The incorporation of diverse macromolecular blocks into CO2-based polycarbonates offers a promising approach for tailoring the properties of polycarbonates for special needs. In this work, we report ...for the first time the synthesis and characterization of an ABA triblock copolymer polycarbonate-b-polyalkenamer-b-polycarbonate in combination of ROCOP and ROMP via a one-pot route from CO2, epoxides and cycloalkenes. Cis-2-butene-1,4-diol as the bifunctional chain transfer agent was used as a “bridge” for the combination of different blocks as well as an effective regulator for the molecular weight of the polymers. In the one-pot reaction, the conversion of cycloalkenes reached 99.9% within 0.5 h, while the conversion of CHO was initially marginal at 0.5% but gradually increased to 99.7% after 24 h. The significant discrepancy in reaction rates between the two processes enables efficient synergistic reactions within the one-pot system. Specifically, hydroxyl-telechelic polyalkenamer is initially formed via ROMP and subsequently acts as an active species for ROCOP when coordinated with the porphyrin Al catalyst. This one-pot strategy provides a unique and simple method for controllably constructing functional polycarbonates with single-modal molecular weight distributions. By integrating the advantages of polyalkenamers and polycarbonates, this approach proves to be a viable solution for addressing the unsatisfactory thermal properties of aliphatic polycarbonates.
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•CO2-based functional polycarbonate prepared via one pot reaction in combination of ROCOP and ROMP.•Bifunctional chain transfer agent as a bridge for polycarbonate and polyalkenamer to achieve block copolymer.•ABA block structure confirmed by 1H NMR, DOSY and MALDI-TOF analysis.
In this work, the flexibility of polycarbonate (PC) membrane was improved by using polyurethane (PU) additive. However, due to the hydrophobic nature of the PU polymer, alumina (Al2O3) nanoparticles ...were incorporated to PC‐PU blend membrane. The prepared membranes have been used in a submerged membrane system to eliminate humic acid molecules from polluted water in both the presence and absence of coagulant (polyaluminum chloride). The obtained results showed that introduction of PU into PC membrane diminished hydrophilicity and enhanced porosity. Moreover, the flexibility of the PC membrane remarkably improved. Introduction of 1.5 wt% Al2O3 to the PC‐PU blend membrane led to enhancement in both porosity and hydrophilicity. Results of morphological studies showed that in the presence of Al2O3 nanostructures, finger‐shaped voids seemed to elongate across the entire thickness of the prepared membrane. Atomic force microscopy images showed that incorporation of PU and Al2O3 to the PC membrane resulted in a smoother surface. The antifouling performance of membranes revealed that the PC‐PU/Al2O3 nanocomposite membrane possessed the most favorable antifouling features owing to its lowest surface roughness as well as highest hydrophilicity. For all membranes utilizing coagulant (PAC), the irreversible fouling ratio and the flux recovery ratio significantly diminished and increased, respectively.
Currently available focal knee resurfacing implants (FKRIs) are fully or partially composed of metals, which show a large disparity in elastic modulus relative to bone and cartilage tissue. Although ...titanium is known for its excellent osseointegration, the application in FKRIs can lead to potential stress‐shielding and metal implants can cause degeneration of the opposing articulating cartilage due to the high resulting contact stresses. Furthermore, metal implants do not allow for follow‐up using magnetic resonance imaging (MRI).To overcome the drawbacks of using metal based FKRIs, a biomimetic and MRI compatible bi‐layered non‐resorbable thermoplastic polycarbonate‐urethane (PCU)‐based FKRI was developed. The objective of this preclinical study was to evaluate the mechanical properties, biocompatibility and osteoconduction of a novel Bionate® 75D ‐ zirconium oxide (B75D‐ZrO2) composite material in vitro and the osseointegration of a B75D‐ZrO2 composite stem PCU implant in a caprine animal model. The tensile strength and elastic modulus of the B75D‐ZrO2 composite were characterized through in vitro mechanical tests under ambient and physiological conditions. In vitro biocompatibility and osteoconductivity were evaluated by exposing human mesenchymal stem cells to the B75D‐ZrO2 composite and culturing the cells under osteogenic conditions. Cell activity and mineralization were assessed and compared to Bionate® 75D (B75D) and titanium disks. The in vivo osseointegration of implants containing a B75D‐ZrO2 stem was compared to implants with a B75D stem and titanium stem in a caprine large animal model. After a follow‐up of 6 months, bone histomorphometry was performed to assess the bone‐to‐implant contact area (BIC). Mechanical testing showed that the B75D‐ZrO2 composite material possesses an elastic modulus in the range of the elastic modulus reported for trabecular bone. The B75D‐ZrO2 composite material facilitated cell mediated mineralization to a comparable extent as titanium. A significantly higher bone‐to‐implant contact (BIC) score was observed in the B75D‐ZrO2 implants compared to the B75D implants. The BIC of B75D‐ZrO2 implants was not significantly different compared to titanium implants. A biocompatible B75D‐ZrO2 composite approximating the elastic modulus of trabecular bone was developed by compounding B75D with zirconium oxide. In vivo evaluation showed an significant increase of osseointegration for B75D‐ZrO2 composite stem implants compared to B75D polymer stem PCU implants. The osseointegration of B75D‐ZrO2 composite stem PCU implants was not significantly different in comparison to analogous titanium stem metal implants.
The alternating copolymerization of biorenewable limonene dioxide with carbon dioxide (CO2) catalyzed by a zinc β‐diiminate complex is reported. The chemoselective reaction results in linear ...amorphous polycarbonates that carry pendent methyloxiranes and exhibit glass transition temperatures (Tg) up to 135 °C. These polycarbonates can be efficiently modified by thiols or carboxylic acids in combination with lithium hydroxide or tetrabutylphosphonium bromide as catalysts, respectively, without destruction of the main chain. Moreover, polycarbonates bearing pendent cyclic carbonates can be quantitatively prepared by CO2 insertion catalyzed by lithium bromide.
From biobased diepoxide to linear epoxy PCs: A sustainable poly(limonene‐8,9‐oxide carbonate) was prepared by chemoselective copolymerization of limonene dioxide and CO2. The pendent 2‐methyloxiranyl groups along the polymer chain permit the facile post‐modification and insertion of CO2 to generate cyclic carbonates as functional side groups.
From an industrial/engineering point of view, the greatest demerit of solely isosorbide (ISB)-based polycarbonate is its fragility; this is considerably overcome in this study by using a dual-diol ...strategy with 1,4-cyclohexanedimethanol (CHDM). A series of copolycarbonates of ISB, a bio-derived diol with a rigid heterocyclic structure, and ductile CHDM monomers with diphenyl carbonate were prepared by transesterification polymerization. The weight-average molecular weight of the polycarbonates gradually decreases as the ratio of ISB increases; however, their Tg and storage modulus increase. The ultimate elongation of the copolycarbonates is enhanced from 4.6 to 20% as the content of CHDM is increased from 30 to 80 mol%. ISB content greater than 50 mol% makes the copolycarbonates strong but brittle, and ISB content less than 50 mol% makes the copolycarbonates ductile but soft. The polycarbonate with 70/30 mol% of ISB/CHDM shows a 1.25-fold higher Young's modulus, 1.05-fold higher ultimate tensile strength, and one-grade higher pencil hardness than the bisphenol-A (BPA)-based polycarbonate. Interestingly, the hydrophilic ISB content does not affect the degree of hydrophilicity of the copolycarbonate samples. Water droplet contact angles are in the range of 81–87°, comparable to that of the BPA-based polycarbonate.
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•Synthesis of copolycarbonates of bio-based isosorbide and 1,4-cyclohexanedimethanol.•As the isosorbide content increased, Tg and the degree of elasticity increased.•Mechanical properties were tuned from ductile to strong by varying ISB/CHDM ratios.•1.25-fold higher Young's modulus, higher pencil hardness than the BPA-polycarbonate.•Comparable hydrophilicity of copolycarbonates with the BPA-polycarbonate.
An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as ...biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The negatively-charged HPV DNA oligonucleotides under external electric field were oriented in a preferred direction and the bio-sensing responses were intensified by controlling the immobilization and hybridization of the sequences on the AuNTs surface. The fabricated DNA biosensor under electric field amplification was stable up to six weeks and demonstrated 97% of its initial detection responses. The biosensor displayed the HPV DNA hybridization detection in very low concentrations in the linear response ranges of 0.01 pM–1 μM and was able to acquire a limit of detection (LOD) of 1 fM.
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•Impedimetric human papillomavirus DNA biosensor by AuNTs-PC electrode was fabricated.•The EIS response was intensified by AuNTs and electric field to acquire LOD of 1fM.•Biosensor in label free detection showed the good linear ranges of 0.01pM to 1μM.•Biosensor could highly specify ds-DNA from the mismatch and non-complementary targets.•Biosensor was stable up to 6 weeks and showed 97% of its initial detection responses.
Abstract
3D printing has emerged as one of the most promising tools to overcome the processing and morphological limitations of traditional tissue engineering scaffold design. However, there is a ...need for improved minimally invasive, void-filling materials to provide mechanical support, biocompatibility, and surface erosion characteristics to ensure consistent tissue support during the healing process. Herein, soft, elastomeric aliphatic polycarbonate-based materials were designed to undergo photopolymerization into supportive soft tissue engineering scaffolds. The 4D nature of the printed scaffolds is manifested in their shape memory properties, which allows them to fill model soft tissue voids without deforming the surrounding material. In vivo, adipocyte lobules were found to infiltrate the surface-eroding scaffold within 2 months, and neovascularization was observed over the same time. Notably, reduced collagen capsule thickness indicates that these scaffolds are highly promising for adipose tissue engineering and repair.
Intratumor microbes have attracted great attention in cancer research due to its influence on the tumorigenesis, progression and metastasis of cancer. However, the therapeutic strategies targeting ...intratumoral microbes are still in their infancy. Specific microorganisms, such as Fusobacterium nucleatum (F. nucleatum), are abundant in various cancer and always result in the CRC progression and chemotherapy resistance. Here, a combined anticancer and antibacterial therapeutic strategy is proposed to deliver antitumor drug to the tumors containing intratumor microbiota by the antibacerial polymeric drug carriers. We construct oral tellurium-containing drug carriers using a complex of tellurium-containing polycarbonate with cisplatin (PTE@CDDP). The results show that the particle size of the prepared nanoparticles could be maintained at about 105 nm in the digestive system environment, which is in line with the optimal particle size of oral nanomedicine. In vitro mechanism study indicates that the tellurium-containing polymers are highly effective in killing F.nucleatum through a membrane disruption mechanism. The pharmacokinetic experiments confirmed that PTE@CDDP has the potential function of enhancing the oral bioavailability of cisplatin. Both in vitro and in vivo studies show that PTE@CDDP could inhibit intratumor F.nucleatum and lead to a reduction in cell proliferation and inflammation in the tumor site. Together, the study identifies that the CDDP-loaded tellurium-containing nanoparticles have great potential for treating the F.nucleatum-promoted colorectal cancer (CRC) by combining intratumor microbiota modulation and chemotherapy. The synergistic therapeutic strategy provide new insight into treating various cancers combined with bacterial infection.
The synthesized antibacterial polymer was first employed to remodel the intratumor microbes in tumor microenvironment (TME). Moreover, it was the first report of tellurium-containing polymers against F.nucleatum and employed for treatment of the CRC. A convenient oral dosage form of cisplatin (CDDP)-loaded tellurium-containing nanoparticles (PTE@CDDP) was adopted here, and the synergistic antibacterial/chemotherapy effect occurred. The PTE@CDDP could quickly and completely eliminate F.nucleatum in a safe dose. In the CRC model, PTE@CDDP effectively reversed the inflammation level and even restored the intestinal barrier damaged by F.nucleatum. The ultrasensitive ROS-responsiveness of PTE@CDDP triggered the fast oxidation and efficient drug release of CDDP and thus a highly efficient apoptosis of the tumors. Therefore, the tellurium-containing polymers are expected to serve as novel antibacterial agents in vivo and have great potential in the F.nucleatum-associated cancers. The achievements provided new insight into treating CRC and other cancers combined with bacterial infection.
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Various polycarbonate ‐ poly(butylene terephthalate) polyester (PC‐PBT) blend prepared by reactive melt blending primarily in extruder with range of temperature and time are discussed in this review ...article. In the melt blended PC‐PBT blend system, transesterification plays a major role in formation of PC‐PBT blend. Transesterification reactions between these two polymers have been analyzed by proper polymer sample, end‐capped or having reactive chain end group. The kinetics of mechanism is a function of temperature and PC‐PBT ratio. Trace catalyst residue present in PBT catalyzes the transesterification reaction. As the extent of transesterification is increased, it forms various composition of copolymer. Inhibition in the transesterification reaction of PC‐PBT blend has been observed when different type of alkyl, aryl, and alkyl‐aryl group of phosphite are introduced into it, otherwise there has been collateral change in the morphology, thermal, and mechanical property of blend. Therefore, this PC‐PBT blend has been an interesting topic of research in academia and industries.
Schematic representation of chronology of transesterification reaction between polycarbonate and poly(butylene terephthalate)
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