBM) cells. The encapsulated SDF-1α maintained its biological activity after the electrospinning process as assessed by its capacity to induce the migration of cancer cells. The scaffolds could also provide sustained release of SDF-1α for at least 5 weeks. Using NIH3T3 mouse fibroblasts, human Thp-1 macrophages, and rat primary astrocytes we showed that the scaffolds possessed high cytocompatibility in vitro. Furthermore, a 7-day follow-up of Fischer rats bearing implanted scaffolds demonstrated the absence of adverse effects in vivo. In addition, the nanofibrous structure of the scaffolds provided excellent anchoring sites to support the adhesion of human GBM cells by extension of their pseudopodia. The scaffolds also demonstrated slow degradation kinetics, which may be useful in maximizing the time window for trapping GBM cells. As surgical resection does not permit a complete removal of GBM tumors, our results support the future implantation of these scaffolds into the walls of the resection cavity to evaluate their capacity to attract and trap the residual GBM cells in the brain.

Shape memory materials and 4D printing in pharmaceutics

Shape memory materials (SMMs), including alloys and polymers, can be programmed into a temporary configuration and then recover the original shape in which they were processed in response to a triggering external stimulus (e.g. change in temperature or pH, contact with water). For this behavior, SMMs are currently raising a lot of attention in the pharmaceutical field where they could bring about important innovations in the current treatments. 4D printing involves processing of SMMs by 3D printing, thus adding shape evolution over time to the already numerous customization possibilities of this new manufacturing technology. SMM-based drug delivery systems (DDSs) proposed in the scientific literature were here reviewed and classified according to the target pursued through the shape recovery process. Administration route, therapeutic goal, temporary and original shape, triggering stimulus, main innovation features and possible room for improvement of the DDSs were especially highlighted.

Electrospun Shape Memory Polymer Micro-/Nanofibers and Tailoring Their Roles for Biomedical Applications

Shape memory polymers (SMPs) as a relatively new class of smart materials have gained increasing attention in academic research and industrial developments (e.g., biomedical engineering, aerospace, robotics, automotive industries, and smart textiles). SMPs can switch their shape, stiffness, size, and structure upon being exposed to external stimuli. Electrospinning technique can endow SMPs with micro-/nanocharacteristics for enhanced performance in biomedical applications. Dynamically changing micro-/nanofibrous structures have been widely investigated to emulate the dynamical features of the ECM and regulate cell behaviors. Structures such as core-shell fibers, developed by coaxial electrospinning, have also gained potential applications as drug carriers and artificial blood vessels. The clinical applications of micro-/nanostructured SMP fibers include tissue regeneration, regulating cell behavior, cell growth templates, and wound healing. This review presents the molecular architecture of SMPs, the recent developments in electrospinning techniques for the fabrication of SMP micro-/nanofibers, the biomedical applications of SMPs as well as future perspectives for providing dynamic biomaterials structures.

Biological analysis of an innovative biodegradable antibiotic eluting bioactive glass/gypsum composite bone cement for treating experimental chronic MRSA osteomyelitis

A multi-barrier antibiotics loaded biodegradable composite bone cement for resolving chronic osteomyelitis has been studied to understand the physico-mechanical properties, drug loading/eluting efficiency, and different merits and demerits prior to clinical application. After successful induction of bone infection in 28 rabbits using methicillin-resistant Staphylococcus aureus (MRSA) strains, calcium sulfate/bioactive glass based composite cement was implanted in 12 defects to assess its performance over parenteral therapy with microscopic and radiological examination for 90 days. The composite cement revealed acceptable physico-mechanical properties and controlled drug elution kinetics. Furthermore, the antibiotics concentrations in bone up to 42 days were sufficient to kill MRSA without eliciting adverse drug reactions. The striking feature of platelets aggregation by composite cement could assist bone healing. The controlled degradation with simultaneous entrapment of composite cement within the osteoid tissues and complete repair of infected cortical defects (holes) in rabbit tibia at 6 weeks indicated the excellent anti-infective and osteoconductive properties of composite cement. Thus, the animal study demonstrated the superiority of composite over injectable antibiotic therapy based on infection resolution and bone regeneration. We thereby conclude that the composite cement can be effectively applied in the treatment of resistant cases of chronic osteomyelitis.

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Described the preparation method of multi-barrier CS/BG composite bone cement.

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Made by coating the antibiotics loaded porous BG granules with PLGA and α-CSH.

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Introduced antibiotics elution study in ideal immersion medium.

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Beneficial role of PLGA on drug release and activation of platelets by cement was explored.

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New cement showed great potential to repair bone infection and to hasten osteosynthesis.

Chitosan-coated hydroxyapatite and drug-loaded polytrimethylene carbonate/polylactic acid scaffold for enhancing bone regeneration

Biocompatible polymers and drug-delivery scaffolds have driven development in bone regeneration. In this study, we fabricated a chitosan (CS)-coated polytrimethylene carbonate (PTMC)/polylactic acid (PLLA)/oleic acid-modified hydroxyapatite (OA-HA)/vancomycin hydrochloride (VH) microsphere scaffold for drug release with excellent biocompatibility. The incorporation of PLLA, OA-HA, and VH into PTMC microspheres not only slowed the biodegradability of the scaffold but also enhanced its mechanical properties and surface properties. Moreover, the CS coating stimulated extensive adhesion of osteoblasts before OA-HA incorporation, which facilitated the controlled release of OA-HA. The scaffolds were characterized via scanning electron microscopy, in vitro comprehensive performance testing, cell culturing, and microcomputer tomography scanning. The results indicated that the surface of the composite microsphere scaffold was suitable for osteoblast adhesion. Additionally, the release of OA-HA stimulated osteogenic proliferation. Our findings suggest that the CS-PTMC/PLLA/OA-HA/VH microsphere scaffold is promising for bone tissue engineering applications.

Advanced reconfigurable scaffolds fabricated by 4D printing for treating critical-size bone defects of irregular shapes

While scaffold-based tissue engineering has been widely used to treat bone critical-size defects, challenges such as implantation of scaffolds in defects with irregular shapes and implantation of scaffolds through minimally invasive surgery remain in the tissue engineering field. Customized bioactive bone tissue engineering scaffolds with reconfigurable capability for both easy scaffold implantation and perfect shape fitting in irregularly shaped bone defects are therefore needed. Herein, applying 4D printing, photothermal-responsive shape memory bone tissue engineering scaffolds are constructed by incorporating black phosphorus nanosheets and osteogenic peptide into β-tricalcium phosphate/poly(lactic acid-co-trimethylene carbonate) (TCP/P(DLLA-TMC)) nanocomposite scaffolds. When near-infrared irradiation is applied to customized scaffolds on-demand, scaffold temperature rapidly increases to 45 °C, enabling scaffold shape reconfiguration for easy scaffold implantation and precise fitting in irregular bone defects. Once the implantation is finished, scaffold temperature rapidly decreases to 37 °C and scaffolds display mechanical properties comparable to those of human cancellous bone. The improved osteogenesis in bone defect sites is then initiated through pulsed peptide release from scaffolds. Compact integration of reconfigurable scaffolds in rat cranial bone defects and improved new bone formation are demonstrated through micro-computed tomography and histochemical analyses. This study shows a facile method to clinically treat bone defects of irregular shapes.

Injectable Multicomponent Biomimetic Gel Composed of Inter-Crosslinked Dendrimeric and Mesoporous Silica Nanoparticles Exhibits Highly Tunable Elasticity and Dual Drug Release Capacity

There is a growing need for cartilage defect grafts that are structurally adaptable to possess multifaceted functions to promote bone regeneration, sustain medication efficacy, and preferably remain injectable but solidify quickly upon injection. In this work, we developed an injectable multicomponent biomimetic gel (MBG) by integrating polyamidoamine dendrimer G3 (G3), mesoporous silica nanoparticles (MSNs), and dendrimer-templated silver nanoparticles (G3-Ag) into a well-defined cross-linked network. MBGs composed of one particulate component (G3 alone), i.e., MBG-1, two particulate components (G3 and MSN-NH2), i.e., MBG-2, and three particulate components (G3, MSN-NH2, and G3-Ag), i.e., MBG-3, were prepared by inter-cross-linking dendrimeric and mesoporous silica nanoparticles with poly(ethylene glycol) diglycidyl ether (PEG-DGE, Mn = 2000 g/mol) via the facile amine-epoxy click reaction. The water-soluble antibiotic isoniazid was loaded to the cross-linked PEG network, whereas the hydrophobic antibiotic rifampicin was encapsulated into mesoporous MSNs. Our studies revealed that elasticity and mechanical strengths could be modulated and enhanced significantly with the inclusion of MSNs and silver nanoparticles. Isoniazid was released rapidly while rifampicin was released over an extended period of time. In addition, MBGs showed injectability, high swelling capacity, structural stability, and cytocompatibility. Taken together, MBGs have shown structural features that allow for the development of injectable gel grafts with the ability to promote cartilage defect repair and offer antibiotic medication benefits.

Vancomycin hydrochloride-loaded stearic acid/lauric acid in situ forming matrix for antimicrobial inhibition in patients with joint infection after total knee arthroplasty

Knee joint infection following total knee arthroplasty (TKA) is a serious condition and the treatments are complicated. The intra-articular solvent exchange-induced in situ forming matrix is of interest for modulating the release of antibiotics with a high drug concentration and a long period of exposed time at the target site. Stearic acid (S) and lauric acid (L) at various ratios were used as matrix formers by dissolving them in biocompatible solvents such as N-methyl pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Their matrix formation behaviors in phosphate buffer (pH7.4) and hyaluronic acid (HA) solution were evaluated. Also, the density, viscosity, injectability, solvent diffusion, in vitro degradability and drug release using the dialysis tube method were investigated. The L:S ratio of 1:1 in DMSO exhibited rapid matrix formation and a remarkably low viscosity (7.67±0.03 cp) with acceptable injectability (0.608±0.027N and 0.867±0.010N through 18-G and 27-G, respectively). Vancomycin HCl (V)-loaded L/S in situ forming matrix still provided ease of injection (1.079±0.215N and 1.230±0.145N through 18-G and 27-G needle, respectively) with fatty acid matrix formation after solvent exchange within 1min, whilst V sustainably released over 6days. It also presented effective antimicrobial activities against standard Staphylococcus aureus and methicillin-resistant Staphylococcus aureus strains. Therefore, V-loaded solvent exchange-induced in situ forming matrix using L and S as the matrix formers may be a potential local delivery system for treating knee joint infections occurring after TKA in the future.

One Year Evaluation of Material Properties Changes of Polylactide Parts in Various Hydrolytic Degradation Conditions

Biodegradable biocompatible materials are widely used in medical applications. Determining the possibility of using biodegradable materials depends on determining the changes in their parameters over time due to degradation. The current scientific research on biodegradable materials has presented results based on research methods characterized by the different geometry and cross-section size of the specimen, type of degradation medium, or different pH value of the medium or maximum degradation time. This paper presents the results of a one-year study on the influence of the type of degradation medium on the changes in mechanical behavior and the uptake of the degradation medium by biodegradable specimens with large cross-sections. In addition, a prototype of a test stand was created, which allowed for the specimens to be stored vertically to ensure regular medium exposure and eliminate the interaction of the surface of the tested specimens with the sides of the container. The obtained results allowed the statistical significance of differences in the mechanical parameters determined in the uniaxial tensile test after 2, 4, 6, 12, 26, 39, and 52 weeks of degradation to be indicated depending on the type of degradation medium. It was proven that the changes in mechanical behavior depend on the percentage change in the mass of the specimens during degradation. The percentage change in mass depends on the type of degradation medium. Based on the results of this research, it was noted that in long-term degradation above 12 weeks, buffered sodium chloride solution is the optimal choice for the degradation medium. However, distilled water or physiological saline solution can be used as an alternative during the degradation period for up to 12 weeks.

Fabrication Strategies of Scaffolds for Delivering Active Ingredients for Tissue Engineering

Designing scaffolds with optimum properties is an essential factor for tissue engineering success. They can be seeded with isolated cells or loaded with drugs to stimulate the body ability to repair or regenerate the injured tissues by acting as centers for new tissue formation. Recently, scaffolds gained a significant interest as principal candidates for tissue engineering due to overcoming the autograft or allograft's associated problems. The advancement of the tissue engineering field relies mainly on the introduction of new biomaterials for scaffolds' fabrication. This review presents and criticizes different scaffolds' fabrication techniques with particular emphasis on the fibrous, injectable in situ forming, foam, 3D freeze-dried, 3D printed, and 4D scaffolds. This article highlights on scaffolds' composition which would be beneficial for developing scaffolds that could potentially help to meet the demand for both drug delivery and tissue regeneration.

3D printed poly(ε-caprolactone) scaffolds function with simvastatin-loaded poly(lactic-co-glycolic acid) microspheres to repair load-bearing segmental bone defects

Repairing critical-sized bone defects has been a major challenge for orthopedic surgeons in the clinic. The generation of functioning bone tissue scaffolds using osteogenic induction factors is a promising method to facilitate bone healing. In the present study, three-dimensional (3D) printing of a poly(lactic-co-glycolic acid) (PLGA) scaffold with simvastatin (SIM) release functioning was generated by rapid prototyping, which was incorporated with collagen for surface activation, and was finally mixed with SIM-loaded PLGA microspheres. In vitro assays with bone marrow-derived mesenchymal stem cells were conducted. For the in vivo study, scaffolds were implanted into segmental defects created on the femurs of Sprague-Dawley rats. At 4 and 12 weeks following surgery, X-ray, micro-computed tomography and histological analysis were performed in order to evaluate bone regeneration. The results demonstrated that collagen functionalization of PLGA produced better cell adhesion, while the sustained release of SIM promoted greater cell proliferation with no significant cytotoxicity, compared with the blank PCL scaffold. Furthermore, in vivo experiments also confirmed that SIM-loaded scaffolds played a significant role in promoting bone regeneration. In conclusion, the present study successfully manufactured a 3D printing PLGA scaffold with sustained SIM release, which may meet the requirements for bone healing, including good mechanical strength and efficient osteoinduction ability. Thus, the results are indicative of a promising bone substitute to be used in the clinic.

Antimicrobial Activity of 3D-Printed Poly(ε-Caprolactone) (PCL) Composite Scaffolds Presenting Vancomycin-Loaded Polylactic Acid-Glycolic Acid (PLGA) Microspheres

BACKGROUND The aim of this study was to design and test a novel composite scaffold with antibacterial efficacy for treating bone infections using a three-dimensional (3D) printed poly(ε-caprolactone) (PCL) scaffold coated with polydopamine (PDA) for the adsorption of polylactic acid-glycolic acid (PLGA) microspheres loaded with vancomycin. MATERIAL AND METHODS Vancomycin-loaded PLGA microspheres were produced by the double-emulsion method, and microsphere morphology, drug-loading dosage, encapsulation efficiency, average diameter, and release characteristics were examined. Composite scaffolds were prepared by adsorption of the microspheres on PDA-coated, 3D-printed PCL scaffolds, and scaffold morphology, biocompatibility, vancomycin release, and antibacterial efficacy were evaluated. RESULTS The vancomycin-loaded microspheres were smooth, round, uniform in size, and had no adhesion phenomenon, and exhibited sustained release of vancomycin from the microspheres for more than 4 weeks. Upon modification with PDA, the PCL scaffold changed from white to black, and after microsphere adsorption, dot-like white particles were seen. On scanning electron microscopy, PDA particles were observed on the PCL/PDA composite scaffolds, and PLGA microspheres were evenly dispersed over the PDA coating on the PCL/PDA/PLGA composite scaffolds. Cell viability assays showed that the adhesion and proliferation of rabbit bone mesenchymal stem cells were greater on the PCL/PDA scaffolds than on unmodified PCL scaffolds. Microsphere adsorption had no significant effect on cell proliferation. In vitro release of vancomycin from the composite scaffolds was observed for more than 4 weeks, and observation of the inhibition zone on agar plates of Staphylococcus aureus showed that the scaffolds maintained their antibacterial effect for more than 4 weeks. CONCLUSIONS The 3D-printed, PDA-coated PCL scaffold carrying vancomycin-loaded PLGA microspheres exhibited good biocompatibility and a sustained antibacterial effect in vitro.

A Review on Properties of Natural and Synthetic Based Electrospun Fibrous Materials for Bone Tissue Engineering

Bone tissue engineering is an interdisciplinary field where the principles of engineering are applied on bone-related biochemical reactions. Scaffolds, cells, growth factors, and their interrelation in microenvironment are the major concerns in bone tissue engineering. Among many alternatives, electrospinning is a promising and versatile technique that is used to fabricate polymer fibrous scaffolds for bone tissue engineering applications. Copolymerization and polymer blending is a promising strategic way in purpose of getting synergistic and additive effect achieved from either polymer. In this review, we summarize the basic chemistry of bone, principle of electrospinning, and polymers that are used in bone tissue engineering. Particular attention will be given on biomechanical properties and biological activities of these electrospun fibers. This review will cover the fundamental basis of cell adhesion, differentiation, and proliferation of the electrospun fibers in bone tissue scaffolds. In the last section, we offer the current development and future perspectives on the use of electrospun mats in bone tissue engineering.

Dual drug loaded coaxial electrospun PLGA/PVP fiber for guided tissue regeneration under control of infection

Electrospinning promisingly fabricate mats for Guided Tissue Regeneration (GTR). Due to a chronic inflammatory pathology in periodontal, it is highly desirable to develop a novel GTR mats to realize tissue regeneration under control of infection. In the study, coaxial electrospinning was firstly conducted to fabricate dual drug loaded fiber mats with core/shell structure. Naringin-loaded polyvinylpyrrolidone was designed as core fiber to enrich tissue regeneration and metronidazole-loaded poly(lactic-co-glycolic acid) as shell fiber to inhibit bacterial. TEM revealed that the fibers with distinct core/shell structure were in an outer diameter of 1.5-1.7 μm with an inner diameter of <1.0 μm. The loading of dual drug decreased the tensile strength and elongation of the coaxial fiber mats. On in vitro assessment, metronidazole had a short-term release while naringin had a long-term release behavior in all the coaxial mats. The colonization of anaerobic bacteria on the mats effectively were inhibited over 21 days. Furthermore, the dual drug loaded coaxial fiber mats were observed to positively supported the adhesion and proliferation of MC3T3-E1 and was conductive to high alkaline phosphatase express. Thus, a simple and effective coaxial electrospinning approach was demonstrated for the fabrication of anti-infective GTR mats with promoting tissue regeneration.

Time-of-flight secondary ion mass spectrometry analyses of vancomycin

As an antibiotic that prevents and treats infections caused by Gram-positive bacteria such as Staphylococcus aureus, vancomycin incorporated in a biodegradable polymer poly(lactide-co-glycolide) provides opportunities to construct controlled-release drug delivery systems. Developments associated with this promising system have been largely concentrated on areas of drug delivery kinetics and biodegradability. In order to provide surface analytical approaches to this important system, the authors demonstrate applicability of time-of-flight secondary ion mass spectrometry (TOF-SIMS) in three-dimensional molecular imaging for a model system consisting of alternating layers of ploy(lactide-co-glycolide) and vancomycin. TOF-SIMS imaging clarified that the two chemicals can undergo phase separation when dimethyl sulfoxide is used as the solvent. The authors identified two diagnostic ions that are abundant and structural moieties of vancomycin. The results on TOF-SIMS imaging and depth profiling vancomycin provide useful information for further applications of TOF-SIMS in the development of antibiotic drug delivery systems involving the use of vancomycin.