Investigation of zinc polycarboxylate cement used in dental treatments in terms of retrospective dosimeter.

Zinc polycarboxylate cement is one of the few dental materials that demonstrate true adhesion to tooth structure. It is suitable for use in living organisms without causing harm. Its strong adhesion to teeth and low level of irritancy are two important parameters for the dental applications. In this study, the dosimetry properties of zinc polycarboxylate cement using thermoluminescence (TL) method were investigated and determined the effectiveness of its use as a good dosimeter. According to the results of this study, the sample shows a good TL properties with three main peaks found around 140°C, 220°C and 330°C. It has a wide linear dose response between 72 Gy and 2.3 kGy and good reusability of the TL peak found at 330°C. Unfortunately, the TL peak intensity values are rapidly faded within a short waiting time interval. Zinc polycarboxylate cement, which is frequently used in dental crowns, can be used as a retrospective dosimeter for measuring the amount of radiation in space studies and nuclear accidents due to its wide linear dose-response curve in the high dose region.

Silver nanopopcorns decorated on flexible membrane for SERS detection of nitrofurazone.

The synthesis of three-dimensional silver nanopopcorns (Ag NPCs) onto a flexible polycarbonate membrane (PCM) for the detection of nitrofurazone (NFZ) on the fish surface by surface-enhanced Raman spectroscopy (SERS) is presented. The proposed flexible Ag-NPCs/PCM SERS substrate exhibits significant Raman signal intensity enhancement with the measured enhancement factor of 2.36 × 106. This is primarily attributed to the hotspots created on Ag NPCs, including numerous nanoscale protrusions and internal crevices distributed across the surface of Ag NPCs. The detection of NFZ by this flexible SERS substrate demonstrates a low limit of detection (LOD) of 3.7 × 10-9 M and uniform and reproducible Raman signal intensities with a relative standard deviation below 8.34%. It also exhibits excellent stability, retaining 70% of its efficacy even after 10 days of storage. Notably, the practical detection of NFZ in tap water, honey water, and fish surfaces achieves LOD values of 1.35 × 10-8 M, 5.76 × 10-7 M, and 3.61 × 10-8 M, respectively,  which highlights its effectiveness across different sample types. The developed Ag-NPCs/PCM SERS substrate presents promising potential for sensitive SERS detection of toxic substances in real-world samples.

Construction of Polycarbonates with Pendant Multifunctional Groups via a One-Step CO2/ Diepoxide Copolymerization Approach.

A "one-step" strategy has been demonstrated for the tunable synthesis of multifunctional aliphatic polycarbonates (APCs) with ethylene oxide (EO), ethylene carbonate (EC), and cyclohexene oxide (CHO) side groups by the copolymerization of 4-vinyl-1-cyclohexene diepoxide with carbon dioxide under an aminotriphenolate iron/PPNBz (PPN = bis(triphenylphosphine)-iminium, Bz = benzoate) binary catalyst. By adjusting the PPNBz-to-iron complex ratio and incorporating auxiliary solvents, the content of functional side groups can be tuned within the ranges of 53-75% for EO, 18-47% for EC, and <1-7% for CHO. The yield and molecular weight distribution of the resulting multifunctional APCs are affected by the viscosity of the polymerization system. The use of tetrahydrofuran as an auxiliary solvent enables the preparation of narrow-distribution polycarbonates at high conversion. This work presents a novel perspective for the preparation of tailorable multifunctional APCs.

Exposure to emissions generated by 3-dimensional printing with polycarbonate: effects on peripheral vascular function, cardiac vascular morphology and expression of markers of oxidative stress in male rat cardiac tissue.

Three-dimensional (3D) printing with polycarbonate (PC) plastic occurs in manufacturing settings, homes, and schools. Emissions generated during printing with PC stock and bisphenol-A (BPA), an endocrine disrupter in PC, may induce adverse health effects. Inhalation of 3D printer emissions, and changes in endocrine function may lead to cardiovascular dysfunction. The goal of this study was to determine whether there were any changes in markers of peripheral or cardiovascular dysfunction in animals exposed to PC-emissions. Male Sprague Dawley rats were exposed to PC-emissions generated by 3D printing for 1, 4, 8, 15 or 30 d. Exposure induced a reduction in the expression of the antioxidant catalase (Cat) and endothelial nitric oxide synthase (eNos). Endothelin and hypoxia-induced factor 1α transcripts increased after 30 d. Alterations in transcription were associated with elevations in immunostaining for estrogen and androgen receptors, nitrotyrosine, and vascular endothelial growth factor in cardiac arteries of PC-emission exposed animals. There was also a reduction eNOS immunostaining in cardiac arteries from rats exposed to PC-emissions. Histological analyses of heart sections revealed that exposure to PC-emissions resulted in vasoconstriction of cardiac arteries and thickening of the vascular smooth muscle wall, suggesting there was a prolonged vasoconstriction. These findings are consistent with studies showing that inhalation 3D-printer emissions affect cardiovascular function. Although BPA levels in animals were relatively low, exposure-induced changes in immunostaining for estrogen and androgen receptors in cardiac arteries suggest that changes in the action of steroid hormones may have contributed to the alterations in morphology and markers of cardiac function.

Polycarbonate Ultracentrifuge Tube Re-use in Proteomic Analyses of Extracellular Vesicles.

Single-use laboratory plastics exacerbate the pollution crisis and contribute to consumable costs. In extracellular vesicle (EV) isolation, polycarbonate ultracentrifuge (UC) tubes are used to endure the associated high centrifugal forces. EV proteomics is an advancing field and validated re-use protocols for these tubes are lacking. Re-using consumables for low-yield protein isolation protocols and downstream proteomics requires reagent compatibility with mass spectroscopy acquisitions, such as the absence of centrifuge tube-derived synthetic polymer contamination, and sufficient removal of residual proteins. This protocol describes and validates a method for cleaning polycarbonate UC tubes for re-use in EV proteomics experiments. The cleaning process involves immediate submersion of UC tubes in H2O to prevent protein drying, washing in 0.1% sodium dodecyl sulfate (SDS) detergent, rinsing in hot tap water, demineralized water, and 70% ethanol. To validate the UC tube re-use protocol for downstream EV proteomics, used tubes were obtained following an experiment isolating EVs from cardiovascular tissue using differential UC and density gradient separation. Tubes were cleaned and the experimental process was repeated without EV samples comparing blank never-used UC tubes to cleaned UC tubes. The pseudo-EV pellets obtained from the isolation procedures were lysed and prepared for liquid chromatography-tandem mass spectrometry using a commercial protein sample preparation kit with modifications for low-abundance protein samples. Following cleaning, the number of identified proteins was reduced by 98% in the pseudo-pellet versus the previous EV isolation sample from the same tube. Comparing a cleaned tube against a blank tube, both samples contained a very small number of proteins (≤20) with 86% similarity. The absence of polymer peaks in the chromatograms of the cleaned tubes was confirmed. Ultimately, the validation of a UC tube cleaning protocol suitable for the enrichment of EVs will reduce the waste produced by EV laboratories and lower the experimental costs.

Pulmonary evaluation of whole-body inhalation exposure of polycarbonate (PC) filament 3D printer emissions in rats.

During fused filament fabrication (FFF) 3D printing with polycarbonate (PC) filament, a release of ultrafine particles (UFPs) and volatile organic compounds (VOCs) occurs. This study aimed to determine PC filament printing emission-induced toxicity in rats via whole-body inhalation exposure. Male Sprague Dawley rats were exposed to a single concentration (0.529 mg/m3, 40 nm mean diameter) of the 3D PC filament emissions in a time-course via whole body inhalation for 1, 4, 8, 15, and 30 days (4 hr/day, 4 days/week), and sacrificed 24 hr after the last exposure. Following exposures, rats were assessed for pulmonary and systemic responses. To determine pulmonary injury, total protein and lactate dehydrogenase (LDH) activity, surfactant proteins A and D, total as well as lavage fluid differential cells in bronchoalveolar lavage fluid (BALF) were examined, as well as histopathological analysis of lung and nasal passages was performed. To determine systemic injury, hematological differentials, and blood biomarkers of muscle, metabolic, renal, and hepatic functions were also measured. Results showed that inhalation exposure induced no marked pulmonary or systemic toxicity in rats. In conclusion, inhalation exposure of rats to a low concentration of PC filament emissions produced no significant pulmonary or systemic toxicity.

Antimicrobial Guanidinylate Polycarbonates Show Oral In Vivo Efficacy Against Clostridioides Difficile.

The emerging antibiotic resistance has been named by the World Health Organization (WHO) as one of the top 10 threats to public health. Notably, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VREF) are designated as serious threats, whereas Clostridioides difficile (C. difficile) is recognized as one of the most urgent threats to human health and unmet medical need. Herein, they report the design and application of novel biodegradable polymers - the lipidated antimicrobial guanidinylate polycarbonates. These polymers showed potent antimicrobial activity against a panel of bacteria with fast-killing kinetics and low resistance development tendency, mainly due to their bacterial membrane disruption mechanism. More importantly, the optimal polymer showed excellent antibacterial activity against C. difficile infection (CDI) in vivo via oral administration. In addition, compared with vancomycin, the polymer demonstrated a much-prolonged therapeutic effect and virtually diminished recurrence rate of CDI. The convenient synthesis, easy scale-up, low cost, as well as biodegradability of this class of polycarbonates, together with their in vitro broad-spectrum antimicrobial activity and orally in vivo efficacy against CDI, suggest the great potential of lipidated guandinylate polycarbonates as a new class of antibacterial biomaterials to treat CDI and combat emerging antibiotic resistance.

A Modular Microfluidic Organoid Platform Using LEGO-Like Bricks.

The convergence of organoid and organ-on-a-chip (OoC) technologies is urgently needed to overcome limitations of current 3D in vitro models. However, integrating organoids in standard OoCs faces several technical challenges, as it is typically laborious, lacks flexibility, and often results in even more complex and less-efficient cell culture protocols. Therefore, specifically adapted and more flexible microfluidic platforms need to be developed to facilitate the incorporation of complex 3D in vitro models. Here, a modular, tubeless fluidic circuit board (FCB) coupled with reversibly sealed cell culture bricks for dynamic culture of embryonic stem cell-derived thyroid follicles is developed. The FCB is fabricated by milling channels in a polycarbonate (PC) plate followed by thermal bonding against another PC plate. LEGO-like fluidic interconnectors allow plug-and-play connection between a variety of cell culture bricks and the FCB. Lock-and-play clamps are integrated in the organoid brick to enable easy (un)loading of organoids. A multiplexed perfusion experiment is conducted with six FCBs, where thyroid organoids are transferred on-chip within minutes and cultured up to 10 d without losing their structure and functionality, thus validating this system as a flexible, easy-to-use platform, capable of synergistically combining organoids with advanced microfluidic platforms.

Aliphatic Hyperbranched Polycarbonates Solid Polymer Electrolytes with High Li-Ion Transference Number for Lithium Metal Batteries.

In this work, hyperbranched polycarbonate-poly(ethylene oxide) (PEO)-based solid polymer electrolytes (HBPC-SEs) are successfully synthesized via a straightforward organo-catalyzed "A1"+"B2"-ring-opening polymerization approach. The temperature-dependent ionic conductivity of HBPC-SEs, composed of different polycarbonate linkages and various LiTFSI concentrations, is investigated. The results demonstrate that HBPC-SE with an ether-carbonate alternating structure exhibits superior ionic conductivity, attributed to the solubility of Li salts in the polymer matrix and the mobility of the polymer segments. The HBPC1-SE with 30 wt% LiTFSI presents the highest ionic conductivities of 2.15  × 10-5, 1.78 × 10-4, and 6.07 × 10-4 Scm-1 at 30, 60, and 80 °C, respectively. Compared to traditional PEO-based electrolytes, the incorporation of polycarbonate segments significantly enhances the electrochemical stability window (5 V) and Li+ transference number (0.53) of HBPC-SEs. Furthermore, the LiFePO4/HBPC1-SE-3/Li cell exhibits exceptional rate capability and long-cycling performance, maintaining a discharge capacity of 130 mAh g-1 at 0.5C with a capacity retention of 95% after 300 cycles.

Green Synthesis of UV-Reactive Polycarbonates from Levoglucosenone and 5-Hydroxymethyl Furfural.

This study focuses on the synthesis of fully renewable polycarbonates (PCs) starting from cellulose-based platform molecules levoglucosenone (LGO) and 2,5-bis(hydroxymethyl)furan (BHMF). These unique bio-based PCs are obtained through the reaction of a citronellol-containing triol (Triol-citro) derived from LGO, with a dimethyl carbonate derivative of BHMF (BHMF-DC). Solvent-free polymerizations are targeted to minimize waste generation and promote an eco-friendly approach with a favorable environmental factor (E-factor). The choice of metal catalyst during polymerization significantly influences the polymer properties, resulting in high molecular weight (up to 755 kDa) when Na2 CO3 is employed as an inexpensive catalyst. Characterization using nuclear magnetic resonance confirms the successful incorporation of the furan ring and the retention of the terminal double bond of the citronellol pendant chain. Furthermore, under UV irradiation, the presence of both citronellol and furanic moieties induces singular structural changes, triggering the formation of three distinct structures within the polymer network, a phenomenon herein occurs for the first time in this type of polymer. These findings pave the way to new functional materials prepared from renewable monomers with tunable properties.

De novo design of a polycarbonate hydrolase.

Enzymatic degradation of plastics is currently limited to the use of engineered natural enzymes. As of yet, all engineering approaches applied to plastic degrading enzymes retain the natural $\alpha /\beta $-fold. While mutations can be used to increase thermostability, an inherent maximum likely exists for the $\alpha /\beta $-fold. It is thus of interest to introduce catalytic activity toward plastics in a different protein fold to escape the sequence space of plastic degrading enzymes. Here, a method for designing highly thermostable enzymes that can degrade plastics is described. With the help of Rosetta an active site catalysing the hydrolysis of polycarbonate is introduced into a set of thermostable scaffolds. Through computational evaluation, a potential PCase was selected and produced recombinantly in Escherichia coli. Thermal analysis suggests that the design has a melting temperature of >95$^{\circ }$C. Activity toward polycarbonate was confirmed using atomic force spectroscopy (AFM), proving the successful design of a PCase.

A Simple, Selective, and General Catalyst for Ring Closing Depolymerization of Polyesters and Polycarbonates for Chemical Recycling.

The ability to efficiently and selectively process mixed polymer waste is important to address the growing plastic waste problem. Herein, we report that the combination of ZnCl2 and an additive amount of poly(ethylene glycol) under vacuum can readily and selectively depolymerize polyesters and polycarbonates with high ceiling temperatures (Tc >200 °C) back to their constitute monomers. Mechanistic experiments implicate a random chain scission mechanism and a catalyst structure containing one equivalent of ZnCl2 per ethylene glycol repeat unit in the poly(ethylene glycol). In addition to being general for a wide variety of polyesters and polycarbonates, the catalyst system could selectively depolymerize a polyester in the presence of other commodity plastics, demonstrating how reactive distillation using the ZnCl2 /PEG600 catalyst system can be used to separate mixed plastic waste.

Robust Construction of Supersmall Zwitterionic Micelles Based on Hyperbranched Polycarbonates Mediates High Tumor Accumulation.

Despite the numerous advantages of nanomedicines, their therapeutic efficacy is hampered by biological barriers, including fast in vivo clearance, poor tumor accumulation, inefficient penetration, and cellular uptake. Herein, cross-linked supersmall micelles based on zwitterionic hyperbranched polycarbonates can overcome these challenges for efficiently targeted drug delivery. Biodegradable acryloyl/zwitterion-functionalized hyperbranched polycarbonates are synthesized by a one-pot sequential reaction of Michael-type addition and ring-opening polymerization, followed by controlled modification with carboxybetaine thiol. Cross-linked supersmall zwitterionic micelles (X-CBMs) are readily prepared by straightforward self-assembly and UV cross-linking. X-CBMs exhibit prolonged blood circulation because of their cross-linked structure and zwitterion decoration, which resist protein corona formation and facilitate escaping RES recognition. Combined with the advantage of supersmall size (7.0 nm), X-CBMs mediate high tumor accumulation and deep penetration, which significantly enhance the targeted antitumor outcome against the 4T1 tumor model by administration of the paclitaxel (PTX) formulation (X-CBM@PTX).

Transmission of poly(dT60 ) single-stranded DNA through polycarbonate track-etched ultrafiltration membranes.

The objective of this study was to examine membrane filtration of a single stranded DNA (ssDNA) with 60 thymine nucleotides, and to elucidate the variables controlling its transmission across track-etched porous membranes. Dead end filtration measurements were performed using different pore size membranes (10, 15, and 30 nm) at different transmembrane pressures in solutions with ionic strength ranging from 0 to 1000 mM NaCl. The diffusivity of the ssDNA was determined using fluorescence recovery after photobleaching, yielding hydrodynamic radii ranging from 1.6 to 2.8 nm, with values decreasing with increasing solution ionic strength. Despite the small ssDNA/membrane pore size, nearly 100% rejection was observed for measurements performed with the 10 and 15 nm pore size membranes under low-ionic strength conditions. These high rejections can be attributed to strong repulsive electrostatic ssDNA-membrane interactions. With increasing ionic strength, electrostatic interactions as well as the effective size of the ssDNA decreases and the flexibility of the ssDNA increases, leading to a reduction in ssDNA rejection. A design of experiments approach was used to plan filtration experiments that adequately covered the variable space with a manageable number of experiments. The results yielded an empirical expression relating ssDNA rejection to pore size, solution ionic strength and transmembrane pressure. There was evidence of flow induced elongation at high-transmembrane pressures in the 30 nm pore size membranes, but not in the smaller pore size membranes. These results are consistent with critical flux estimates developed using a free draining model for the ssDNA.

Effect of Vent Hole and Cement Type on Fracture Resistance of CAD-CAM Monolithic Zirconia Crowns.

PURPOSE: To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement-retained implant abutments. MATERIALS AND METHODS: Forty implant analogs were positioned in acrylic resin blocks, and cement-retained straight implant abutments were fastened to the analogs. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD-CAM technique. The two crown types were divided into two groups and cemented with resin and zinc-polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analyzed using two-way ANOVA and the independent samples t-test with statistical significance set at p < 0.05. RESULTS: According to the two-way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ± 337.39 N, 1565.16 ± 517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc-polycarboxylate cement (1680.1 ± 375.23 N) showed higher fracture resistance than resin cement (1302.71 ± 420.64 N) in the crowns designed with vent holes (p < 0.005). CONCLUSION: The use of cement-retained implant-supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc-polycarboxylate cement use may be an appropriate choice for cementation of these crowns.

Enhanced drug delivery to cancer cells through a pH-sensitive polycarbonate platform.

Polymer-drug conjugates are widely investigated to enhance the selectivity of therapeutic drugs to cancer cells, as well as increase circulation lifetime and solubility of poorly soluble drugs. In order to direct these structures selectively to cancer cells, targeting agents are often conjugated to the nanoparticle surface as a strategy to limit drug accumulation in non-cancerous cells and therefore reduce systemic toxicity. Here, we report a simple procedure to generate biodegradable polycarbonate graft copolymer nanoparticles that allows for highly efficient conjugation and intracellular release of S-(+)-camptothecin, a topoisomerase I inhibitor widely used in cancer therapy. The drug-polymer conjugate showed strong efficacy in inhibiting cell proliferation across a range of cancer cell lines over non-cancerous phenotypes, as a consequence of the increased intracellular accumulation and subsequent drug release specifically in cancer cells. The enhanced drug delivery towards cancer cells in vitro demonstrates the potential of this platform for selective treatments without the addition of targeting ligands.

Investigation of neural electrode fabrication process on Polycarbonate substrate.

Polycarbonate is a polymer that has been widely used including medical application due to its useful properties. It has high temperature resistance, biocompatibility, transparency and low water absorption rate, which are needful characteristics for packaging material of implantable neural prosthetic devices. In this study, we investigated fabrication of neural electrode with polycarbonate film using standard photolithography process and heated hydraulic press for thermal lamination. First, oxygen plasma surface treatment was performed to increase the adhesion between metal and polycarbonate film. Then thin layer of titanium and gold layer were deposited. Metal layer is patterned through standard photolithography techniques. After completing the metal patterning, thermal lamination was performed with site opened polycarbonate film.

An approach to removing COD and BOD based on polycarbonate mixed matrix membranes that contain hydrous manganese oxide and silver nanoparticles: A novel application of artificial neural network based simulation in MATLAB.

This study aimed to determine the efficacy of novel ultrafiltration and mixed matrix membrane (MMM) composed of hydrous manganese oxide (HMO) and silver nanoparticles (Ag-NPs) for the removal of biological oxygen demand (BOD) and chemical oxygen demand (COD). In the polycarbonate (PC) MMM, the weight percent of HMO and Ag-NP has been increased from 5% to 10%. A neural network (ANN) was used in this study to compare PC-HMO and Ag-NP. MMM was evaluated in combination with HMO and Ag-NP loadings in order to assess their effects on pure water flux, mean pore size, porosity, and efficacy in removing BOD and COD. HMO and Ag-NPs can decrease membrane porosity in the casting solution while increasing mean pore size. According to the study's findings, the artificial neural network model appears to be highly appropriate for predicting the removal of BOD and COD. To develop a successful model, a suitable input dataset was selected, which consisted of BOD and COD. An ideal model architecture for MMM was proposed based on an optimal number of hidden layers (2 layers) and neurons (5-8 neurons). Experiments and predicted data show a strong correlation between the developed models. BOD was predicted with an excellent R2 and a low root mean square error (RMSE) of 0.99 and 0.05%, respectively, while COD was predicted with an excellent R2 and a low RMSE of 0.99 and 0.09%, respectively. Based on the results, Ag-NP was found to be an excellent candidate for the preparation of MMMs as well as convenient for the removal of BOD and COD from polluted water sources.

Solid-State Chemical Recycling of Polycarbonates to Epoxides and Carbon Dioxide Using a Heterodinuclear Mg(II)Co(II) Catalyst.

Polymer chemical recycling to monomers (CRM) could help improve polymer sustainability, but its implementation requires much better understanding of depolymerization catalysis, ensuring high rates and selectivity. Here, a heterodinuclear [Mg(II)Co(II)] catalyst is applied for CRM of aliphatic polycarbonates, including poly(cyclohexene carbonate) (PCHC), to epoxides and carbon dioxide using solid-state conditions, in contrast with many other CRM strategies that rely on high dilution. The depolymerizations are performed in the solid state giving very high activity and selectivity (PCHC, TOF = 25700 h-1, CHO selectivity >99 %, 0.02 mol %, 140 °C). Reactions may also be performed in air without impacting on the rate or selectivity of epoxide formation. The depolymerization can be performed on a 2 g scale to isolate the epoxides in up to 95 % yield with >99 % selectivity. In addition, the catalyst can be re-used four times without compromising its productivity or selectivity.

Eugenol-derived Organic Liquids as an In-Situ CO2 Capturing and Conversion System for Eugenol-based Polycarbonate Synthesis.

The significant development of catalytic biomass conversion has provided a large library of chemicals ready for subsequent upgrading to polymerisable monomers for the design and preparation of sustainable polymers. In this study, hydroxyethylation of eugenol by using green ethylene carbonate as alkylation reagent and cheap tetrabutylammonium iodide ionic liquids as green solvents and catalysts produced 2-(4-allyl-2-methoxyphenoxy)ethan-1-ol with a 85% yield, which could be used to construct an in situ CO2 capture and conversion system by taking the reversible chemistry of alcoholic compounds with CO2 in the presence of superbases, on which α,ω-diene functionalized carbonate monomers were successfully prepared and were applied in thiol-ene click and acyclic diene metathesis polymerisation (ADMET), producing a series of poly(thioether carbonate)s and unsaturated aromatic aliphatic polycarbonates with moderate molecular weights and satisfactory thermal properties. The structures of the formed CO2 reversible ILs, the polymerisable monomers and the corresponding polymers were fully characterized by various technologies.