Hierarchically Designed Biodegradable Polylactide Particles with Unprecedented Piezocatalytic Activity and Biosafety for Tooth Whitening.

At-home tooth whitening solutions with good efficacy and biosafety are highly desirable to meet the ever-growing demand for aesthetic dentistry. As a promising alternative to the classic peroxide bleaching that may damage tooth enamel and gums, piezocatalysis has been recently proposed to realize non-destructive whitening by toothbrushing with piezoelectrical particles. However, traditional particles either pose potential threats to human health or exhibit low piezoresponse to weak mechanical stimuli in the toothbrushing. Here, biocompatible and biodegradable polylactide particles constructed from interlocking crystalline lamellae have been hierarchically designed as next-generation whitening materials with ultra-high piezocatalytic activity and biosafety. By simultaneously controlling the chain conformation within lamellae and the porosity of such unique lamellae network at the nano- and microscales, the particles possessing unprecedented piezoelectricity have been successfully prepared due to the markedly increased dipole alignment, mechanical deformability, and specific surface area. The piezoelectric output can reach as high as 18.8 V, nearly 50 times higher than that of common solid polylactide particles. Consequently, their piezocatalytic effect can be readily activated by a toothbrush to rapidly clean the teeth stained with black tea and coffee, without causing detectable enamel damage. Furthermore, these particles have no cytotoxicity. This work presents a paradigm for achieving high piezoelectric activity in polylactide, which enables its practical application in tooth whitening.

Effect of Plasticization on Stretching Stability of Poly(Vinyl Alcohol) Films: A Case Study Using Glycerol and Water.

Adding small molecular plasticizers is the most common route to tailor the stretchability of poly(vinyl alcohol) (PVA). However, how the plasticization along with the nature of the plasticizer governs the structural homogeneity during stretching remains an open question to answer. Herein, two representative plasticizers, glycerol (GLY) and water, are chosen to endow the PVA films with ductility. It is found that large strain cavitations cause obvious stress whitening in the PVA/H2 O films; on the contrary, most of the PVA/GLY films maintain transparent undergoing tensile deformation. Through a combination of experimental inspections and molecular dynamic simulation, it is revealed that partial water molecules that behave as free water will aggregate into microdomains, which serve as mechanical defects responsible for yielding voids. Whereas, the GLY plasticizer homogeneously disperses at a molecular level and interacts with PVA chains through strong hydrogen bonds. More interestingly, it is illustrated that the dispersion and bound states of plasticizers are closely related to the mechanical character of the plasticized PVA films. These findings offer new insight into the working mechanism of plasticization on the structural stability during stretching, and guide the design of PVA/plasticizer system to obtain excellent comprehensive mechanics.

Protein-Inspired Polymers with Metal-Site-Regulated Ordered Conformations.

Metal ions play critical roles in facilitating peptide folding and inducing conformational transitions, thereby impacting on the biological activity of many proteins. However, the effect of metal sites on the hierarchical structures of biopolymers is still poorly understood. Herein, inspired by metalloproteins, we report an order-to-order conformational regulation in synthetic polymers mediated by a variety of metal ions. The copolymers are decorated with clinically available desferrioxamine (DFO) as an exogenous ligand template, which presents a geometric constraint toward peptide backbone via short-range hydrogen bonding interactions, thus dramatically altering the secondary conformations and self-assembly behaviors of polypeptides and allowing for a controllable ß-sheet to α-helix transition modulated by metal-ligand interactions. These metallopolymers could form ferritin-inspired hierarchical structures with high stability and membrane activity for efficient brain delivery across the blood-brain barrier (BBB) and long-lasting magnetic resonance imaging (MRI) in vivo.

Amphiphilic Core Cross-Linked Star Polymers for the Delivery of Hydrophilic Drugs from Hydrophobic Matrices.

The delivery of hydrophilic drugs from hydrophobic polymers is a long-standing challenge in the biomaterials field due to the limited solubility of the therapeutic agent within the polymer matrix. In this work, we develop a drug delivery mechanism that enables the impregnation and subsequent elution of hydrophilic drugs from a hydrophobic polymer material. This was achieved by synthesizing core cross-linked star polymer amphiphiles with hydrophilic cores and hydrophobic coronas. While significant work has been done to create nanocarriers for hydrophilic drugs, this work is distinct from previous work in that it designs amphiphilic and core cross-linked particles for controlled release from hydrophobic matrices. Ultraviolet-mediated atom transfer radical polymerization was used to synthesize the poly(ethylene glycol) (PEG)-based hydrophilic cores of the star polymers, and hydrophobic coronas of poly(caprolactone) (PCL) were then built onto the stars using ring-opening polymerization. We illustrated the cytocompatibility of PCL loaded with these star polymers through human endothelial cell adhesion and proliferation for up to 7 days, with star loadings of up to 40 wt %. We demonstrated successful loading of the hydrophilic drug heparin into the star polymer core, achieving a loading efficiency and content of 50 and 5%, respectively. Finally, the heparin-loaded star polymers were incorporated into a PCL matrix and sustained release of heparin was illustrated for over 40 days. These results support the use of core cross-linked star polymer amphiphiles for the delivery of hydrophilic drugs from hydrophobic polymer matrices. These materials were developed for application as drug-eluting and biodegradable coronary artery stents, but this flexible drug delivery platform could have impact in a broad range of medical applications.

Chemokine C-C motif ligand 33 is a key regulator of teleost fish barbel development.

Barbels are important sensory organs in teleosts, reptiles, and amphibians. The majority of ∼4,000 catfish species, such as the channel catfish (Ictalurus punctatus), possess abundant whisker-like barbels. However, barbel-less catfish, such as the bottlenose catfish (Ageneiosus marmoratus), do exist. Barbeled catfish and barbel-less catfish are ideal natural models for determination of the genomic basis for barbel development. In this work, we generated and annotated the genome sequences of the bottlenose catfish, conducted comparative and subtractive analyses using genome and transcriptome datasets, and identified differentially expressed genes during barbel regeneration. Here, we report that chemokine C-C motif ligand 33 (ccl33), as a key regulator of barbel development and regeneration. It is present in barbeled fish but absent in barbel-less fish. The ccl33 genes are differentially expressed during barbel regeneration in a timing concordant with the timing of barbel regeneration. Knockout of ccl33 genes in the zebrafish (Danio rerio) resulted in various phenotypes, including complete loss of barbels, reduced barbel sizes, and curly barbels, suggesting that ccl33 is a key regulator of barbel development. Expression analysis indicated that paralogs of the ccl33 gene have both shared and specific expression patterns, most notably expressed highly in various parts of the head, such as the eye, brain, and mouth areas, supporting its role for barbel development.

Enhanced Hydrolytic Resistance of Fluorinated Silicon-Containing Polyether Urethanes.

The hydrolysis of a newly synthesized polyether urethane (PEU) that uses polydimethylsiloxane (PDMS) as a second macrodiol and fluorinated diol (FDO) as another chain extender has been studied via immersion in buffer solutions at 70 °C. The hydrolysis process was monitored using scanning electron microscopy (SEM), gel permeation chromatography (GPC), and tensile testing. After aging for 32 weeks, no surface defect was observed on the fluorinated silicon-containing PEUs (FSPEU). Meanwhile, the addition of FDO did not alter the other issues of bulk hydrolysis, such as the changes in molecular weight and mechanical strength. Moreover, microphase separation of FSPEU was suppressed during temperature-accelerated hydrolysis, whereas aging induced a more noticeable phase of morphological change in silicon-modified PEUs (SPEU) due to the hindrance effect of the fluorinated side chains. The formation of hydrolysis-prone allophanate is also reduced in the presence of FDO. FSPEU with enhanced antihydrolysis performance can potentially be applied to biostable medical devices.

Topical Review: Causes of Refractive Error After Silicone-oil Removal Combined with Cataract Surgery.

SIGNIFICANCE: This review summarizes the main factors of refractive error after silicone oil removal combined with cataract surgery.The post-operative refractive results of silicone oil removal combined with cataract surgery are closely related to the patient's future vision quality. This report summarizes the factors that influence the difference between the actual post-operative refractive power and the pre-operatively predicted refractive power after silicone oil removal combined with cataract surgery, including axial length, anterior chamber depth, silicone oil, commonly used tools for measuring intraocular lens power, and intraocular lens power calculation formulas, among others. The aim of the report is to assist clinical and scientific research on the elimination of refractive error after silicone oil removal combined with cataract surgery.

[Development and prospect of tissue engineering in urology].

Tissue engineering technology and stem cell research based on tissue engineering have made great progresses in overcoming the problems of tissue and organ damage, functional loss and surgical complications. Traditional method is to use biological substitute materials to repair tissues, while tissue engineering technology focuses on combining seed cells with biological materials to form biological tissues with the same structure and function as its own to repair tissue defects. The advantage is that such tissue engineering organs and tissues can solve the problem that the donor material is limited, and effectively reduce complications. The purpose of tissue engineering is to find suitable seed cells and biomaterials which can replace the biological function of original tissue and build suitable microenvironment in vivo. This paper mainly describes current technologies of tissue engineering in various fields of urology, and discusses the future trend of tissue engineering technology in the treatment of complex urinary diseases. The results of this study show that although there are relatively few clinical trials, the good results of the existing studies on animal models reveal a bright future of tissue engineering technology for the treatment of various urinary diseases.

Facile one-step targeted immobilization of an enzyme based on silane emulsion self-assembled molecularly imprinted polymers for visual sensors.

Immobilized enzymes play significant roles in many practical applications. However, the enzymes need to be purified before immobilization by conventional immobilizing methods, and the purification process is expensive, laborious, complicated and results in a decrease of the enzymatic activity. So, we present a novel method by a facile one-step targeted immobilization of an enzyme without a purification process from complex samples. For this purpose, a novel molecularly imprinted polymer was prepared via a silane emulsion self-assembly method using boric acid-modified Fe3O4 nanoparticles as magnetic nuclei, horseradish peroxidase as a template, 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinking agent. The molecularly imprinted polymers were characterized using a scanning electron microscope, X-ray photoelectron spectroscope, vibrating sample magnetometer and X-ray diffractometer. The as-prepared and characterized materials were employed to immobilize horseradish peroxidase from a crude extract of horseradish. Moreover, the immobilized horseradish peroxidase was employed to develop visual sensors for the detection of glucose and sarcosine. This study demonstrated that the molecularly imprinted polymers prepared via the silane emulsion self-assembly method can facilely immobilize horseradish peroxidase from a crude extract of horseradish without any purification process. The developed visual method based on the immobilized horseradish peroxidase shows great potential applications for the visual detection of glucose and sarcosine.

Fenton-Chemistry-Mediated Radical Polymerization.

In this review, the power of a classical chemical reaction, the Fenton reaction for initiating radical polymerizations, is demonstrated. The reaction between the Fenton reagents (i.e., Fe2+ and H2 O2 ) generates highly reactive hydroxyl radicals, which can act as radical initiators for the polymerization of vinyl monomers. Since the Fenton reaction is fast, easy to set up, cheap, and biocompatible, this unique chemistry is widely employed in various polymer synthesis studies via free radical polymerization or reversible addition-fragmentation chain transfer polymerization, and is utilized in a wide range of applications, such as the fabrication of biomaterials, hydrogels, and core-shell particles. Biologically activated Fenton-mediated radical polymerization, which can be performed in aerobic environments, are particularly useful for applications in biomedical systems.

Molecularly imprinted polymer solid-phase microextraction coupled with ultra high performance liquid chromatography and tandem mass spectrometry for rapid analysis of pyrrolizidine alkaloids in herbal medicine.

Pyrrolizidine alkaloids are the most widely distributed natural toxins, and pyrrolizidine alkaloid-containing herbal medicines are probably the most common poisonous plants affecting humans. We reported pyrrolizidine alkaloid-molecularly imprinted polymer solid-phase microextraction for the selective adsorption of toxic pyrrolizidine alkaloids from herbal medicine. A sulfonic compound, sodium allylsulfonate, was chosen as the functional monomer to interact with pyrrolizidine alkaloids through strong ionic interaction. To avoid template leakage and for the aim of cost saving, a relatively cheap dummy template was used for the fabrication of molecularly imprinted polymer-solid-phase microextraction fibers. The obtained fibers showed selective adsorption ability for four pyrrolizidine alkaloids, including europine, echimidine, lasiocarpine, and heliotrine. The extraction parameters, such as extraction time, extraction temperature, shaking speed, elution solvent and elution time, were optimized. Then ultra high performance liquid chromatography with mass spectrometry coupled with molecularly imprinted polymer-solid-phase microextraction method was developed for the fast and efficient analysis of four pyrrolizidine alkaloids from the model herbal plant Farfarae Flos. The established method was validated and exhibited satisfactory accuracy and precision. The present method provides an innovative and fast analytical strategy for the determination of trace toxic pyrrolizidine alkaloids in complicated samples.

The influence of sertraline on depressive disorder after traumatic brain injury: A meta-analysis of randomized controlled studies.

BACKGROUND: Sertraline showed some potential in alleviating depressive disorder after traumatic brain injury. This systematic review and meta-analysis was conducted to investigate the efficacy of sertraline on the treatment of depressive disorder after traumatic brain injury. METHODS: The databases including PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases were systematically searched for collecting the randomized controlled trials (RCTs) regarding the efficacy of sertraline for traumatic brain injury. RESULTS: This meta-analysis included five RCTs. The initial use of sertraline was within 8 weeks after traumatic brain injury. Compared with control group for traumatic brain injury, sertraline treatment showed no significant improvement on Hamilton Depression Rating Scale (HAM-D) (standard mean difference (Std. MD) = -0.08; 95% confidence interval (CI) = -0.45 to 0.28; P = 0.65), anxiety score (Std. MD = 0.08; 95% CI = -0.32 to 0.48; P = 0.69), aggression score (Std. MD = -0.12; 95% CI = -0.56 to 0.32; P = 0.59), or quality of life (QOL) score (Std. MD = -0.06; 95% CI = -0.49 to 0.37; P = 0.78). There was no statistical difference of diarrhea (risk ratio (RR) = 0.85; 95% CI = 0.92 to 3.71; P = 0.08), dizziness (RR = 1.15; 95% CI = 0.57 to 2.31; P = 0.70), dry mouth (RR = 2.44; 95% CI = 0.43 to 13.89; P = 0.32), nausea or vomiting (RR = 1.17; 95% CI = 0.37 to 3.70; P = 0.79) between sertraline group and control group. CONCLUSIONS: Sertraline showed no obvious benefits for the relief of depressive disorder after traumatic brain injury.

Trophic transfer of cyclic methyl siloxanes in the marine food web in the Bohai Sea, China.

Trophic transfer of cyclic methyl siloxanes (CMS) in aquatic ecosystems is an important criterion for assessing its environmental risks. This study researched the trophic transfer of four CMS (octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7)) in marine food web from zooplankton up to seabirds in the Chinese Bohai Sea. In the zooplankton-invertebrate-fish-seabird based food web, the significant trophic magnifications were found for D4 to D6 (D4: R2 = 0.040, p < 0.05, D5: R2 = 0.26, p < 0.0001, D6: R2 = 0.071, p < 0.001), and the significant trophic dilution was found for D7 (R2 = 0.026 and p < 0.05). The trophic magnification factors (TMF) for D4 to D7 were 1.7 (95% confidence interval: 1.1-2.6), 3.5 (2.5-5.0), 1.8 (1.3-2.6), and 0.63 (95% CI: 0.40-0.99) respectively. In the zooplankton-invertebrate-fish based food web, both significant trophic magnification for D5 (R2 = 0.16, p < 0.0001, TMF = 3.0) and significant trophic dilution for D7 (R2 = 0.073, p < 0.01, TMF = 0.4) were found, but for D4 and D6, the trophic magnifications were not significant (D4: R2 = 0.010, p = 0.23, D6: R2 = 0.010, p = 0.23). The trophic transfer of the legacy contaminant BDE-47 and BDE-99 were also conducted as the benchmark chemicals and significant positive correlation was found. As far as we know, this is the first research on the trophic transfer of CMS in the zooplankton-invertebrate-fish-bird food chain which provided new insight of these compounds in the area.

Super Strong All-Cellulose Composite Filaments by Combination of Inducing Nanofiber Formation and Adding Nanofibrillated Cellulose.

In this work, super strong all-cellulose multifilaments were obtained from cellulose dissolved in LiOH/urea system by inducing nanofiber formation, and were simultaneously reinforced by the introduction of TEMPO-oxidized nanofibrillated cellulose (NFC) with mean diameter of 20 nm. The all-cellulose composite filaments (CF) containing only 3 wt % NFC exhibits a high orientation that Herman's parameter is 0.89. Importantly, the NFC can simultaneously reinforce and toughen the CF, with a tensile strength and elongation at break of 3.92 cN/dT and 14.6%, respectively, which make the obtained CF to become super strong. The strengthened mechanism of CF is considered as the nanofibril-induced crystallization and orientation, which makes up for the deficits and constructs a flawless structure in the regenerated cellulose filaments. Of note, the stability of spinning dope was also effectively improved by adding small amount of NFC, which is very important for fiber spinning on industry. This finding contributes to the preparation of high performance regenerated cellulose multifilaments by a simple, energy-efficient, and eco-friendly route.

Simultaneous Improvement of Oxidative and Hydrolytic Resistance of Polycarbonate Urethanes Based on Polydimethylsiloxane/Poly(hexamethylene carbonate) Mixed Macrodiols.

The degradation behaviors including oxidation and hydrolysis of silicone modified polycarbonate urethanes were thoroughly investigated. These polyurethanes were based on polyhexamethylene carbonate (PHMC)/polydimethylsiloxane (PDMS) mixed macrodiols with molar ratio of PDMS ranging from 5% to 30%. It was proved that PDMS tended to migrate toward surface and even a small amount of PDMS could form a silicone-like surface. Macrophages-mediated oxidation process indicated that the PDMS surface layer was desirable to protect the fragile soft PHMC from the attack of degradative species. Hydrolysis process was probed in detail after immersing in boiling buffered water using combined analytical tools. Hydrolytically stable PDMS could act as protective shields for the bulk to hinder the chain scission of polycarbonate carbonyls whereas the hydrolysis of urethane linkages was less affected. Although the promoted phase separation at higher PDMS fractions lead to possible physical defects and mechanical compromise after degradation, simultaneously enhanced oxidation and hydrolysis resistance could be achieved for the polyurethanes with proper PDMS incorporation.

Star Polymers.

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

The fabrication of 3D surface scaffold of collagen/poly (L-lactide-co-caprolactone) with dynamic liquid system and its application in urinary incontinence treatment as a tissue engineered sub-urethral sling: In vitro and in vivo study.

AIMS: To fabricate a novel nanoyarn biomaterial via a dynamic liquid electrospinning system, and to simultaneously evaluate whether nanoyarn is capable of being applied as a urinary sling for future clinical transfer. METHODS: Nanoyarn was cultured with adipose-derived stem cells (ADSCs). Cell morphology and function were observed on nanoyarn. Female rats that underwent vagina dilatation (VD) and bilateral ovarian resection (BOR) were used as the urinary incontinence model. After 2 weeks, the cells-sling was fixed to the suburethra. A commercial sling that tension-free vaginal tape-obturator (TVT-O) was used as a control. The urodynamic test for leak point pressure (LPP) and histological tests were used to evaluate the sling's performance in vivo. RESULTS: The nanoyarn possessed beneficial properties and the actin filament from ADSCs, which is very similar to muscle. Rats that underwent VD and BOR maintained a low LPP, whereas the LPP in rats with VD alone recovered to normal levels within 2 weeks. LPP in the nanoyarn group gradually decreased on the three urodynamic tests post-suburethral surgery, however, the cell-laden nanoyarn maintained LPP at normal levels for 8 weeks; the TVT-O group showed a significant increase in LPP at 8 weeks. Cell-laden nanoyarn was infiltrated with more cells, collagen, and vessels than the controls. CONCLUSIONS: The nanoyarn showed sufficient efficacy to maintain LPP in urinary incontinence rat model. In addition, it improved cell infiltration, collagen and muscle development compared to TVT-O. Thus, the combination of ADSCs and a nanoyarn scaffold could be a promising tissue-engineered sling for the treatment of urinary incontinence.

Facile preparation of magnetic molecularly imprinted polymers for the selective extraction and determination of dexamethasone in skincare cosmetics using HPLC.

Dexamethasone-imprinted polymers were fabricated by reversible addition-fragmentation chain transfer polymerization on the surface of magnetic nanoparticles under mild polymerization conditions, which exhibited a narrow polydispersity and high selectivity for dexamethasone extraction. The dexamethasone-imprinted polymers were characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive spectrometry, and vibrating sample magnetometry. The adsorption performance was evaluated by static adsorption, kinetic adsorption and selectivity tests. The results confirmed the successful construction of an imprinted polymer layer on the surface of the magnetic nanoparticles, which benefits the characteristics of high adsorption capacity, fast mass transfer, specific molecular recognition, and simple magnetic separation. Combined with high-performance liquid chromatography, molecularly imprinted polymers as magnetic extraction sorbents were used for the rapid and selective extraction and determination of dexamethasone in skincare cosmetic samples, with the accuracies of the spiked samples ranging from 93.8 to 97.6%. The relative standard deviations were less than 2.7%. The limit of detection and limit of quantification were 0.05 and 0.20 µg/mL, respectively. The developed method was simple, fast and highly selective and could be a promising method for dexamethasone monitoring in cosmetic products.

Facile preparation of polydopamine-coated imprinted polymers on the surface of SiO2 for estrone capture in milk samples.

Estrone molecularly imprinted polymers were synthesized through the self-polymerization of dopamine on the surface of silica gels, which had the characteristics of mild polymerization conditions, simple reaction procedure and good specific recognition ability for estrone. The estrone molecularly imprinted polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis and nitrogen adsorption-desorption tests. The characterization confirmed that the imprinted polymers were successfully grafted on the surface of silica gels. Through investigating the adsorption performance, the prepared estrone molecularly imprinted polymers exhibited high adsorption capacity, fast mass transfer, as well as excellent selectivity toward estrone. The estrone molecularly imprinted polymers as the solid-phase extraction adsorbent coupled with high-performance liquid chromatography was developed to determine estrone from the milk samples. The developed estrone molecularly imprinted polymer solid-phase extraction with high-performance liquid chromatography method exhibited satisfactory specificity, precision, accuracy and good linearity relationship in the range of 0.2-20 µg/mL. The developed method is simple, fast, effective and high specificity method and it provides a new method to detect the residues of estrone in animal foods.