Tailored Functional Surfaces Using Nanoparticle and Protein "Nanobrick" Coatings

Surface properties are an essential feature in a wide range of functional materials. In this article, we summarize strategies developed in our group that employ nanoparticles and proteins as nanobricks to create thin-film coatings on surfaces. These coatings contain tailorable surface functionality based on the properties of the predesigned nanobricks, parlaying both the chemical and structural features of the precursor particles and proteins. This strategy is versatile, providing the rapid generation of both uniform and patterned coatings that provide "plug-and-play" customizable surfaces for materials and biomedical applications.

Enabling biodegradable functional biomaterials for the management of neurological disorders

An increasing number of patients are being diagnosed with neurological diseases, but are rarely cured because of the lack of curative therapeutic approaches. This situation creates an urgent clinical need to develop effective diagnosis and treatment strategies for repair and regeneration of injured or diseased neural tissues. In this regard, biodegradable functional biomaterials provide promising solutions to meet this demand owing to their unique responsiveness to external stimulation fields, which enable neuro-imaging, neuro-sensing, specific targeting, hyperthermia treatment, controlled drug delivery, and nerve regeneration. This review discusses recent progress in the research and development of biodegradable functional biomaterials including electroactive biomaterials, magnetic materials and photoactive biomaterials for the management of neurological disorders with emphasis on their applications in bioimaging (photoacoustic imaging, MRI and fluorescence imaging), biosensing (electrochemical sensing, magnetic sensing and opical sensing), and therapy strategies (drug delivery, hyperthermia treatment, and tissue engineering). It is expected that this review will provide an insightful discussion on the roles of biodegradable functional biomaterials in the diagnosis and treatment of neurological diseases, and lead to innovations for the design and development of the next generation biodegradable functional biomaterials.

Preparation and Performance of Antibacterial Polyvinyl Alcohol/Polyethylene Glycol/Chitosan Hydrogels Containing Silver Chloride Nanoparticles via One-step Method

Silver nano-particles (AgNPs)-filled antibacterial materials have been widely employed in the fields of biology and biomedicine. However, AgNPs have shown obvious cytotoxicity. Hence it is more reasonable to use silver chloride nanoparticles (AgCl NPs) to prepare antibacterial materials due to the slow release of silver ions created by AgCl NPs formed in the chitosan. In this experiment, a useful antibacterial hydrogel for skin repairation was prepared by exploring the relationship between AgCl NPs and cytotoxicity. It is worth noting that the crosslinked network structure was successfully obtained in an antibacterial AgCl/PVA (Polyvinyl alcohol)/PEG (Polyethylene glycol)/CS (Chitosan) hydrogel materials by the hydrothermal method. In detail, the dynamic particle size distribution of AgCl NPs was relatively uniform, which is analyzed by a dynamic light scattering (DLS). The internal structure of the lyophilized hydrogel showed obvious porous structure, indicating that the hydrogel had high water content. The result of X-ray photoelectron spectroscopy (XPS) confirmed the existence of a silver element. The release concentration of silver ions was analyzed by inductively coupled plasma (ICP) to study the effect of silver ions release concentration on the antibacterial activity and cytotoxicity of hydrogel. The results show that the lower concentration of silver ions can make the hydrogel have good antibacterial activity and low cytotoxicity. The bacteriostatic rate of the antibacterial hydrogel was over 90%. Simultaneously, the mechanical properties test shows that the hydrogel has good mechanical properties, which can be widely used as an antibacterial material.

Thermal Stability and Flame Retardancy Properties of Epoxy Resin Modified with Functionalized Graphene Oxide Containing Phosphorus and Silicon Elements

Phosphorus- and silicon-modified graphene oxide was prepared to improve the thermal stability and flame retardancy properties of epoxy resin. 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and vinyltriethoxysilane (VTES) were successfully grafted onto the surface of graphene oxide (GO) through solvothermal synthesis and hydrolysis-condensation reaction, respectively. Subsequently, the functionalized graphene oxide grafted by DOPO and VTES (DOPO-VTES-GO) was incorporated into the epoxy resin by the solution blending method. The effect of DOPO-VTES-GO on the thermal stability and flame-retardant properties of epoxy resin was systematically studied. Thermogravimetric analysis showed that the thermal stability and char residue yield of DOPO-VTES-GO/epoxy were increased obviously compared with those of pure epoxy resin and DOPO-GO/epoxy. Cone calorimeter test results showed that DOPO-VTES-GO/epoxy had better flame retardancy than pure epoxy resin and DOPO-GO/epoxy on reducing the peak of heat release rate, total heat release, and total smoke production. Furthermore, the char residue after the cone calorimeter tests was investigated by scanning electron microscopy-energy-dispersive X-ray spectrometry, Raman spectroscopy, and Fourier transform infrared measurements. These results demonstrated that the DOPO-VTES-GO can enhance the graphitization degree of char residues and promote the formation of the thermally stable char. In addition, the mechanism of flame retardancy was proposed, and DOPO-VTES-GO exerts the synergistic effect mainly by means of catalytic charring in the condensed phase and capturing hydroxyl or hydrogen radicals from thermal decomposition of epoxy resin in the gas phase. This work provides novel insights into the preparation of phosphorus-silicon-graphene oxide ternary synergistic flame retardants for thermosetting polymer materials.

Highly transparent, highly flexible composite membrane with multiple antimicrobial effects used for promoting wound healing

In recent years, bacterial cellulose (BC)-based dressings or patches for skin or soft tissue repair have become investigative emphasis. However, most of the BC-based products used for biomedical applications present limitations due to their low flexibility, poor gas permeability and no inherent antibacterial activity. Herein, we proposed and designed a novel composite composed of natural bacterial cellulose (BC), polyethylene glycol (PEG) and polyhexamethylene biguanidine (PHMB) through new synthetic approaches. The composite membrane exhibited favorable physicochemical performance, especially transparency, water retention ability, flexibility as well as the characteristic of anti-adhesion. In vitro biochemical experiment results indicated that the composite had excellent biocompatibility and exhibited strong and sustained antibacterial effect. In vivo test further demonstrated that the composite could efficiently promote skin wound healing and regeneration in a rat model. This composite membrane possesses multiple mechanisms of promoting cutaneous wound healing and will provide new ideas for future development of wound dressings.

The role of macrophages in the resolution of inflammation

Macrophages are tissue-resident or infiltrated immune cells critical for innate immunity, normal tissue development, homeostasis, and repair of damaged tissue. Macrophage function is a sum of their ontogeny, the local environment in which they reside, and the type of injuries or pathogen to which they are exposed. In this Review, we discuss the role of macrophages in the restoration of tissue function after injury, highlighting important questions about how they respond to and modify the local microenvironment to restore homeostasis.

Сhiral and Racemic Fields Concept for Understanding of the Homochirality Origin, Asymmetric Catalysis, Chiral Superstructure Formation from Achiral Molecules, and B-Z DNA Conformational Transition

The four most important and well-studied phenomena of mirror symmetry breaking of molecules were analyzed for the first time in terms of available common features and regularities. Mirror symmetry breaking of the primary origin of biological homochirality requires the involvement of an external chiral inductor (environmental chirality). All reviewed mirror symmetry breaking phenomena were considered from that standpoint. A concept of chiral and racemic fields was highly helpful in this analysis. A chiral gravitational field in combination with a static magnetic field (Earth’s environmental conditions) may be regarded as a hypothetical long-term chiral inductor. Experimental evidences suggest a possible effect of the environmental chiral inductor as a chiral trigger on the mirror symmetry breaking effect. Also, this effect explains a conformational transition of the right-handed double DNA helix to the left-handed double DNA helix (B-Z DNA transition) as possible DNA damage.

Does anchorage loss differ with 0.018-inch and 0.022-inch slot bracket systems?

OBJECTIVES

To compare maxillary first molar anchorage loss between 0.018-inch and 0.022-inch slot fixed appliance systems.

MATERIALS AND METHODS

Patients requiring bilateral maxillary premolar extractions (n = 74) within a randomized clinical trial comparing the effectiveness of 0.018-inch and 0.022-inch slot MBT bracket systems (3M-Unitek, Monrovia, Calif) were included. Three-dimensional pre- and posttreatment digital models were landmarked and measured (R700 scanner and OrthoAnalyzer software, 3Shape, Copenhagen, Denmark). Anteroposterior position of the first molars was measured using the third medial rugae point as a reference. Anchorage loss (AL) represented the subtraction of the posttreatment distance from the pretreatment distance for both anchorage loss right (ALR) and left (ALL) sides. The values were then compared using a two-way analysis of variance.

RESULTS

There were 41 and 33 cases for the 0.018-inch and 0.022-inch bracket slot systems, respectively. The baseline characteristics were similar between groups, except for the presence or absence of anchorage devices (P = .050). For the total sample: 0.018-inch ALR = 3.86 mm, ALL = 3.30 mm and 0.022-inch ALR = 3.73 mm, ALL = 3.47 mm (P = .970). There was also no significant difference between the 0.018-inch and 0.022-inch groups when subjects with anchorage devices were excluded (P = .383).

CONCLUSIONS

Bracket slot size does not influence maxillary molar anchorage loss during orthodontic treatment.

Design and evaluation of chitosan/chondroitin sulfate/nano-bioglass based composite scaffold for bone tissue engineering

Chitosan, a natural biopolymer with osteoconductive properties is widely investigated to generate scaffolds for bone tissue engineering applications. However, chitosan based scaffolds lacks in mechanical strength and structural stability in hydrated condition and thereby limits its application for bone tissue regeneration. Thus in the present study, to overcome the limitations associated with chitosan based scaffolds, we fabricated polyelectrolyte complexation mediated composite scaffold of chitosan and chondroitin sulfate incorporated with nano-sized bioglass. Developed scaffolds were successfully characterized for various morphological, physico-chemical, mechanical and apatite forming properties using XRD, FT-IR, FE-SEM and TEM. It was observed that polyelectrolyte complexation followed by incorporation of bioglass significantly enhances mechanical strength, reduces excessive swelling behavior and enhances structural stability of the scaffold in hydrated condition. Also, in-vitro cell adhesion, spreading, viability and cytotoxity were investigated to evaluate the cell supportive properties of the developed scaffolds. Furthermore, alkaline phosphatase activity, biomineralization and collagen type I expression were observed to be significantly higher over the composite scaffold indicating its superior osteogenic potential. More importantly, in-vivo iliac crest bone defect study revealed that implanted composite scaffold facilitate tissue regeneration and integration with native bone tissue. Thus, developed composite scaffold might be a suitable biomaterial for bone tissue engineering applications.

Recent Advances in Anti-virulence Therapeutic Strategies With a Focus on Dismantling Bacterial Membrane Microdomains, Toxin Neutralization, Quorum-Sensing Interference and Biofilm Inhibition

Antimicrobial resistance constitutes one of the major challenges facing humanity in the Twenty-First century. The spread of resistant pathogens has been such that the possibility of returning to a pre-antibiotic era is real. In this scenario, innovative therapeutic strategies must be employed to restrict resistance. Among the innovative proposed strategies, anti-virulence therapy has been envisioned as a promising alternative for effective control of the emergence and spread of resistant pathogens. This review presents some of the anti-virulence strategies that are currently being developed, it will cover strategies focused on quench pathogen quorum sensing (QS) systems, disassemble of bacterial functional membrane microdomains (FMMs), disruption of biofilm formation and bacterial toxin neutralization.

A High-Lignin-Content, Removable, and Glycol-Assisted Repairable Coating Based on Dynamic Covalent Bonds

Conventional thermoset coatings cannot be easily repaired and removed owing to their highly crosslinked structure. The investigation of repairable or removable coatings has been receiving extensive attention, but few reported coatings possess both features. In this work, a repairable and removable coating was developed through the curing of a modified Kraft lignin (L-COOH) with poly(ethylene glycol) diglycidyl ether (PEG-epoxy) in the presence of zinc catalyst. The L-COOH was prepared by functionalization of Kraft lignin with carboxylic acid groups. The cured material had a high lignin content (>47 wt %). At elevated temperatures (>140 °C), dynamic transesterification in the cured network was activated, which resulted in fast stress relaxation and imparted excellent repairability. If the vitrimer system was used as a coating for tin plates, it provided adequate hardness and adhesion properties. In addition, the lignin-PEG coating could be easily removed from the tin plate by using a mild (0.01-0.1 m) NaOH aqueous solution owing to the unique swelling ability of the coating in alkaline aqueous solution. With the assistance of ethylene glycol, this coating could achieve stress-free repairability in 15 min. This work demonstrates the first lignin-based repair- and removable epoxy coating based on vitrimer chemistry.

Photoinduced Surface Zwitterionization for Antifouling of Porous Polymer Substrates

Surface functionalization of polymeric porous substrates is one of the most important requirements to enhance their applications in the biomedical field. In this study, we achieved photoinduced surface modification using a highly efficient reaction of hydrophilic polymers bearing phosphorylcholine groups. Polymers composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) units and 2-( N-ethylanilino)ethyl methacrylate units were synthesized with attention to the polymer architectures. The surface modification of the porous polyethylene (PE) substrates was carried out by the coating of the MPC polymers with a photochemical radical generator, followed by photoirradiation for a few minutes. Surface analysis by attenuated total reflectance Fourier transform IR spectroscopy and X-ray photoelectron spectroscopy indicated that the MPC polymer layer was generated on the PE surface. Cross-sectional confocal microscopy images showed that the MPC polymers were coated on the polymer surface, even inside the porous structure of the PE substrate. After modification, the porous PE substrates showed a significant increase in hydrophilicity and the water-penetration rate through the pores. Furthermore, the amount of protein adsorbed on the PE substrate was reduced significantly by the surface modification. These functionalities were dependent on the MPC polymer architectures. Thus, we concluded that the photoreactive polymer system developed furnished the porous substrates with antifouling properties.

Design and preparation of Fe3O4@PVA polymeric magnetic nanocomposite film and surface coating by sulfonic acid via in situ methods and evaluation of its catalytic performance in the synthesis of dihydropyrimidines

For the first time, the design and preparation of magnetic polyvinyl alcohol (Fe₃O₄@PVA) nanocomposite film as a novel nanocatalyst was accomplished by in situ precipitation method. To enhance the catalysis activity, the surface modification of this nanocomposite was carried out by sulfonic acid. After the synthesis of this nanocomposite film, Fourier-transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) images, X-ray diffraction (XRD) pattern, N₂ adsorption–desorption by Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM) were utilized to confirm the structure of the nanocomposite. The catalytic activity of Fe₃O₄@PVA was investigated by the synthesis of dihydropyrimidine derivatives from an aldehyde, ß-ketoester and urea or thiourea. This heterogeneous nanocatalyst can be easily separated by an external magnet and reused for several times without any significant loss of activity. Simple work-up, mild reaction conditions and easily recoverable catalyst are the advantageous of this nanocomposite film.

Machine learning metrology of cell confinement in melt electrowritten three-dimensional biomaterial substrates

Tuning cell shape by altering the biophysical properties of biomaterial substrates on which cells operate would provide a potential shape-driven pathway to control cell phenotype. However, there is an unexplored dimensional scale window of three-dimensional (3D) substrates with precisely tunable porous microarchitectures and geometrical feature sizes at the cell's operating length scales (10-100 μm). This paper demonstrates the fabrication of such high-fidelity fibrous substrates using a melt electrowriting (MEW) technique. This advanced manufacturing approach is biologically qualified with a metrology framework that models and classifies cell confinement states under various substrate dimensionalities and architectures. Using fibroblasts as a model cell system, the mechanosensing response of adherent cells is investigated as a function of variable substrate dimensionality (2D vs. 3D) and porous microarchitecture (randomly oriented, "non-woven" vs. precision-stacked, "woven"). Single-cell confinement states are modeled using confocal fluorescence microscopy in conjunction with an automated single-cell bioimage data analysis workflow that extracts quantitative metrics of the whole cell and sub-cellular focal adhesion protein features measured. The extracted multidimensional dataset is employed to train a machine learning algorithm to classify cell shape phenotypes. The results show that cells assume distinct confinement states that are enforced by the prescribed substrate dimensionalities and porous microarchitectures with the woven MEW substrates promoting the highest cell shape homogeneity compared to non-woven fibrous substrates. The technology platform established here constitutes a significant step towards the development of integrated additive manufacturing-metrology platforms for a wide range of applications including fundamental mechanobiology studies and 3D bioprinting of tissue constructs to yield specific biological designs qualified at the single-cell level.

Microfluidic Electrospray Niacin Metal-Organic Frameworks Encapsulated Microcapsules for Wound Healing

Niacin metal-organic frameworks (MOFs) encapsulated microcapsules with alginate shells and copper-/zinc-niacin framework cores were in situ synthesized by using a microfluidic electrospray approach for wound healing. As the alginate shells were bacteria-responsively degradable, the niacin MOFs encapsulated microcapsules could intelligently, controllably, and programmably release calcium, copper, and zinc ions, depending on the degree of infections. The released ions could not only kill microbes by destroying their membrane and inducing the outflow of nutrient substance, but also activate copper/zinc superoxide dismutase (Cu/Zn-SOD) to eliminate oxygen free radicals and rescue the cells from oxidative stress injury. Furthermore, the simultaneously released niacin could promote hemangiectasis and absorption of functional metal ions. Thus, the niacin MOFs encapsulated microcapsules were imparted with outstanding antibacterial, antioxidant, and angiogenesis properties. Based on an in vivo study, we have also demonstrated that the chronic wound healing process of an infected full-thickness skin defect model could be significantly enhanced by using the niacin MOFs encapsulated microcapsules as therapeutic agent. Therefore, the microfluidic electrospray niacin MOFs encapsulated microcapsules are potential for clinical applications.

Magnetic Cell-Scaffold Interface Constructed by Superparamagnetic IONP Enhanced Osteogenesis of Adipose-Derived Stem Cells

One of the key factors in tissue engineering and regenerative medicine is to optimize the interaction between seed cells and scaffolds such that the cells can grow in naturally biomimetic conditions. Their similarity to macromolecules and many unique properties mean that functional nanoparticles have promising potential for the modification and improvement of traditional scaffolds to obtain excellent biocompatibility, tunable stiffness, physical sensing, and stimulus-response capabilities. In the present study, we report magnetic poly(lactic- co-glycolic acid)/polycaprolactone (PLGA/PCL) scaffolds that were fabricated using a combination of the electrospinning technique and layer-by-layer assembly of superparamagnetic iron oxide nanoparticles (IONPs). PLGA/PCL scaffolds assembled with gold nanoparticles were prepared using the same method for comparison. The results showed that the assembled film of nanoparticles on the surface greatly enhanced the hydrophilicity and increased the elastic modulus of the scaffold, which subsequently improved the osteogenesis of the stem cells. Furthermore, the magnetic property of the IONPs proved to be the key factor in enhancing osteogenic differentiation, which explained the superior osteogenic capacity of the magnetic scaffolds compared with that of the gold nanoparticle-assembled scaffold. These results demonstrated the importance of magnetic nanomaterials as a bioactive interface between cells and scaffolds and will promote the design of biomaterials to improve tissue engineering and regenerative medicine efficacy.

Bioactive Carbon-Based Hybrid 3D Scaffolds for Osteoblast Growth

Bone, nerve, and heart tissue engineering place high demands on the conductivity of three-dimensional (3D) scaffolds. Fibrous carbon-based scaffolds are excellent material candidates to fulfill these requirements. Here, we show that highly porous (up to 94%) hybrid 3D framework structures with hierarchical architecture, consisting of microfiber composites of self-entangled carbon nanotubes (CNTs) and bioactive nanoparticles are highly suitable for growing cells. The hybrid 3D structures are fabricated by infiltrating a combination of CNTs and bioactive materials into a porous (∼94%) zinc oxide (ZnO) sacrificial template, followed by the removal of the ZnO backbone via a H2 thermal reduction process. Simultaneously, the bioactive nanoparticles are sintered. In this way, conductive and mechanically stable 3D composites of free-standing CNT-based microfibers and bioactive nanoparticles are formed. The adopted strategy demonstrates great potential for implementing low-dimensional bioactive materials, such as hydroxyapatite (HA) and bioactive glass nanoparticles (BGN), into 3D carbon-based microfibrous networks. It is demonstrated that the incorporation of HA nanoparticles and BGN promotes the biomineralization ability and the protein adsorption capacity of the scaffolds significantly, as well as fibroblast and osteoblast adhesion. These results demonstrate that the developed carbon-based bioactive scaffolds are promising materials for bone tissue engineering and related applications.

Albumin conjugates and assemblies as versatile bio-functional additives and carriers for biomedical applications

As the most abundant plasma protein, serum albumin has been extensively studied and employed for therapeutic applications. Despite its direct clinical use for the maintenance of blood homeostasis in various medical conditions, this review exclusively summarizes and discusses albumin-based bio-conjugates and assemblies as versatile bio-functional additives and carriers in biomedical applications. As one of the smallest-sized proteins in the human body, albumin is physiochemically stable and biochemically inert. Moreover, albumin is also endowed with abundant specific binding sites for numerous therapeutic compounds, which also endow it with superior bioactivities. Firstly, due to its small size and binding specificity, albumin alone or its derived assemblies can be utilized as competent drug carriers, which can deliver drugs through the enhanced permeability and retention (EPR) effect or actively target lesion sites through binding with gp60 and secreted protein acidic and rich in cysteine (SPARC) in tumor sites. Furthermore, its biochemical stability and inertness make it a safe and biocompatible coating material for use in biomedical applications. Albumin-based surface modifying additives can be used to functionalize both macro substrates (e.g. surfaces of medical devices or implants) and nanoparticle surfaces (e.g. drug carriers and imaging contrast agents). In this review, we elaborate on the synthesis and applications of albumin-based bio-functional coatings and drug carriers, respectively.

Development of a 3D Collagen Model for the In Vitro Evaluation of Magnetic-assisted Osteogenesis

Magnetic stimulation has been applied to bone regeneration, however, the cellular and molecular mechanisms of repair still require a better understanding. A three-dimensional (3D) collagen model was developed using plastic compression, which produces dense, cellular, mechanically strong native collagen structures. Osteoblast cells (MG-63) and magnetic iron oxide nanoparticles (IONPs) were incorporated into collagen gels to produce a range of cell-laden models. A magnetic bio-reactor to support cell growth under static magnetic fields (SMFs) was designed and fabricated by 3D printing. The influences of SMFs on cell proliferation, differentiation, extracellular matrix production, mineralisation and gene expression were evaluated. Polymerase chain reaction (PCR) further determined the effects of SMFs on the expression of runt-related transcription factor 2 (Runx2), osteonectin (ON), and bone morphogenic proteins 2 and 4 (BMP-2 and BMP-4). Results demonstrate that SMFs, IONPs and the collagen matrix can stimulate the proliferation, alkaline phosphatase production and mineralisation of MG-63 cells, by influencing matrix/cell interactions and encouraging the expression of Runx2, ON, BMP-2 and BMP-4. Therefore, the collagen model developed here not only offers a novel 3D bone model to better understand the effect of magnetic stimulation on osteogenesis, but also paves the way for further applications in tissue engineering and regenerative medicine.

Significantly improved piezoelectric performance of PZT-PMnN ceramics prepared by spark plasma sintering

A high-performance piezoelectric material, 0.95Pb(Zr_0.52Ti_0.48)O₃-0.05Pb(Mn_1/3Nb_2/3)O₃ (PZT-PMnN) ceramic, was prepared by using a spark plasma sintering (SPS) method. By systematically comparing the electrical properties, the spark-plasma-sintered sample was demonstrated to be superior to a conventionally sintered sample. With respect to conventionally sintered ceramic, the d ₃₃ of spark-plasma-sintered ceramic increases from 323 pC/N to 412 pC/N, and the increases from 318 pm V^-1 to 553 pm V^-1. More importantly, the mechanical quality factor (Q _m) reaches 583, which is three times higher than the conventionally sintered sample (Q _m ∼ 182). Furthermore, the SPS method was found to be capable of promoting other electrical properties simultaneously. Therefore, the SPS method is proposed to be an effective processing method to fabricate PZT-PMnN ceramics of higher performance.

Short duration cancer treatment: inspired by a fast bio-resorbable smart nano-fiber device containing NIR lethal polydopamine nanospheres for effective chemo-photothermal cancer therapy

BACKGROUND

The objective of this study was to evaluate the efficacy of a combination of Photothermal therapy (PTT) and chemotherapy in a single nano-fiber platform containing lethal polydopamine nanopheres (PD NPs) for annihilation of CT 26 cancer cells.

METHOD

Polydioxanone (PDO) nanofiber containing PD and bortezomib (BTZ) was fabricated via electrospinning method. The content of BTZ and PD after optimization was 7% and 2.5% respectively with respect to PDO weight. PD NPs have absorption band in near-infrared (NIR) with resultant rapid heating capable of inducing cancer cell death. The samples was divided into three groups - PDO, PDO+PD, and PDO+PD-BTZ for analysis.

RESULTS

In combined treatment, PDO nanofiber alone could not inhibit cancer cell growth as it neither contain PD or BTZ. However, PDO+PD fiber showed a cell viability of approximately 20% after 72 hr of treatment indicating minimal killing via hyperthermia. In the case of PDO composite fiber containing BTZ, the effect of NIR irradiation reduced the viability of cancer cells down to around 5% after 72 h showing the efficiency of combination therapy on cancer cells elimination. However, due to higher photothermal conversion that may negatively affect normal cells above 46°C, we have employed 1 s "OFF" and 2 s "ON" after initial 9 s continuous irradiation to maintain the temperature between 42 and 46°C over 3 mins of treatment using 2 W/cm2; 808 nm laser which resulted to similar cell death.

CONCLUSION

In this study, combination of PTT and chemotherapy treatment on CT 26 colon cancer cells within 3 min resulted in effective cell death in contrast to single treatment of either PTT and chemotherapy alone. Our results suggest that this nanofiber device with efficient heating and remote control drug delivery system can be useful and convenient in the future clinical application for localized cancer therapy.

Suppressing inflammation and enhancing osteogenesis using novel CS-EC@Ca microcapsules

The aim of this study was to investigate the suppression of inflammation and enhancement of osteogenesis using chitosan-coated calcium hydroxide-loaded microcapsules (CS-EC@Ca microcapsules) in vivo. Circular defects were created in the mandibular bones of rabbits and filled with Ca(OH)₂ , Bio-oss, or CS-EC@Ca microcapsules, and rabbits without drug implantation served as the controls. Lipopolysaccharides were injected in situ daily in all groups for 7 days. Mandibular bones were investigated at 4 and 12 weeks after surgery using micro-CT, histological observations, and real-time PCR analysis. At the postoperation, there was more substantial nascent bone in the microcapsule and Bio-oss groups than in the control group. The recovery of the rabbits in the Ca(OH)₂ group was slower than the control group, as determined using micro-CT and histological staining. Osteocalcin and collagen type I production was not significantly different between the microcapsule and Bio-oss groups (p > 0.05), but the expression levels of the two molecules were significantly increased compared to the control and Ca(OH)₂ groups at postoperation (p < 0.05). The mRNA transcript levels of inflammatory factors in the microcapsule group had the most reduced expression of IL-6 and TNF-α (p < 0.05). The microcapsules significantly reduced inflammation and promoted osteogenesis in this rabbit model of inflammatory bone destruction. Our findings indicate that CS-EC@Ca microcapsules hold potential for use in apical periodontitis treatment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3222-3230, 2018.

Magnetic field and nano-scaffolds with stem cells to enhance bone regeneration

Novel strategies utilizing magnetic nanoparticles (MNPs) and magnetic fields are being developed to enhance bone tissue engineering efficacy. This article first reviewed cutting-edge research on the osteogenic enhancements via magnetic fields and MNPs. Then the current developments in magnetic strategies to improve the cells, scaffolds and growth factor deliveries were described. The magnetic-cell strategies included cell labeling, targeting, patterning, and gene modifications. MNPs were incorporated to fabricate magnetic composite scaffolds, as well as to construct delivery systems for growth factors, drugs and gene transfections. The novel methods using magnetic nanoparticles and scaffolds with magnetic fields and stem cells increased the osteogenic differentiation, angiogenesis and bone regeneration by 2-3 folds over those of the controls. The mechanisms of magnetic nanoparticles and scaffolds with magnetic fields and stem cells to enhance bone regeneration were identified as involving the activation of signaling pathways including MAPK, integrin, BMP and NF-κB. Potential clinical applications of magnetic nanoparticles and scaffolds with magnetic fields and stem cells include dental, craniofacial and orthopedic treatments with substantially increased bone repair and regeneration efficacy.

Digital platform for planning facial asymmetry orthodontic-surgical treatment preparation

Dentofacial deformities usually are surgically treated, and 3D virtual planning has been used to favor accurate outcomes. Cases reported in the present article show that orthognathic surgery carried out to correct facial asymmetries does not comprise only one treatment protocol. 3D virtual planning might be used for surgical planning, but it should also be used to diagnose the deformity, thus allowing for an analysis of the best-recommended possibilities for the orthodontic preparation that suits each individual case.

Synthesis and Degradation Mechanism of Self-Cured Hyperbranched Epoxy Resins from Natural Citric Acid

Rapid and highly efficient degradation of cured thermoset epoxy resins is a major challenge to scientists. Here, degradable self-cured hyperbranched epoxy resins (DSHE-n, n = 1, 2, and 3) were synthesized by a reaction between 3-isocyanato-4-methyl-epoxy-methylphenylcarbamate and degradable epoxy-ended hyperbranched polyester (DEHP-n) prepared from maleicanhydride, citric acid, and epichlorohydrin. The chemical structure of DSHE-n was characterized by Fourier transform infrared and 1H NMR spectra. With an increase in DSHE-n molecular weight, the adhesion strength of self-cured DSHE-n films increases distinctly from class 1 to 4, and their pencil hardness remains about class B-2B. The study on the self-cured behavior and mechanism of DSHE-n shows that the carbamate group of the DSHE-n is decomposed into diamine group to react with epoxy group and form a cross-linked structure. The self-cured DSHE-n films were degraded completely in 2 h at 90 °C in the mixed solution of hydrogen peroxide (H2O2) and N,N-dimethylformamide under atmospheric pressure and produced the raw material citric acid, indicating good degradation performance and recyclable property of DSHE-n.

In Vivo Investigation into Effectiveness of Fe₃O₄/PLLA Nanofibers for Bone Tissue Engineering Applications

Fe₃O₄ nanoparticles were loaded into poly-l-lactide (PLLA) with concentrations of 2% and 5%, respectively, using an electrospinning method. In vivo animal experiments were then performed to evaluate the potential of the Fe₃O₄/PLLA nanofibrous material for bone tissue engineering applications. Bony defects with a diameter of 4 mm were prepared in rabbit tibias. Fe₃O₄/PLLA nanofibers were grafted into the drilled defects and histological examination and computed tomography (CT) image detection were performed after an eight-week healing period. The histological results showed that the artificial bony defects grafted with Fe₃O₄/PLLA nanofibers exhibited a visibly higher bone healing activity than those grafted with neat PLLA. In addition, the quantitative results from CT images revealed that the bony defects grafted with 2% and 5% Fe₃O₄/PLLA nanofibers, respectively, showed 1.9- and 2.3-fold increases in bone volume compared to the control blank sample. Overall, the results suggest that the Fe₃O₄/PLLA nanofibers fabricated in this study may serve as a useful biomaterial for future bone tissue engineering applications.

Tetrafunctional epoxy as an all‐purpose modifier for homopolymerized bisphenol A diglycidyl ether

In some applications, homopolymerized epoxies, which offer better biocompatibility and lower water absorption than amine‐ and anhydride‐cured epoxy, are more preferable; however, using homopolymerized epoxy as matrix in composites still remains a challenge. Herein, homopolymerized bisphenol A diglycidyl ether curing systems with simultaneously improved tensile strength, impact strength, and glass transition temperature (Tg) were achieved by addition of small amounts of tetra‐functional epoxies (TFTEs) with different spacer lengths. Effects of spacer length in TFTE on thermal and mechanical properties were investigated. Results indicated that TFTE with the longest spacer length shows the best mechanical performance. In addition, effects of TFTE loading on thermal and mechanical properties were discussed. Compared with neat bisphenol A diglycidyl ether, addition of 5% tetraglycidyl‐1,10‐bis(triphenylmethane) decane leads to simultaneous improvements in tensile strength, impact strength, and Tg. Effects of thermal cycling on the mechanical properties were also reported. Results suggest that the modified homopolymerized epoxy shows good performances and could be used as matrix materials and possibly in some dental applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46431.

Zinc Oxide Coated Tin Oxide Nanofibers for Improved Selective Acetone Sensing

Three-dimensional hierarchical SnO₂/ZnO hetero-nanofibers were fabricated by the electrospinning method followed with a low-temperature water bath treatment. These hierarchical hollow SnO₂ nanofibers were assembled by the SnO₂ nanoparticles through the electrospinning process and then the ZnO nanorods were grown vertically on the surface of SnO₂ nanoparticles, forming the 3D nanostructure. The synthesized hollow SnO₂/ZnO heterojunctions nanofibers were further employed to be a gas-sensing material for detection of volatile organic compound (VOC) species such as acetone vapor, which is proposed as a gas biomarker for diabetes. It shows that the heterojunction nanofibers-based sensor exhibited excellent sensing properties to acetone vapor. The sensor shows a good selectivity to acetone in the interfering gases of ethanol, ammonia, formaldehyde, toluene, and methanol. The enhanced sensing performance may be due to the fact that n-n 3D heterojunctions, existing at the interface between ZnO nanorods and SnO₂ particles in the SnO₂/ZnO nanocomposites, could prompt significant changes in potential barrier height when exposed to acetone vapor, and gas-sensing mechanisms were analyzed and explained by Schottky barrier changes in SnO₂/ZnO 3D hetero-nanofibers.

Reducing Bacterial Infections and Biofilm Formation Using Nanoparticles and Nanostructured Antibacterial Surfaces

With the rapid spreading of resistance among common bacterial pathogens, bacterial infections, especially antibiotic-resistant bacterial infections, have drawn much attention worldwide. In light of this, nanoparticles, including metal and metal oxide nanoparticles, liposomes, polymersomes, and solid lipid nanoparticles, have been increasingly exploited as both efficient antimicrobials themselves or as delivery platforms to enhance the effectiveness of existing antibiotics. In addition to the emergence of widespread antibiotic resistance, of equal concern are implantable device-associated infections, which result from bacterial adhesion and subsequent biofilm formation at the site of implantation. The ineffectiveness of conventional antibiotics against these biofilms often leads to revision surgery, which is both debilitating to the patient and expensive. Toward this end, micro- and nanotopographies, especially those that resemble natural surfaces, and nonfouling chemistries represent a promising combination for long-term antibacterial activity. Collectively, the use of nanoparticles and nanostructured surfaces to combat bacterial growth and infections is a promising solution to the growing problem of antibiotic resistance and biofilm-related device infections.

Clinical, Radiological, and Histological Assessment of Magnetic Nanoparticles as Pulpotomy Medicament in Primary Molars

AIM AND OBJECTIVES

Aim of the study was to evaluate the success of magnetic nanoparticles (MNPs) as pulpotomy medicament by clinical, radiologic, and histological assessment in primary molars.

MATERIALS AND METHODS

The sample included 30 primary molars from 25 children aged between 3 and 9 years requiring pulpotomy treatment. Pulpotomy was carried out with MNPs. The teeth were evaluated after a period of 3, 6, and 12 months clinically and with the aid of radiographs. After 1 year, 10 teeth were extracted for histological evaluation under field emission scanning electron microscope (FE-SEM; ZEISS, Model No. Supra 55vp).

RESULTS

Of the samples, 98% showed clinical success rate with absence of pain, swelling, mobility, and abscess formation. After 3 months, 98% radiological success with absence of periodontal ligament widening, root resorption, and inter-radicular radiolucency was noted. Histological examination carried out under FE-SEM revealed a zone of odontoblastic proliferation at the interface between MNPs and odontoblastic layer of pulp and viable pulpal cells from the canal orifice till apical foramen.

CONCLUSION

Magnetic nanoparticles can be recommended as an effective pulpotomy medicament with hard tissue barrier formation and preservation of vitality of remaining radicular pulp.How to cite this article: Konyala HR, Mareddy AR, Puppala N, Reddy NV, Mallela MK, Susheela KP. Clinical, Radiological, and Histological Assessment of Magnetic Nanoparticles as Pulpotomy Medicament in Primary Molars. Int J Clin Pediatr Dent 2018;11(4):283-287.

Phase pure, high hardness, biocompatible calcium silicates with excellent anti-bacterial and biofilm inhibition efficacies for endodontic and orthopaedic applications

Here we report for the very first time the synthesis of 100% phase pure calcium silicate nanoparticles (CSNPs) of the α-wollastonite phase without using any surfactant or peptizer at the lowest ever reported calcination temperature of 850 °C. Further, the phase purity is confirmed by quantitative phase analysis. The nano-network like microstructure of the CSNPs is characterized by FTIR, Raman, XRD, FESEM, TEM, TGA, DSC etc. techniques to derive the structure property correlations. The performance efficacies of the CSNPs against gram-positive e.g., S. pyogenes and S. aureus (NCIM2127) and gram-negative e.g., E. coli (NCIM2065) bacterial strains are studied. The biocompatibility of the CSNPs is established by using the conventional mouse embryonic osteoblast cell line (MC3T3). In addition, the biofilm inhibition efficacies of two varieties of CSNPs e.g., CSNPs(W) and CSNPs(WC) are investigated. Further, the interconnection between ROS e.g., superoxide (O₂^.-) and hydroxyl radical (^.OH) generation capabilities of CSNPs and their biofilm inhibition efficacies is clearly established for the very first time. Finally, the mechanical responses of the CSNPs at the microstructural length scale are investigated by nanoindentation. The results confirm that the α-wollastonite phases present in CSNPs(W) and CSNPs(WC) possess extraordinarily high nanohardness and Young's moduli values. Therefore, these materials are well suited for orthopaedic and endodontic applications.