Enhanced osteogenesis using poly (l-lactide-co-d, l-lactide)/poly (acrylic acid) nanofibrous scaffolds in presence of dexamethasone-loaded molecularly imprinted polymer nanoparticles

Potential use of a bone tissue engineering scaffold based on electrospun poly (ɛ-caprolactone) - Poly (vinyl alcohol) hybrid nanofibers containing modified cockle shell nanopowder

Today, the construction of scaffolds promoting the differentiation of stem cells is an intelligent innovation that accelerates the differentiation toward the target tissue. The use of calcium and phosphate compounds is capable of elevating the precision and efficiency of the osteogenic differentiation of stem cells. In this research, osteoconductive electrospun poly (ɛ-caprolactone) (PCL) - poly (vinyl alcohol) (PVA) hybrid nanofibrous scaffolds containing modified cockle shell (CS) nanopowder were prepared and investigated. In this regard, the modified CS nanopowder was prepared by grinding and modifying with phosphoric acid, and it was then added to PVA nanofibers at different weight percentages. Based on the SEM images, the optimum content of the modified CS nanopowder was set at 7 wt %, since reaching the threshold of agglomeration restricted this incorporation. In the second step, the PVA-CS7 nanofibrous sample was hybridized with different PCL ratios. Concerning the hydrophilicity and mechanical strength, the sample named PCL50-PVA50-CS7 was ultimately selected as the optimized and suitable candidate scaffold for bone tissue application. The accelerated hydrolytic degradation of the sample was also studied by FTIR and SEM analyses, and the results confirmed that the mineral deposits of CS are available approximately 7 days for mesenchymal stem cells. Moreover, Alizarin red staining illustrated that the presence of CS in the PCL50-PVA50-CS7 hybrid nanofibrous scaffold may potentially lead to an increase in calcium deposits with high precipitates, authenticating the differentiation of stem cells towards osteogenic cells.

Fabrication and characterization of a multi-functional GBR membrane of gelatin-chitosan for osteogenesis and angiogenesis

Guided bone regeneration (GBR) membranes are widely used to treat bone defects. In this study, sequential electrospinning and electrospraying techniques were used to prepare a dual-layer GBR membrane composed of gelatin (Gel) and chitosan (CS) containing simvastatin (Sim)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres (Sim@PLGA/Gel-CS). As a GBR membrane, Sim@PLGA/Gel-CS could act as a barrier to prevent soft tissue from occupying regions of bone tissue. Furthermore, compared with traditional GBR membranes, Sim@PLGA/Gel-CS played an active role on stimulating osteogenesis and angiogenesis. Determination of the physical, chemical, and biological properties of Sim@PLGA/Gel-CS membranes revealed uniform sizes of the nanofibers and microspheres and appropriate morphologies. Fourier-transform infrared spectroscopy was used to characterize the interactions between Sim@PLGA/Gel-CS molecules and the increase in the number of amide groups in crosslinked membranes. The thermal stability and tensile strength of the membranes increased after N-(3-dimethylaminopropyl)-N9- ethylcarbodiimide/N-hydroxysuccinimide crosslinking. The increased fiber density of the barrier layer decreased fibroblast migration compared with that in the osteogenic layer. Osteogenic function was indicated by the increased alkaline phosphatase activity, calcium deposition, and neovascularization. In conclusion, the multifunctional effects of Sim@PLGA/Gel-CS on the barrier and bone microenvironment were achieved via its dual-layer structure and simvastatin coating. Sim@PLGA/Gel-CS has potential applications in bone tissue regeneration.

Dexamethasone and doxycycline functionalized nanoparticles enhance osteogenic properties of titanium surfaces

OBJECTIVES

To evaluate the effect of doxycycline and dexamethasone doped nanoparticles covering titanium surfaces, on osteoblasts proliferation and differentiation.

METHODS

Doxycycline and dexamethasone doped polymeric nanoparticles were applied on titanium discs (Ti-DoxNPs and Ti-DexNPs). Undoped NPs and uncovered Ti discs were used as control. Human MG-63 osteoblast-like cells were cultured. Osteoblasts proliferation was tested by MTT assay. Alkaline phosphatase activity was analyzed. Differentiation gene expression was assessed by real-time quantitative polymerase chain reaction. Scanning Electron Microscopy was performed to assess osteoblasts morphology. Mean comparisons were conducted by ANOVA and Wilcoxon or Tukey tests (p < 0.05).

RESULTS

No differences in osteoblasts proliferation were found. Osteoblasts grown on Ti-DoxNPs significantly increased alkaline phosphatase activity. Doxycycline and dexamethasone nanoparticles produced an over-expression of the main osteogenic proliferative genes (TGF-β1, TGF-βR1 and TGF-βR2). The expression of Runx-2 was up-regulated. The osteogenic proteins (AP, OSX and OPG) were also overexpressed on osteoblasts cultured on Ti-DoxNPs and Ti-DexNPs. The OPG/RANKL ratio was the highest when DoxNPs were present (75-fold increase with respect to the control group). DexNPs also produced a significantly higher OPG/RANKL ratio with respect to the control (20 times higher). Osteoblasts grown on titanium discs were mainly flat and polygonal in shape, with inter-cellular connections. In contrast, osteoblasts cultured on Ti-DoxNPs or Ti-DexNPs were found to be spindle-shaped and had abundant secretions on their surfaces.

SIGNIFICANCE

DoxNPs and DexNPs were able to stimulate osteoblasts differentiation when applied on titanium surfaces, being considered potential inducers of osteogenic environment when performing regenerative procedures around titanium dental implants.

Printable hyaluronic acid hydrogel functionalized with yeast-derived peptide for skin wound healing

Targeted delivery of bioactive agents, growth factors, and drugs to skin wounds is a growing trend in biomaterials development for wound healing. This study presents a printable hyaluronic acid (HA) based hydrogel to deliver yeast-derived ACE-inhibitory peptide of VLSTSFPPW (VW-9) to the wound site. We first conjugated tyramine (Ty) on the carboxyl groups of the HA to form a phenol-functionalized HA (HA-Ty); then, the carboxylic acid groups of HA-Ty were aminated with ethylenediamine (HA-Ty-NH2). The primary amine groups of the HA-Ty-NH2 could then react with the carboxylic acids of the peptide. The hydrogel was then 3D printed and crosslinked with visible light. The modification of HA was confirmed by 1H NMR and FTIR. The swelling capacity of the conjugated hydrogels was 1.5-fold higher compared to the HA-Ty-NH2 hydrogel. The conjugated peptide did not affect on rheological properties and morphology of the hydrogels. The 3T3-L1 fibroblast cells seeded on the peptide-modified hydrogels exhibited higher viability than the hydrogels without the peptide, indicating that the peptide-enriched hydrogels may have the potential for wound healing applications.

Molecularly Imprinted Nanomaterials with Stimuli Responsiveness for Applications in Biomedicine

The review aims to summarize recent reports of stimuli-responsive nanomaterials based on molecularly imprinted polymers (MIPs) and discuss their applications in biomedicine. In the past few decades, MIPs have been proven to show widespread applications as new molecular recognition materials. The development of stimuli-responsive nanomaterials has successfully endowed MIPs with not only affinity properties comparable to those of natural antibodies but also the ability to respond to external stimuli (stimuli-responsive MIPs). In this review, we will discuss the synthesis of MIPs, the classification of stimuli-responsive MIP nanomaterials (MIP-NMs), their dynamic mechanisms, and their applications in biomedicine, including bioanalysis and diagnosis, biological imaging, drug delivery, disease intervention, and others. This review mainly focuses on studies of smart MIP-NMs with biomedical perspectives after 2015. We believe that this review will be helpful for the further exploration of stimuli-responsive MIP-NMs and contribute to expanding their practical applications especially in biomedicine in the near future.

Hybrid Systems of Nanofibers and Polymeric Nanoparticles for Biological Application and Delivery Systems

Nanomedicine is a new discipline resulting from the combination of nanotechnology and biomedicine. Nanomedicine has contributed to the development of new and improved treatments, diagnoses, and therapies. In this field, nanoparticles have notable importance due to their unique properties and characteristics, which are useful in different applications, including tissue engineering, biomarkers, and drug delivery systems. Electrospinning is a versatile technique used to produce fibrous mats. The high surface area of the electrospun mats makes them suitable for applications in fields using nanoparticles. Electrospun mats are used for tissue engineering, wound dressing, water-treatment filters, biosensors, nanocomposites, medical implants, protective clothing materials, cosmetics, and drug delivery systems. The combination of nanoparticles with nanofibers creates hybrid systems that acquire properties that differ from their components' characteristics. By utilizing nanoparticles and nanofibers composed of dissimilar polymers, the two synergize to improve the overall performance of electrospinning mats and nanoparticles. This review summarizes the hybrid systems of polymeric nanoparticles and polymeric nanofibers, critically analyzing how the combination improves the properties of the materials and contributes to the reduction of some disadvantages found in nanometric devices and systems.

Kiwi extract-incorporated poly(ɛ-caprolactone)/cellulose acetate blend nanofibers for healing acceleration of burn wounds

Kiwi extract (KE) including different components such as quercetin, vitamins C and E, and actinides has been known as a debridement agent for burn wounds. In this study, electrospun poly(ɛ-caprolactone)/cellulose acetate blend nanofibers incorporating KE (PCL/CA/KE) were prepared and their performance was evaluated for healing acceleration of burn wounds. The physicochemical characterization of PCL/CA/KE nanofibers showed an average diameter of ∼420 nm, porosity of 70%, water contact angle of 61°, and water uptake of ∼220%. Moreover, the continuous release trend of KE from PCL/CA blend nanofibers happened during 24 h and the release mechanism was governed by the Fickian diffusion. Besides the cytocompatibility of PCL/CA/KE nanofibers, their in vivo experiments revealed that the bioactive wound dressing based on the sample has higher wound closure compared to KE after 21 days. Histopathology of wounds dressed by PCL/CA/KE nanofibers indicated epidermal formation along with a fully extended layer. Eventually, the obtained results confirmed that the PCL/CA/KE nanofibrous sample was a promising wound dressing for burn wound healing.

Bio-Inspired Imprinting Materials for Biomedical Applications

Inspired by the recognition mechanism of biological molecules, molecular imprinting techniques (MITs) are imparted with numerous merits like excellent stability, recognition specificity, adsorption properties, and easy synthesis processes, and thus broaden the avenues for convenient fabrication protocol of bio-inspired molecularly imprinted polymers (MIPs) with desirable functions to satisfy the extensive demands of biomedical applications. Herein, the recent research progress made with respect to bio-inspired imprinting materials is discussed in this review. First, the underlying mechanism and basic components of a typical molecular imprinting procedure are briefly explored. Then, emphasis is put on the introduction of diverse MITs and novel bio-inspired imprinting materials. Following these two sections, practical applications of MIPs in the field of biomedical science are focused on. Last but not least, perspectives on the remaining challenges and future development of bio-inspired imprinting materials are presented.

Chitosan-Gelatin Films Cross-Linked with Dialdehyde Cellulose Nanocrystals as Potential Materials for Wound Dressings

In this study, thin chitosan-gelatin biofilms cross-linked with dialdehyde cellulose nanocrystals for dressing materials were received. Two types of dialdehyde cellulose nanocrystals from fiber (DNCL) and microcrystalline cellulose (DAMC) were obtained by periodate oxidation. An ATR-FTIR analysis confirmed the selective oxidation of cellulose nanocrystals with the creation of a carbonyl group at 1724 cm-1. A higher degree of cross-linking was obtained in chitosan-gelatin biofilms with DNCL than with DAMC. An increasing amount of added cross-linkers resulted in a decrease in the apparent density value. The chitosan-gelatin biofilms cross-linked with DNCL exhibited a higher value of roughness parameters and antioxidant activity compared with materials cross-linked with DAMC. The cross-linking process improved the oxygen permeability and anti-inflammatory properties of both measurement series. Two samples cross-linked with DNCL achieved an ideal water vapor transition rate for wound dressings, CS-Gel with 10% and 15% addition of DNCL-8.60 and 9.60 mg/cm2/h, respectively. The swelling ability and interaction with human serum albumin (HSA) were improved for biofilms cross-linked with DAMC and DNCL. Significantly, the films cross-linked with DAMC were characterized by lower toxicity. These results confirmed that chitosan-gelatin biofilms cross-linked with DNCL and DAMC had improved properties for possible use in wound dressings.

Preparation of poly(acrylic acid)/tricalcium phosphate nanoparticles scaffold: Characterization and releasing UC-MSCs derived exosomes for bone differentiation

Introduction

This study focused on preparing a multiscale three-dimensional (3D) scaffold using tricalcium phosphate nanoparticles (triCaPNPs) in a substrate of poly(acrylic acid) (PAA) polymer for controlled release of exosomes in bone tissue engineering.

Methods

A scaffold was fabricated with a material mixture containing acrylic acid (AA) monomer, N,N'-methylenebisacrylamide (MBAA), ammonium persulfate (APS), sodium bicarbonate (SBC), and triCaPNPs called composite scaffold (PAA/triCaPNPs) via cross-linking and freeze-drying methods. The synthesis process was easy and without complex multi-steps. Through mimicking the hybrid (organic-inorganic) structure of the bone matrix, we here chose triCaPNPs for incorporation into the PAA polymer. After assessing the physicochemical properties of the scaffold, the interaction of the scaffold with human umbilical cord mesenchymal stem cells (UC-MSCs) such as attachment, proliferation, and differentiation to osteoblast cells was evaluated. In addition, we used DiI-labeled exosomes to verify the exosome entrapment and release from the scaffold.

Results

The polymerization reaction of 3D scaffold was successful. Based on results of physicochemical properties, the presence of nanoparticles in the composite scaffold enhanced the mechanical stiffness, boosted the porosity with a larger pore size range, and offered better hydrophilicity, all of which would contribute to greater cell penetration, proliferation, and then better bone differentiation. In addition, our results indicated that our scaffold could take up and release exosomes, where the exosomes released from it could significantly enhance the osteogenic commitment of UC-MSCs.

Conclusion

The current research is the first study fabricating a multiscale scaffold using triCaPNPs in the substrate of PPA polymer using a cross-linker and freeze-drying process. This scaffold could mimic the nanoscale structure and chemical combination of native bone minerals. In addition, our results suggest that the PAA/triCaPNPs scaffold could be beneficial to achieve controlled exosome release for exosome-based therapy in bone tissue engineering.

Preparation of colloidal nanoparticles PVA-PHEMA from hydrolysis of copolymers of PVAc-PHEMA as anticancer drug carriers

The novel pH-responsive polymer nanoparticles have been widely used for drug delivery and cancer therapy. The pH-sensitive nanoparticles include chemical structures that can accept or donate protons in response to an environmental pH change. Polybases which mostly contain alkaline groups such as amines and hydroxy, accept protons at low pH and are neutral at higher pH values. This study aimed to prepare pH-sensitive colloidal amphiphilic poly(vinyl alcohol-2-hydroxyethyl methacrylate) (PVA-PHEMA) copolymers in cancer therapy applications. For this purpose, poly(vinyl acetate-2-hydroxyethyl methacrylate) (PVAc-PHEMA) copolymer nanoparticles were synthesized in different polymerization medium fractions from water and methanol and different monomer feed concentration. Then acetate groups were hydrolyzed, and the PHEMA-PVA nanoparticles were synthesized. The nanoparticles were further characterized using dynamic light scattering, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis to identify the structural and morphological changes. The Methotrexate (MTX) was loaded into the nanoparticles, and drug release kinetics were evaluated. The results confirmed that PHEMA-PVA copolymeric nanoparticles could be favorably used in cancer therapy.

Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

Novel Molecular Organic Framework Composite Molecularly Imprinted Nanofibrous Membranes with a Bioinspired Viscid Bead Structure for Selective Recognition and Separation of Atrazine

In this work, novel atrazine (ATZ) molecularly imprinted nanofibrous membranes (A-MNMs) with a molecular organic framework (MOF)-based viscid bead structure were developed based on a natural spider-web-inspired strategy for selective separation of ATZ. Poly(vinylidene fluoride)/poly(vinyl alcohol) (PVDF/PVA) blended nanofibrous membranes as the basal membrane were synthesized by electrospinning technology combined with a chemical cross-linking procedure. The most critical design is that MOF nanocrystals as the matrix of the viscid bead structure were assembled on the PVDF/PVA blended nanofibrous membrane surface and the specific recognition sites were efficiently constructed on the surface and pores of the MOF-based viscid bead structure by a surface imprinting strategy. Significantly, the as-synthesized MOF-based viscid bead structure has an enhanced specific surface area, which helps to form abundant specific recognition sites in A-MNMs. Therefore, the A-MNMs with a spider-web-like structure presented an enhanced rebinding capacity (37.62 mg g^-1) and permselectivity (permselectivity factors β were 4.21 and 4.31) toward ATZ. Moreover, the A-MNMs display strong practicability in separation of ATZ from simulated environmental water samples. The presented work has shown tremendous potential for preparing natural spider-web-like molecularly imprinted membranes (MIMs) for selective separation of environment pollutants.

Propolis loaded and genipin-crosslinked PVA/chitosan membranes; characterization properties and cytocompatibility/genotoxicity response for wound dressing applications

Loading propolis by a simple process using genipin as a crosslinking agent and fabrication of a novel PVA/Chitosan-Propolis membrane scaffolds were reported for wound dressing applications. The research is focused on the effects of propolis on characterization properties of membrane such as chemical structure, surface morphology, degradation ratio, crystallinity, hydrophilicity, water uptake capacity, water vapour transmission rate and mechanical aspect. It was noticed that water uptake capacity and hydrophilicity properties of membrane considerably affected by the propolis. By addition of (0.50, % v/v) propolis, the contact angle of the PVA/Chitosan membrane was remarkably decreased from 86.29° ± 3 to 45 ± 2°. 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenylte-trazolium (MTT) bromide test and SEM were used to analyse the cytocompatibility of the membranes and morphology of cells on membrane. The propolis incorporated membrane showed cell proliferation rate 176 ± 13%, 775 ± 1%, and 853 ± 23%, at 24 h, 27 h and 120 h, respectively. SEM images also supported the cell behaviour on membrane. DNA fragmentation was also investigated with genotoxicity test. The studies on the interactions between membranes and MEF cells revealed that the incorporation of propolis into membrane promoted cell proliferation. These overall results presented that propolis incorporated membranes could have potentially appealing application as scaffolds for wound healing applications.

Osteogenesis enhancement using poly (l-lactide-co-d, l-lactide)/poly (vinyl alcohol) nanofibrous scaffolds reinforced by phospho-calcified cellulose nanowhiskers

Electrospun poly (l-lactide-co-d, l-lactide) (PLDLLA)/poly (vinyl alcohol) (PVA) nanofibers were reinforced by various contents (0-1 wt%) of phospho-calcified cellulose nanowhiskers (PCCNWs) as scaffolds in bone applications. The hydrophilicity and rate of hydrolytic degradation of PLDLLA were improved by introducing 10 wt% of PVA. PCCNWs with inherent hydrophilic properties, high aspect ratio, and large elastic modulus enhanced the hydrophilicity, accelerated the rate of degradation, and improved the mechanical properties of the nanofibrous samples. Moreover, calcium phosphate and phosphate functional groups on the surface of PCCNWs possessing act as stimulating agents for cellular activities such as proliferation and differentiation. Besides the physico-chemical properties investigation of PLDLLA/PVA-PCCNWs nanofibrous samples, their cytotoxicity was also studied and they did not show any adverse side effect. Incorporation of PCCNWs (1 wt%) into the PLDLLA/PVA nanofibrous samples showed more enzymatic activities and deposited calcium. The micrograph images of the morphology of human mesenchymal stem cells (hMSCs) cultured on the nanofibrous sample containing 1 wt% of PCCNWs after 14 days of cell differentiation revealed their high potential for bone tissue engineering.