A facile method to synthesize mussel-inspired polydopamine nanospheres as an active template for in situ formation of biomimetic hydroxyapatite

Antimicrobial and Remineralization of Carboxymethyl Chitosan and Xylitol Functionalized Carbon Dots Coating on Orthodontic Brackets

Purpose

During fixed orthodontic treatment, oral hygiene is difficult to ensure and can easily lead to an imbalance in the oral micro-ecological balance. In this study, based on the adhesive properties of polydopamine (PDA) and the good antimicrobial and remineralization properties of carboxymethyl chitosan (CMC) and xylitol (Xy), new nanocomposites with both antimicrobial and remineralization capabilities were prepared to coat on orthodontic brackets.

Methods

Composite carbon dots (CDs) were synthesized using carboxymethyl chitosan and xylitol, we characterized them and the antimicrobial properties of the CMC-Xy-CDs were investigated by co-cultivation with S. mutans in vitro and in vivo. The composite coating was then adhered to the brackets. After the characterization measurements, antibacterial properties against S. mutans and the ability to promote remineralization of isolated teeth were investigated.

Results

Biological studies demonstrated that L929 cells co-cultured with CMC-Xy-CDs did not observe significant cytotoxicity and CMC-Xy-CDs have good biocompatibility. In the adhesive action of PDA, various characterizations have proved that CDs are modified on the brackets surface. In the antibacterial experiment, CMC-Xy-CDs and the adhesive coating on the brackets were found to have better antibacterial performance than the control group, with an antibacterial rate of up to 80%. In the animal experiment, the results of CMC-Xy-CDs promoting the healing of S. mutans infection wound models showed that there was a significant difference at 7d (P < 0.001), indicating that the experimental group had good antibacterial effects. The SEM of teeth after CMC-Xy-CDs promoted remineralization showed that the structure of the tooth surface became dense and some precipitation appeared, and the surface hardness measurement was significantly increased (p<0.0001).

Conclusion

Our study revealed that new nanocomposites with both antimicrobial and remineralization capabilities coated on orthodontic brackets provide a good basis for future clinical applications.

Enhancing Water Lubrication in UHMWPE Using Mesoporous Polydopamine Nanoparticles: A Strategy to Mitigate Frictional Vibration

Establishing a persistent lubrication mechanism and a durable tribo-film on contact surfaces is identified as crucial for improving the tribology and vibration characteristics of polymer materials under water-lubricated conditions. This study focuses on enhancing tribological performance and reducing frictional vibrations in ultrahigh molecular weight polyethylene (UHMWPE) through the incorporation of mesoporous polydopamine (MPDA) nanoparticles. In the experiments, MPDA nanoparticles were synthesized and blended with UHMWPE to create UHMWPE/MPDA composites. The interactions between these composites and zirconia (ZrO2) ceramic balls under water lubrication were examined. The results show that when the MPDA content of the composite is 1.5 wt %, the coefficient of friction and wear rate are reduced by 40% and 52% compared with those of pure UHMWPE, respectively. This notable enhancement helped to mitigate friction-induced vibrations, particularly those caused by intermittent sticking and slipping motions. MPDA nanoparticles were shown to act as reservoirs for water, releasing and replenishing water based on the loading conditions, which sustained continuous water-based lubrication at the composite surfaces. Additionally, the surface deformation behavior of the composite material is significantly weakened, which provides a more stable friction surface. This work introduces a novel approach to enhance the interface stability of polymers in water-lubricated environments, offering guidance for developing advanced materials and reducing friction and wear in engineering applications.

Agarose Cryogels Loaded with Polydopamine Microspheres for Sustainable Wound Care with Enhanced Hemostatic and Antioxidant Properties

Excessive bleeding presents a grave risk to life, especially in scenarios involving deep wounds such as those inflicted by gunshots and accidental stabs. Despite advancements in wound care management, existing commercial hemostatic agents have limitations, necessitating the development of enhanced solutions. In this study, we developed cryogels using agarose and polydopamine microspheres as a hemostatic dressing to effectively manage profuse bleeding. The resulting cryogels demonstrated impressive attributes, such as high absorption capacity (>4000%), shape recovery ability, antioxidant properties, and excellent biocompatibility in mammalian cell lines. Particularly noteworthy was the rapid blood clotting observed in vitro, with the agarose/PDA cryogels achieving complete clotting within just 90 s. Subsequent validation in the rat trauma model further underscored their hemostatic efficacy, with clotting times of 40 and 53 s recorded in tail amputation and liver puncture models, respectively. The porous structure and hydrophilicity of the cryogels facilitated superior blood absorption and retention, while the amine groups of polydopamine played a pivotal role in enhancing blood clotting activity. This study represents a significant step forward in utilizing agarose/polydopamine cryogels as advanced materials for hemostatic wound dressings, promising an impactful contribution to wound therapy.

Polydopamine Applications in Biomedicine and Environmental Science

This manuscript explores the multifaceted applications of polydopamine (PDA) across various scientific and industrial domains. It covers the chemical aspects of PDA and its potential in bone tissue engineering, implant enhancements, cancer treatment, and nanotechnology. The manuscript investigates PDA's roles in tissue engineering, cell culture technologies, surface modifications, drug delivery systems, and sensing techniques. Additionally, it highlights PDA's contributions to microfabrication, nanoengineering, and environmental applications. Through detailed testing and assessment, the study identifies limitations in PDA-related research, such as synthesis complexity, incomplete mechanistic understanding, and biocompatibility variability. It also proposes future research directions aimed at improving synthesis techniques, expanding biomedical applications, and enhancing sensing technologies to optimize PDA's efficacy and scalability.

Sensory Nerve Regulation via H3K27 Demethylation Revealed in Akermanite Composite Microspheres Repairing Maxillofacial Bone Defect

Maxillofacial bone defects exhibit intricate anatomy and irregular morphology, presenting challenges for effective treatment. This study aimed to address these challenges by developing an injectable bioactive composite microsphere, termed D-P-Ak (polydopamine-PLGA-akermanite), designed to fit within the defect site while minimizing injury. The D-P-Ak microspheres biodegraded gradually, releasing calcium, magnesium, and silicon ions, which, notably, not only directly stimulated the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) but also activated sensory nerve cells to secrete calcitonin gene-related peptide (CGRP), a key factor in bone repair. Moreover, the released CGRP enhanced the osteogenic differentiation of BMSCs through epigenetic methylation modification. Specifically, inhibition of EZH2 and enhancement of KDM6A reduced the trimethylation level of histone 3 at lysine 27 (H3K27), thereby activating the transcription of osteogenic genes such as Runx2 and Osx. The efficacy of the bioactive microspheres in bone repair is validated in a rat mandibular defect model, demonstrating that peripheral nerve response facilitates bone regeneration through epigenetic modification. These findings illuminated a novel strategy for constructing neuroactive osteo-inductive biomaterials with potential for further clinical applications.

Bovine serum albumin-modified 3D printed alginate dialdehyde-gelatin scaffolds incorporating polydopamine/SiO2-CaO nanoparticles for bone regeneration

Three-dimensional (3D) printing allows precise manufacturing of bone scaffolds for patient-specific applications and is one of the most recently developed and implemented technologies. In this study, bilayer and multimaterial alginate dialdehyde-gelatin (ADA-GEL) scaffolds incorporating polydopamine (PDA)/SiO2-CaO nanoparticle complexes were 3D printed using a pneumatic extrusion-based 3D printing technology and further modified on the surface with bovine serum albumin (BSA) for application in bone regeneration. The morphology, chemistry, and in vitro bioactivity of PDA/SiO2-CaO nanoparticle complexes were characterized (n = 3) and compared with those of mesoporous SiO2-CaO nanoparticles. Successful deposition of the PDA layer on the surface of the SiO2-CaO nanoparticles allowed better dispersion in a liquid medium and showed enhanced bioactivity. Rheological studies (n = 3) of ADA-GEL inks consisting of PDA/SiO2-CaO nanoparticle complexes showed results that may indicate better injectability and printability behavior compared to ADA-GEL inks incorporating unmodified nanoparticles. Microscopic observations of 3D printed scaffolds revealed that PDA/SiO2-CaO nanoparticle complexes introduced additional topography onto the surface of 3D printed scaffolds. Additionally, the modified scaffolds were mechanically stable and elastic, closely mimicking the properties of natural bone. Furthermore, protein-coated bilayer scaffolds displayed controllable absorption and biodegradation, enhanced bioactivity, MC3T3-E1 cell adhesion, proliferation, and higher alkaline phosphatase (ALP) activity (n = 3) compared to unmodified scaffolds. Consequently, the present results confirm that ADA-GEL scaffolds incorporating PDA/SiO2-CaO nanoparticle complexes modified with BSA offer a promising approach for bone regeneration applications.

Synthesis, spectroscopy, band gap energy and electrical conductivity of poly(dopamine-co-aniline) copolymer

Copolymerization is used to improve the solubility and processability of polymers and copolymers includes the individual properties of homopolymer. In this study, the poly(dopamine-co-aniline) (poly(DA-co-ANI) copolymer was synthesized and the UV-vis. absorption, optical band gap energy, fluorescence, FT-IR, SEM-EDS, MALDI-TOF-MS, XRD and electrical conductivity have been investigated. The obtained results for the poly(DA-co-ANI) copolymer were compared with the PDA and PANI homopolymers. It was observed that the poly(DA-co-ANI copolymer is soluble easily in NMP and DMF solvents. The optical band gap energy of the poly(DA-co-ANI) copolymer film were calculated. as 1.00 eV with favorable indirect transition. The poly(DA-co-ANI) copolymer showed the FL emission maximum bands at 390 and 533 nm wavelengths. It was observed from the SEM images that the poly(DA-co-ANI) has 0-1500 nm crystalline rectangular particles prepared in acidic media and 0-600 nm amorphous particles prepared in basic media. The electrical conductivity of the poly(DA-co-ANI) was 1.35 × 10-6 S/cm. In the MALDI-TOF-MS measurements, the number-average molecular weight of the copolymer was found as 2628 Da with a distribution up to 5500 Da. The poly(DA-co-ANI) copolymer, soluble in NMP and DMF solvents and with a low optical band gap energy can be utilized as optical, fluorescent, and semi-conductive material in biomedical applications.

Polydopamine and calcium functionalized fiber carrier for enhancing microbial attachment and Cr(VI) resistance

The formation of biofilm determines the performance and stability of biofilm system. Increasing the hydrophilicity of the carrier surface could efficiently accelerate the attachment and growth of microorganisms. Here, the surface of polypropylene (PP) fiber carrier was modified with polydopamine (PDA) and calcium (Ca(II)) to enhance microbial attachment and toxicity resistance. The results of surface characteristic confirmed the self-polymerization of PDA and the chelation mechanism of Ca(II). Subsequently, the biofilm formation experiments were conducted in sequencing batch biofilm reactors using both normal and chromium-containing wastewater. The biofilm on the surface of the modified carrier exhibited better nitrogen removal and Cr(VI) reduction ability. The biomass of the modified carrier was significantly increased, and the maximum microbial attachment amounts in normal wastewater and chrome-containing wastewater were 1153.34 and 511.78 mg/g carrier, respectively. Furthermore, the confocal laser scanning microscope (CLSM) indicated that the modified carrier coated with PDA and Ca(II) were both biocompatible, and the cell activity was significantly increased. 16S rRNA sequencing results showed that the modified carrier efficiently enriched both denitrification bacteria (Thauera and Flavobacterium) and chrome-reducing bacteria (Simplicispira and Arenimonas) to improve system stability and Cr(VI) resistance. Microbial phenotype prediction based on BugBase analysis further verified the enrichment effect of modified carriers on microorganisms responsible for biofilm formation and oxidative stress resistance. Overall, this work proposed a novel functional carrier that could provide references for advancing the application of biofilm systems in wastewater treatment.

Biosynthesis of Quercetin-Loaded Melanin Nanoparticles for Improved Antioxidant Activity, Photothermal Antimicrobial, and NIR/pH Dual-Responsive Drug Release

Quercetin (QCT) is a promising dose-dependent nutraceutical that usually suffers from poor water solubility and low bioavailability issues. In this work, a novel QCT-loaded nanoscale delivery system was constructed based on the oxidative self-polymerization of melanin (Q@MNPs). The FT-IR, XRD, and Zeta potential analyses confirmed that QCT was successfully absorbed on the melanin nanoparticles (MNPs) via Π-Π and hydrogen bonding interactions. The encapsulation efficiency and particle size of Q@MNPs were 43.78% and 26.68 nm, respectively. Q@MNPs improved the thermal stability of QCT and the antioxidant properties in comparison to MNPs. Meanwhile, Q@MNPs presented fantastic photothermal conversion capacity and stability triggered by the NIR laser, which significantly enhanced the antibacterial capability with a sterilization rate of more than 98% against E. coli and S. aureus. More importantly, Q@MNPs exhibited NIR/pH dual-responsive drug release behavior and good biocompatibility (at concentrations of < 100 μg/mL). Thus, Q@MNPs show promising prospects for flavonoid delivery.

Fabrication of versatile poly(xylitol sebacate)-co-poly(ethylene glycol) hydrogels through multifunctional crosslinkers and dynamic bonds for wound healing

Poly(polyol sebacate) (PPS) polymer family has been recognized as promising biomaterials for biomedical applications with their characteristics of easy production, elasticity, biodegradation, and cytocompatibility. Poly(xylitol sebacate)-co-poly(ethylene glycol) (PXS-co-PEG) has been developed to fabricate PPS-based hydrogels; however, current PXS-co-PEG hydrogels presented limited properties and functions due to the limitations of the crosslinkers and crosslinking chemistry used in the hydrogel formation. Here, we fabricate a new type of PXS-co-PEG hydrogels through the use of multifunctional crosslinkers as well as dynamic bonds. In our design, polyethyleneimine-polydopamine (PEI-PDA) macromers are utilized to crosslink aldehyde-functionalized PXS-co-PEG (APP) through imine bonds and hydrogen bonds. PEI-PDA/APP hydrogels present multiple functional properties (e.g., fluorescent, elastomeric, biodegradable, self-healing, bioadhesive, antioxidant, and antibacterial behaviors). These properties of PEI-PDA/APP hydrogels can be fine-tuned by changing the PDA grafting degrees in the PEI-PDA crosslinkers. Most importantly, PEI-PDA/APP hydrogels are considered promising wound dressings to promote tissue remodeling and prevent bacterial infection in vivo. Taken together, PEI-PDA/APP hydrogels have been demonstrated as versatile biomaterials to provide multiple tailorable properties and desirable functions to expand the utility of PPS-based hydrogels for advanced biomedical applications. STATEMENT OF SIGNIFICANCE: Various strategies have been developed to fabricate poly(polyol sebacate) (PPS)-based hydrogels. However, current PPS-based hydrogels present limited properties and functions due to the limitations of the crosslinkers and crosslinking chemistry used in the hydrogel formation. This work describes that co-engineering crosslinkers and interfacial crosslinking is a promising approach to synthesizing a new type of poly(xylitol sebacate)-co-poly(ethylene glycol) (PXS-co-PEG) hydrogels as multifunctional hydrogels to expand the utility of PPS-based hydrogels for advanced biomedical applications. The fabricated hydrogels present multiple functional properties (e.g., fluorescent, biodegradable, elastomeric, self-healing, bioadhesive, antioxidative, and antibacterial), and these properties can be fine-tuned by the defined crosslinkers. The fabricated hydrogels are also used as promising wound dressing biomaterials to exhibit promoted tissue remodeling and prevent bacterial infection in vivo.

Hydroxyapatite-based carriers for tumor targeting therapy

At present, targeted drug delivery is regarded as the most effective means of tumor treatment, overcoming the lack of conventional chemotherapeutics that are difficult to reach or enter into cancer cells. Hydroxyapatite (HAP) is the main component of biological hard tissue, which can be regarded as a suitable drug carrier due to its biocompatibility, nontoxicity, biodegradation, and absorbability. This review focuses on the cutting edge of HAP as a drug carrier in targeted drug delivery systems. HAP-based carriers can be obtained by doping, modification, and combination, which benefit to improve the loading efficiency of drugs and the response sensitivity of the microenvironment in the synthesis process. The drug adsorbed or in situ loaded on HAP-based carriers can achieve targeted drug delivery and precise treatment through the guidance of the in vivo microenvironment and the stimulation of the in vitro response. In addition, HAP-based drug carriers can improve the cellular uptake rate of drugs to achieve a higher treatment effect. These advantages revealed the promising potential of HAP-based carriers from the perspective of targeted drug delivery for tumor treatment.

Mussel-inspired polydopamine decorated silane modified-electroconductive gelatin-PEDOT:PSS scaffolds for bone regeneration

This study seeks to simulate both the chemistry and piezoelectricity of bone by synthesizing electroconductive silane-modified gelatin-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) scaffolds using the freeze drying technique. In order to enhance hydrophilicity, cell interaction, and biomineralization, the scaffolds were functionalized with polydopamine (PDA) inspired by mussels. Physicochemical, electrical, and mechanical analyses were conducted on the scaffolds, as well as in vitro evaluations using the osteosarcoma cell line MG-63. It was found that scaffolds had interconnected porous structures, so the PDA layer formation reduced the size of pores while maintaining scaffold uniformity. PDA functionalization reduced the electrical resistance of the constructs while improving their hydrophilicity, compressive strength, and modulus. As a result of the PDA functionalization and the use of silane coupling agents, higher stability and durability were achieved as well as an improvement in biomineralization capability after being soaked in SBF solution for a month. Additionally, the PDA coating enabled the constructs to enhance viability, adhesion, and proliferation of MG-63 cells, as well as to express alkaline phosphatase and deposit HA, indicating that scaffolds can be used for bone regeneration. Therefore, the PDA-coated scaffolds developed in this study and the non-toxic performance of PEDOT:PSS present a promising approach for further in vitro and in vivo studies.

Nonporous versus Mesoporous Bioinspired Polydopamine Nanoparticles for Skin Drug Delivery

The use of polydopamine-based bioinspired nanomaterials has shed new light on advanced drug delivery arising from their efficient surface functionalization. More recently, the polydopamine self-assemblies formed in two different modalities, i.e., nonporous and mesoporous nanoparticles, have begun to attract attention due to their expedient and versatile properties. However, their possibility for use in dermal drug delivery for local therapy, as well as their interaction with the skin, has not yet been demonstrated. Our study aimed to compare and explore the feasibility of the self-assembled nonporous polydopamine nanoparticles (PDA) and mesoporous polydopamine nanoparticles (mPDA) for local skin drug delivery. The formation of the PDA and mPDA structures was confirmed by the UV-vis-NIR absorption spectrum, the Fourier transform infrared spectroscopy, and the nitrogen adsorption/desorption isotherms. Using retinoic acid (RA) as the model drug, their effects on drug loading, release, photostability, skin penetration, and radical scavenging were investigated. Laser scanning confocal microscopy (LSCM) and hematoxylin and eosin (H&E) were introduced to probe their delivery routes and possible interaction with the skin. The results indicated that both PDA and mPDA could reduce the photodegradation of RA, and mPDA showed significantly better radical scavenging activity and drug loading capacity. The ex vivo permeation study revealed that both PDA and mPDA significantly enhanced the delivery of RA into the deep skin layers by comparison with the RA solution, in which follicular and intercellular pathways existed, and alteration in the structure of stratum corneum was observed. In light of drug loading capacity, size controllability, physical stability, as well as radical scavenging activity, mPDA was more preferable due to the improvement of these factors. This work demonstrated the feasibility and promising application of PDA and mPDA nanoparticles for dermal drug delivery, and the comparative concept of these two types of biomaterials can provide implications for their use in other fields.

Dopamine-Assisted Modification of Polypropylene Film to Attain Hydrophilic Mineral-Rich Surfaces

The presented study focuses on the modification of polypropylene (PP) film with tetraethyl orthosilicate (TEOS) under heterogeneous conditions via polydopamine/polyethylene imine (PDA/PEI) chemistry using a facile dip-coating procedure to attain hydrophilic mineral-rich surfaces. Thus, the resulting PP-based films were further immersed in ion-rich simulated body fluid (SBF) to deposit Ca-based minerals onto the film's surfaces efficiently. In addition, the chemical reaction mechanism on PP film was proposed, and mineralisation potential inspected by determination of functional groups of deposits, zeta potential, hydrophilicity and surface morphology/topography using Fourier transform infrared (FTIR) spectroscopy, streaming potential, water contact angle (WCA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained results show the improved wettability of samples on account of PDA inclusion (WCA was reduced from 103° for pure PP film to 28° for PDA-modified film), as well as the presence of functional groups, due to the PDA/PEI/TEOS surface functionalisation, increased the ability of minerals to nucleate on the PP film's surface when it was exposed to an SBF medium. Moreover, the higher surface roughness due to the silica coatings influenced the enhanced anchoring and attachment of calcium phosphate (CaP), revealing the potential of such a facile approach to modify the chemically inert PP films, being of particular interest in different fields, including regenerative medicine.

Polydopamine/polypyrrole-modified graphite felt enhances biocompatibility for electroactive bacteria and power density of microbial fuel cell

The interactions between the microbes and the surface of an anode play an important role in capturing the respiratory electrons from bacteria in a microbial fuel cell (MFC). The chemical and electrochemical characteristics of the carbon material affect biofilm growth and direct electron transfer in MFCs. This study examined the electrodeposition of polydopamine (PDA) and polypyrrole (PPY) on graphite felt electrode (GF). The MFC with the modified PDA/PPY-GF reached 920 mW/m², which was 1.5, 1.17, and 1.18 times higher than those of the GF, PDA-GF, and PPY-GF, respectively. PDA has superior hydrophilicity and adhesive force biofilm formation, while PPY provides electrochemically active sites for microbial electron transfer. Raman spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area measurements, and contact angle analysis revealed the enhanced physicochemical properties of the carbon electrode. These results show that co-doped PDA/PPY provides a strategy for electroactive biofilm development and improves the bioelectrochemical performance in realistic MFC reactors.

A critical review on polydopamine surface-modified scaffolds in musculoskeletal regeneration

Increasing concern about age-related diseases, particularly musculoskeletal injuries and orthopedic conditions, highlights the need for strategies such as tissue engineering to address them. Surface modification has been developed to create pro-healing interfaces, personalize scaffolds and provide novel medicines. Polydopamine, a mussel-inspired adhesive polymer with highly reactive functional groups that adhere to nearly all substrates, has gained attention in surface modification strategies for biomaterials. Polydopamine was primarily developed to modify surfaces, but its effectiveness has opened up promising approaches for further applications in bioengineering as carriers and nanoparticles. This review focuses on the recent discoveries of the role of polydopamine as a surface coating material, with focus on the properties that make it suitable for tackling musculoskeletal disorders. We report the evolution of using it in research, and discuss papers involving the progress of this field. The current research on the role of polydopamine in bone, cartilage, muscle, nerve, and tendon regeneration is discussed, thus giving comprehensive overview about the function of polydopamine both in-vitro and in-vivo. Finally, the report concludes presenting the critical challenges that must be addressed for the clinical translation of this biomaterial while exploring future perspectives and research opportunities in this area.

Advanced materials for enamel remineralization

Dental caries, a chronic and irreversible disease caused by caries-causing bacteria, has been listed as one of the three major human diseases to be prevented and treated. Therefore, it is critical to effectively stop the development of enamel caries. Remineralization treatment can control the progression of caries by inhibiting and reversing enamel demineralization at an early stage. In this process, functional materials guide the deposition of minerals on the damaged enamel, and the structure and hardness of the enamel are then restored. These remineralization materials have great potential for clinical application. In this review, advanced materials for enamel remineralization were briefly summarized, furthermore, an outlook on the perspective of remineralization materials were addressed.

The effects of process parameters on polydopamine coatings employed in tissue engineering applications

The biomaterials’ success within the tissue engineering field is hinged on the capability to regulate tissue and cell responses, comprising cellular adhesion, as well as repair and immune processes’ induction. In an attempt to enhance and fulfill these biomaterials’ functions, scholars have been inspired by nature; in this regard, surface modification via coating the biomaterials with polydopamine is one of the most successful inspirations endowing the biomaterials with surface adhesive properties. By employing this approach, favorable results have been achieved in various tissue engineering-related experiments, a significant one of which is the more rapid cellular growth observed on the polydopamine-coated substrates compared to the untreated ones; nonetheless, some considerations regarding polydopamine-coated surfaces should be taken into account to control the ultimate outcomes. In this mini-review, the importance of coatings in the tissue engineering field, the different types of surfaces requiring coatings, the significance of polydopamine coatings, critical factors affecting the result of the coating procedure, and recent investigations concerning applications of polydopamine-coated biomaterials in tissue engineering are thoroughly discussed.

Mussel-inspired polydopamine decorated alginate dialdehyde-gelatin 3D printed scaffolds for bone tissue engineering application

This study utilized extrusion-based 3D printing technology to fabricate calcium-cross-linked alginate dialdehyde-gelatin scaffolds for bone regeneration. The surface of polymeric constructs was modified with mussel-derived polydopamine (PDA) in order to induce biomineralization, increase hydrophilicity, and enhance cell interactions. Microscopic observations revealed that the PDA layer homogeneously coated the surface and did not appear to induce any distinct change in the microstructure of the scaffolds. The PDA-functionalized scaffolds were more mechanically stable (compression strength of 0.69 ± 0.02 MPa) and hydrophilic (contact angle of 26) than non-modified scaffolds. PDA-decorated ADA-GEL scaffolds demonstrated greater durability. As result of the 18-days immersion in simulated body fluid solution, the PDA-coated scaffolds showed satisfactory biomineralization. Based on theoretical energy analysis, it was shown that the scaffolds coated with PDA interact spontaneously with osteocalcin and osteomodulin (binding energy values of -35.95 kJ mol-1 and -46.39 kJ mol-1, respectively), resulting in the formation of a protein layer on the surface, suggesting applications in bone repair. PDA-coated ADA-GEL scaffolds are capable of supporting osteosarcoma MG-63 cell adhesion, viability (140.18% after 7 days), and proliferation. In addition to increased alkaline phosphatase secretion, osteoimage intensity also increased, indicating that the scaffolds could potentially induce bone regeneration. As a consequence, the present results confirm that 3D printed PDA-coated scaffolds constitute an intriguing novel approach for bone tissue engineering.

Mussel-Inspired Polydopamine-Based Multilayered Coatings for Enhanced Bone Formation

Repairing bone defects remains a challenge in clinical practice and the application of artificial scaffolds can enhance local bone formation, but the function of unmodified scaffolds is limited. Considering different application scenarios, the scaffolds should be multifunctionalized to meet specific demands. Inspired by the superior adhesive property of mussels, polydopamine (PDA) has attracted extensive attention due to its universal capacity to assemble on all biomaterials and promote further adsorption of multiple external components to form PDA-based multilayered coatings with multifunctional property, which can induce synergistic enhancement of new bone formation, such as immunomodulation, angiogenesis, antibiosis and antitumor property. This review will summarize mussel-inspired PDA-based multilayered coatings for enhanced bone formation, including formation mechanism and biofunction of PDA coating, as well as different functional components. The synergistic enhancement of multiple functions for better bone formation will also be discussed. This review will inspire the design and fabrication of PDA-based multilayered coatings for different application scenarios and promote deeper understanding of their effect on bone formation, but more efforts should be made to achieve clinical translation. On this basis, we present a critical conclusion, and forecast the prospects of PDA-based multilayered coatings for bone regeneration.

A Facile Method to Synthesize 3D Pomegranate-like Polydopamine Microspheres

Nanospheres have found versatile applications in the biomedical field; however, their possible harmful effects on immune and inflammatory systems are also a crucial concern. Inspired by a pomegranate structure, we demonstrated a novel structure for the nanostructured microspheres to overcome the drawbacks of nanospheres without compromising their merits. In this study, 3D pomegranate-like polydopamine microspheres (PDAMS) were synthesized by self-oxidative polymerization of dopamine hydrochloride. Herein, controlling the pH during polymerization led to synthesizing homogeneous agglomerated nano-sized spheres (400–2000 nm) and finally forming tunable and monodisperse micron-sized particles (21 µm) with uniform spherical shape porous microstructure. PDAMS interaction with the potential targets, Bone morphogenetic protein-2 (BMP2), Decorin, and Matrilin-1, was investigated via molecular calculations. Theoretical energy analysis revealed that PDAMS interaction with BMP2, Decorin, and Matrilin-1 is spontaneous, so that a protein layer formation on the PDAMS surface suggests application in bone and cartilage repair. It was also observed that PDAMS presented in-vitro degradation within 4 weeks. Here, disappearance of the UV-VIS spectrum peak at 280 nm is accompanied by the degradation of catechol groups. Pomegranate-like PDAMS support the biomimetic formation of hydroxyapatite-like layers, making them appropriate candidates for hard tissue applications. Herein, the appearance of peaks in XRD spectrum at 31.37, 39.57, 45.21, and 50.13° attributed to hydroxyapatite-like layers formation. All these results demonstrated that self-oxidative polymerization under a controllable pH can be a green and straightforward technique for preparing the pomegranate-like PDAMS and providing an innovative basis for further pre-clinical and clinical investigations.

Polydopamine nanospheres coated with bovine serum albumin permit enhanced cell differentiation: fundamental mechanism and practical application for protein coating formation

Protein coating is a strategy for modifying and improving the surface functional properties of nanomaterials. However, the underlying mechanism behind protein coating formation, which is essential for its practical applications, remains largely unknown. Herein, we investigate the fundamental molecular mechanism of protein coating formation. Polydopamine nanospheres (PDANS) coated with bovine serum albumin (BSA) are examined in this study due to their wide biomedical potential. Our results demonstrate that BSAs can flexibly bind to PDANS and maintain their structural dynamicity. Our findings unveil that regular structure formation arises from BSAs lateral interactions via electrostatic forces. Notably, the protein coating modified PDANS surface enhances cell adhesion and proliferation as well as osteogenic differentiation. Such an enhancement is attributed to complementary surface properties provided by the dynamic PDANS-BSA complex and regular structure caused by BSA-BSA interactions in protein coating formation. This study provides a fundamental understanding of the molecular mechanism of protein coating formation, which facilitates the further development of functional protein-coated nanomaterials and guides the bioengineering decision making for biomedical applications, especially in bone tissue engineering.

A polydopamine-assisted strontium-substituted apatite coating for titanium promotes osteogenesis and angiogenesis via FAK/MAPK and PI3K/AKT signaling pathways

Early osteointegration is essential for biomedical implants. Surface modifications can significantly compensate for an implant's lack of biocompatibility and osteo-differentiation. They can also be designed to promote angiogenesis in order to assist osteogenesis and ultimately facilitate bone regeneration. In this study, a polydopamine-assisted strontium-substituted apatite coating (Ti@PDA + SrHA) was fabricated on a multifunctional titanium implant to induce both angiogenic and osteogenic abilities for rapid osseointegration. Polydopamine and Sr-substituted hydroxyapatite were coated on the implant through biomineralization. The in vitro results showed that Ti@PDA + SrHA improved cell adhesion and increased the proliferation of rat bone marrow-derived mesenchymal stem cells (rBMSCs) and human umbilical vein endothelial cells (HUVECs). Ti@PDA + SrHA upregulated the expression of ALP activity and osteogenic genes in rBMSCs and elevated angiogenic genes in both rBMSCs and HUVECs. Mechanically, the FAK/MAPK signaling pathway was activated in rBMSCs, and the PI3K/AKT signaling pathway was activated in both rBMSCs and HUVECs. Consistent with these findings, Ti@PDA + SrHA accelerated new bone formation and rapid osseointegration in the femoral condyle implantation study with good stability. Overall, we fabricated a multifunctional biocompatible implant with better angiogenic and osteogenic performance compared to the non-coated implant.

Mechanistically Scoping Cell-Free and Cell-Dependent Artificial Scaffolds in Rebuilding Skeletal and Dental Hard Tissues

Rebuilding mineralized tissues in skeletal and dental systems remains costly and challenging. Despite numerous demands and heavy clinical burden over the world, sources of autografts, allografts, and xenografts are far limited, along with massive risks including viral infections, ethic crisis, and so on. Per such dilemma, artificial scaffolds have emerged to provide efficient alternatives. To date, cell-free biomimetic mineralization (BM) and cell-dependent scaffolds have both demonstrated promising capabilities of regenerating mineralized tissues. However, BM and cell-dependent scaffolds have distinctive mechanisms for mineral genesis, which makes them methodically, synthetically, and functionally disparate. Herein, these two strategies in regenerative dentistry and orthopedics are systematically summarized at the level of mechanisms. For BM, methodological and theoretical advances are focused upon; and meanwhile, for cell-dependent scaffolds, it is demonstrated how scaffolds orchestrate osteogenic cell fate. The summary of the experimental advances and clinical progress will endow researchers with mechanistic understandings of artificial scaffolds in rebuilding hard tissues, by which better clinical choices and research directions may be approached.

2-Dodecylmalonic acid-mediated synthesis of mineralized hydroxyapatite amicable for bone cell growth on orthopaedic implant

The present study illustrates the use of 2-dodecylmalonic acid (MA) as a template in biomineralization-inspired synthesis of hydroxyapatite nanoparticles (HANPs). HANPs synthesized in presence of various concentrations of MA displayed varying particle size and shape. The smallest particle size (22-27 nm) was obtained for MA₂-HANP synthesized in presence of 37 µM MA. The critical micelle concentration (CMC) for MA at pH 9.0 relevant for mineralization was ∼35 µM. AFM analysis revealed that at a low concentration of 10 µM and pH 9.0, MA could generate oblong-shaped aggregates. At 40 µM, comparable to the concentration used to generate MA₂-HANP, the amphiphile self-assembled to form a spherical soft scaffold, which likely regulated spatial confinement of ions during mineralization and generated small size HANPs. Osteoblast-like MG-63 cells seeded on titanium wire (TW) coated with MA₂-HANP-incorporated collagen type I (H-TW) displayed enhanced cell proliferation, high expression of osteogenic differentiation marker genes (Col I, ALP, OCN and Runx2) and copious calcium mineral deposition after 14 days of growth. The nuanced role of the self-assembly process of an amphiphilic template in HANP mineralization unravelled in the present study can guide future scaffold design for biomineralization-inspired synthesis of HANPs tailored for bone tissue engineering applications.

Research Progress on Polydopamine Nanoparticles for Tissue Engineering

Tissue engineering is an interdisciplinary field that aims to develop biological substitutes for the replacement, repair, or enhancement of tissue function. The physical and chemical characteristics of biomaterials exert a profound influence on the biological responses and the following biofunction. Nanostructured coatings have been widely applied as an effective surface modification strategy to improve the bioactivity of biomaterials. Especially, polydopamine and polydopamine-derived nanoparticles are found with excessive adhesiveness, redox activity, photothermal conversion capacity, paramagnetism and conductivity other than excellent biocompatibility, and hydrophilicity. In this article, advances about polydopamine nanoparticles in tissue engineering applications are reviewed, including the repair of bone, cartilage, skin, heart, and nerve, to provide strategies for future biomaterial design.

Catalytical feature of optical nanoprobes of boron nitride quantum dots in the presence of Cu2+ for the determination of dopamine

Monitoring the concentration of dopamine (DA) is vital for preventing and diagnosing DA related diseases. In contrast to the traditional sensing methods for DA, in which direct or indirect effects on the optical probes are often recorded, a novel sensing concept is disclosed based on as a result of the in situ formation of polydopamine (PDA) originating from the synergetic effect between boron nitride quantum dots (BNQDs) and Cu2+. In the co-presence of BNQDs and Cu2+, DA was catalytically oxidized to PDA, accompanied by an obvious color change from colorless to brown. In contrast to previous reports, in which BNQDs have been employed as an optical probe, herein, the BNQDs not only acted as the optical energy donor, but also as the catalysts for the formation of PDA. The quenching efficiency resulting from the inner filter effect and the electron transfer between the BNQDs and PDA was directly proportional to the concentration of DA, ranging linearly from 2 to 80 μM with a limit of detection of 0.49 μM. The present system exhibited an outstanding selectivity for DA among other interfering coexisting biomolecules. Furthermore, the practical application of the proposed platform was verified by assaying DA in human plasma samples, and satisfactory recoveries ranging from 101.24% to 111.98% were obtained. With the satisfactory reliability, repeatability and stability, the proposed simple sensor showed significant potential for use in DA detection in other biomedical applications.

Probiotic bacteria cell surface-associated protein mineralized hydroxyapatite incorporated in porous scaffold: In vitro evaluation for bone cell growth and differentiation

There is a high demand for synthesis of biocompatible hydroxyapatite nanoparticle (HANP), which is a key component in bone tissue engineering scaffolds. The present study describes a facile route of HANP synthesis through mineralization of the cell surface-associated protein (CSP) from the human probiotic lactic acid bacteria (LAB) Lactobacillus rhamnosus GG. CSP extract from the LAB (consisting of ~66 kDa, ~47 kDa, ~40 kDa and ~25 kDa protein) was mineralized to yield spindle-shaped HANPs having an average particle length of 371 nm as evidenced in FETEM analysis. CSP-mineralized HANPs (CSP-HANPs) were characterized by FTIR and BET analysis, while XRD and SAED analysis indicated their crystalline nature. Mechanistic studies suggested the key role of ~25 kDa CSP (F4SP) in mineralization. In contrast to CSP-HANPs, F4SP-mineralized crystalline HA was plate-shaped having an average length of 1.68 μm and breadth of 0.95 μm. HANP mineralization at the whole-cell (WC) level resulted in clusters of aggregated HANPs (WC-HANPs) adhering onto L. rhamnosus GG cells as evident in FETEM, FESEM and AFM analysis. FETEM analysis revealed that the desorbed WC-HANPs recovered by cell lysis were needle-shaped, with a particle size distribution of 70-110 nm. Given that CSP-HANPs were non-toxic to cultured HEK 293 cells and osteoblast-like MG-63 cells, chitosan-gelatin (CG) scaffold incorporated with 15% w/v CSP-HANP (H-CG) was generated and tested for bone cell growth. H-CG exhibited a favorable pore size distribution (160-230 μm), overall porosity (~84%) and biodegradation profile. H-CG scaffold was conducive to osteogenesis and rendered enhanced proliferation, alkaline phosphatase (ALP) activity, calcium mineralization and heightened marker gene expression (ALP, Col I, Runx2 and OCN) in seeded MG-63 cells. CSP sourced from a safe probiotic LAB is thus a viable and effective mineralization template for synthesis of biocompatible HANPs that can be leveraged for bone tissue engineering applications.

Polyamidoamine Dendrimers Decorated Multifunctional Polydopamine Nanoparticles for Targeted Chemo- and Photothermal Therapy of Liver Cancer Model

The development of multifunctional drug delivery systems combining two or more nanoparticle-mediated therapies for efficient cancer treatment is highly desired. To face this challenge, a photothermally active polydopamine (PDA) nanoparticle-based platform was designed for the loading of chemotherapeutic drug and targeting of cancer cells. PDA spheres were first functionalized with polyamidoamine (PAMAM) dendrimers followed by the conjugation with polyethylene glycol (PEG) moieties and folic acid (FA) targeting ligand. The anticancer drug doxorubicin (DOX) was then absorbed on the particle surface. We performed the physico-chemical characterization of this versatile material and we assessed further its possible application in chemo- and photothermal therapy using liver cancer cell model. These nanoparticles exhibited high near-infrared photothermal conversion efficacy and allowed for loading of the drug, which upon release in specifically targeted cancer cells suppressed their growth. Using cell proliferation, membrane damage, apoptosis, and oxidative stress assays we demonstrated high performance of this nanosystem in cancer cell death induction, providing a novel promising approach for cancer therapy.

Surface modification of a three-dimensional polycaprolactone scaffold by polydopamine, biomineralization, and BMP-2 immobilization for potential bone tissue applications

Three-dimensional (3D) bioprinting is a free-form fabrication technique enabling fine feature control for tissue engineering applications. Especially, 3D scaffolds capable of supporting cell attachment, proliferation, and osteogenic differentiation are a prerequisite for bone tissue regeneration. Herein, we elaborated this approach to produce a 3D polycaprolactone (PCL) scaffold with long-term osteogenic activity. Specifically, we coated polydopamine (PDA) on 3D PCL scaffolds, subsequently deposited hydroxyapatite (HA) nanoparticles via biomimetic mineralization, and finally immobilized bone morphogenetic protein-2 (BMP-2). Material properties were characterized and compared with various 3D scaffolds, including PCL, PDA-coated PCL (PCL/PDA), and PDA-coated and HA-deposited PCL (PCL/PDA/HA). In vitro cell culture studies with osteoblasts revealed that the PCL/PDA/HA scaffolds immobilized with BMP-2 showed long-term retention of BMP-2 (for up to 21 days) and significantly increased osteoblast proliferation and osteogenic differentiation, as evidenced by metabolic activity, alkaline phosphatase activity, and calcium deposition. We believe that this multifunctional osteogenic 3D scaffold will be useful for bone tissue engineering applications.

Antineoplastic behavior of polydopamine nanoparticles prepared in different water/alcohol media

Polydopamine nanoparticles (PD NPs) have been synthesized in the present work through the oxidative polymerization of dopamine in aqueous media containing five different types of alcohol in a constant solvent volume ratio. We have shown that the type of alcohol, along with the ammonium hydroxide concentration used in the synthesis process, conditions particle size. Additionally, it has been found that the type of alcohol employed influences the well-known capacity of polydopamine nanoparticles to adsorb iron. As a consequence, since a ferroptosis-like mechanism may account for the cytotoxicity of these nanoparticles, the type of alcohol could also have a determining role in their antineoplastic activity. Here, the existence of a correlation between the ability of polydopamine nanoparticles to load Fe³⁺ and their toxic effect on breast cancer cells has been proven. For instance, nanoparticles synthesized using 2-propanol adsorbed more Fe³⁺ and had the greatest capacity to reduce breast tumor cell viability. Moreover, none of the nanoparticle synthesized with the different alcohols significantly decreased normal cell survival. Cancer cells present greater iron-dependence than healthy cells and this fact may explain why polydopamine nanoparticles toxicity, in which Fenton chemistry could be implicated, seems tumor-specific.

Strategies for Using Polydopamine to Induce Biomineralization of Hydroxyapatite on Implant Materials for Bone Tissue Engineering

In the field of tissue engineering, there are several issues to consider when designing biomaterials for implants, including cellular interaction, good biocompatibility, and biochemical activity. Biomimetic mineralization has gained considerable attention as an emerging approach for the synthesis of biocompatible materials with complex shapes, categorized organization, controlled shape, and size in aqueous environments. Understanding biomineralization strategies could enhance opportunities for novel biomimetic mineralization approaches. In this regard, mussel-inspired biomaterials have recently attracted many researchers due to appealing features, such as strong adhesive properties on moist surfaces, improved cell adhesion, and immobilization of bioactive molecules via catechol chemistry. This molecular designed approach has been a key point in combining new functionalities into accessible biomaterials for biomedical applications. Polydopamine (PDA) has emerged as a promising material for biomaterial functionalization, considering its simple molecular structure, independence of target materials, cell interactions for adhesion, and robust reactivity for resulting functionalization. In this review, we highlight the strategies for using PDA to induce the biomineralization of hydroxyapatite (HA) on the surface of various implant materials with good mechanical strength and corrosion resistance. We also discuss the interactions between the PDA-HA coating, and several cell types that are intricate in many biomedical applications, involving bone defect repair, bone regeneration, cell attachment, and antibacterial activity.

Advances and trends of hydrogel therapy platform in localized tumor treatment: A review

Due to limitations of treatment and the stubbornness of infiltrative tumor cells, the outcome of conventional antitumor treatment is often compromised by a variety of factors, including severe side effects, unexpected recurrence, and massive tissue loss during the treatment. Hydrogel-based therapy is becoming a promising option of cancer treatment, because of its controllability, biocompatibility, high drug loading, prolonged drug release, and specific stimuli-sensitivity. Hydrogel-based therapy has good malleability and can reach some areas that cannot be easily touched by surgeons. Furthermore, hydrogel can be used not only as a carrier for tumor treatment agents, but also as a scaffold for tissue repair. In this review, we presented the latest researches in hydrogel applications of localized tumor therapy and highlighted the recent progress of hydrogel-based therapy in preventing postoperative tumor recurrence and improving tissue repair, thus proposing a new trend of hydrogel-based technology in localized tumor therapy. And this review aims to provide a novel reference and inspire thoughts for a more accurate and individualized cancer treatment.

Caffeic Acid-coated Nanolayer on Mineral Trioxide Aggregate Potentiates the Host Immune Responses, Angiogenesis, and Odontogenesis

INTRODUCTION

The aim of this study was to investigate whether mineral trioxide aggregate (MTA) can be modified with caffeic acid (CA) to form caffeic acid/mineral trioxide aggregate (CAMTA) cement and to evaluate its physicochemical and biological properties as well as its capability in immune suppression and angiogenesis.

METHODS

MTA was immersed in trishydroxymethyl aminomethane buffer with CA to allow coating onto MTA powders. X-ray diffractometry and tensile stress-strain tests were conducted to assess for physical characteristics of CAMTA and to evaluate for successful modification of MTA. Then, the CAMTA cement was immersed in simulated body fluid to evaluate its hydroxyapatite formation capabilities and Si release profiles. In addition, RAW 264.7 cells and human dental pulp stem cells were used to evaluate CAMTA's immunosuppressive capabilities and cell responses, respectively. hDPSCs were also used to assess CAMTA's angiogenic capabilities.

RESULTS

The X-ray diffractometry results showed that CA can be successfully coated onto MTA without disrupting or losing MTA's original structural properties, thus allowing us to retain the initial advantages of MTA. CAMTA was shown to have higher mechanical properties compared with MTA and had rougher pitted surfaces, which were hypothesized to lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. In addition, it was found that CAMTA was able to enhance hydroxyapatite formation and immunosuppressive capabilities compared with MTA.

CONCLUSIONS

CAMTA cements were found to have improved physicochemical and biological characteristics compared with their counterpart. In addition, CAMTA cements had enhanced odontogenic, angiogenic, and immunosuppressive properties compared with MTA. All of the results of this study proved that CAMTA cements could be a biomaterial for future clinical applications and tissue engineering use.

Mussel-inspired polydopamine-mediated surface modification of freeze-cast poly (ε-caprolactone) scaffolds for bone tissue engineering applications

There are many methods used to fabricate the scaffolds for tissue regeneration, among which freeze casting has attracted a great deal of attention due to the capability to create a unidirectional structure. In this study, polycaprolactone (PCL) scaffolds were fabricated by freeze-casting technology in order to create porous microstructure with oriented open-pore channels. To induce biomineralization, and to improve hydrophilicity and cell interactions, mussel-inspired polydopamine (PDA) was coated on the surface of the freeze-cast PCL constructs. Then, the synergistic effects of oriented microstructure and deposited layer on efficient reconstruction of injured bone were studied. Microscopic observations demonstrated that, the coated layer did not show any special change in lamellar microstructure of the scaffolds. Water-scaffold interactions were evaluated by contact angle measurements, and they demonstrated strong enhancement in the hydrophilicity of the polymeric scaffolds after PDA coating. Biodegradation ratio and water uptake evaluation confirmed an increase in the measured values after PDA precipitation. The biomineralization of the PDA-coated scaffolds was characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). Obtained results confirmed biomineralization of the constructs after a 28-day immersion in a simulated body fluid (SBF) solution. Mechanical analysis demonstrated higher compressive strength after PDA coating. L929 fibroblast cell viability and attachment illustrated that PDA-coated PCL scaffolds are able to support cell adhesion and proliferation. The increased secretion of alkaline phosphatase (ALP) after culturing osteosarcoma cell lines (MG-63) revealed the initial capability of scaffolds to induce bone regeneration. Therefore, the PDA-coated scaffolds introduce a promising approach for bone tissue engineering application.

Dopamine-Mediated Zwitterionic Polyelectrolyte-Coated Polypropylene Hernia Mesh with Synergistic Anti-inflammation Effects

Over 20 million ventral hernia repairs are performed worldwide annually and only a minority (<10%) of cases are not mesh-based. However, even polypropylene (PP), endorsed as the "gold standard" of all prosthetic materials used in this field, is still subject to many complications caused by the foreign body reaction (FBR). Here, we describe the buildup of dopamine-mediated zwitterionic poly(sulfobetaine methacrylate) (PSBMA) coatings to inhibit nonspecific protein adsorption. Based on the universal adhesive ability of polydopamine (PDA), PSBMA has been coated on the PP mesh surface via two strategies: sequential deposition (PSBMA-PDA-PP) and co-deposition (PSBMA@PDA-PP). The presence of PSBMA shows great contribution to obviously decreased hydrophobicity of the PP surface (WCA_co = 36.3° and WCA_seq = 30.7°) as well as improved protein resistance (Reduction_co = 74% and Reduction_seq = 82%). Notably, as the intermedia between PP and PSBMA, PDA can endow the PP mesh with antioxidant activity, further featuring synergistic anti-inflammation therapeutic effect when coupled with PSBMA. With almost equal surface content of PSBMA, PSBMA-PDA-PP exhibited a more superior ability against macrophage adhesion and proliferation and showed more significantly decreased releases of TNF-α and IL-6 (p < 0.05) than those of PSBMA@PDA-PP, fundamentally attributed to its more neutral surface potential and the protection for polyphenols of PDA from oxidation with PSBMA as the outer layer. Furthermore, the coating layers demonstrated good stability and no sacrifice of the pristine mechanical property. The proposed dopamine-mediated PSBMA coatings possess high potential in biomedical implant areas for attenuating the FBR.

An efficient functionalization of dexamethasone-loaded polymeric scaffold with [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent for bone regeneration: Synthesis, characterization, and in vitro evaluation

In this study, dexamethasone-loaded gelatin–starch scaffolds were fabricated by the freeze-drying technique under different cooling temperatures and polymeric compositions. The constructs were modified via [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane coupling agent in order to produce a bioactive network structure for bone tissue engineering applications. Herein, the synergistic effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone was examined on the bioactivity and osteogenic behavior of scaffolds. Based on scanning electron microscopy micrographs, more fine pores were formed at higher freezing temperatures. The prepared microstructure at a rapid freezing rate resulted in diminished mechanical properties and a greater level of swelling and durability compared with a slow freezing rate. According to the acquired results, the mechanical strength decreased, while both absorption capacity and mass loss rate increased as a function of starch addition. Furthermore, the enhancement of hydrophilicity and reduction of mechanical stability enhanced the dexamethasone release levels. In addition, the synthesized constructs confirmed the positive effect of [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane and dexamethasone on biomimetic mineralization of the scaffolds. Supporting the cellular adhesion and proliferation alongside the expression of alkaline phosphatase, especially in the presence of dexamethasone, was the other advantage of synthetic scaffolds as a bone reconstructive substitute. Accordingly, drug-loaded hybrid constructs seem to be promising for further preclinical and clinical investigations in bone tissue engineering.

The effect of oxygen plasma pretreatment on the properties of mussel-inspired polydopamine-decorated polyurethane nanofibers

In this study, polyurethane (PU) scaffolds were fabricated by electrospinning technology and modified through the deposition of polydopamine (PDA) on the activated surface under oxygen plasma treatment. Herein, the effect of the modification process on the homogeneous surface coating and the changes in the physicochemical and biological properties were evaluated. Morphological observations demonstrated decoration of the nanofibrous microstructure with PDA, while the uniformity and homogeneity of the deposited layer increased after plasma oxygen treatment. Hydrophilicity measurements and swelling ratio indicated a remarkable improvement in the interaction of scaffolds with water molecules when the PDA coating is applied on the surface of the treated nanofibers. The biomineralization of the samples was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) images. It was found that PDA has the capability for mineralization, and the amount of deposited hydroxyapatite increased as a function of PDA content. The in vitro evaluation of constructs indicated great improvement in cell-scaffold interactions, biocompatibility, and alkaline phosphatase activity after coating the PDA on the plasma-modified matrix. These results suggest that PDA coating, especially after oxygen plasma treatment, improves the physicochemical and in vitro properties of PU scaffolds for bone tissue engineering application.

A novel bio-inspired conductive, biocompatible, and adhesive terpolymer based on polyaniline, polydopamine, and polylactide as scaffolding biomaterial for tissue engineering application

A novel electrically conductive nanofibrous scaffold based on polyaniline-co-(polydopamine-grafted-poly(d,l-lactide)) [PANI-co-(PDA-g-PLA)] was fabricated using electrospinning technique and its physicochemical as well as biological characteristics toward bone tissue engineering (TE) were investigated extensively. In detail, PANI-co-PDA was synthesized via a one-step chemical oxidization approach. Then, d,l-lactaide monomer was grafted onto PDA segment using a ring opening polymerization (ROP) to afford PANI-co-(PDA-g-PLA) terpolymer. The successful synthesis of PANI-co-(PDA-g-PLA) terpolymer was confirmed using FTIR spectroscopy as well as TGA analysis. Finally, a solution of the synthesized terpolymer was electrospun to fabricate a conductive nanofibrous scaffold. Some physicochemical features such as mechanical, conductivity, electroactivity, hydrophobicity, and morphology as well as biological characteristics including biocompatibility, biodegradability, as well as enhancing the cells adhesion and proliferation were investigated. According to the above-mentioned experimental results, the fabricated electrospun nanofibers can be considered as a potential scaffold for TE application, mainly due to its proper physicochemical and biological properties.

Chondroitin sulfate-polydopamine modified polyethylene terephthalate with extracellular matrix-mimetic immunoregulatory functions for osseointegration

Optimal integration between the polyethylene terephthalate (PET) graft and host bone is a prerequisite to obtain a satisfactory outcome after graft implantation for ligament reconstruction.