Hyperbranched polymer micelles with triple-stimuli backbone-breakable iminoboronate ester linkages

ortho-Boronic Acid Carbonyl Compounds and Their Applications in Chemical Biology

Iminoboronates and diazaborines are related classes of compounds that feature an imine ortho to an arylboronic acid (iminoboronate) or a hydrazone that cyclizes with an ortho arylboronic acid (diazaborine). Rather than acting as independent chemical motifs, the arylboronic acid impacts the rate of imine/hydrazone formation, hydrolysis, and exchange with competing nucleophiles. Increasing evidence has shown that the imine/hydrazone functionality also impacts arylboronic acid reactivity toward diols and reactive oxygen and nitrogen species (ROS/RNS). Untangling the communication between C=N linked functionalities and arylboronic acids has revealed a powerful and tunable motif for bioconjugation chemistries and other applications in chemical biology. Here, we survey the applications of iminoboronates and diazaborines in these fields with an eye toward understanding their utility as a function of neighboring group effects.

Hyperbranched Conjugated Polymer with Multiple Charge Transfer Enables High-Efficiency Nondoped Red Electroluminescence with Low Driving Voltage

Conjugated polymers featuring thermally activated delayed fluorescence (TADF) attract tremendous attention in both academic and industry communities due to their easy solution processing for fabricating large-area and low-cost high-performance polymer light-emitting diodes (PLEDs). However, current nondoped solution-processed PLEDs frequently encounter significant efficiency roll-offs and unreasonably high operating voltages at high brightness, especially for red-emitting polymers. Herein, we design hyperbranched conjugated polymers (HCPs) with D-A-D type TADF characteristics for high-performance red-emitting PLEDs. Multiple intramolecular charge transfer (ICT) channels induced by quasi-equivalent donors of the TADF core strongly boost the reverse intersystem crossing (RISC) process and singlet excitons radiative transition. Coupling with the efficient energy transfer process generated by structure advantages of HCPs, the strongly electron-withdrawing oxygen atoms located on the TADF cores further accelerate hole transportation from the host chains to the TADF cores. Under a rational regulation of the TADF core ratio, the related nondoped red-emitting device performs an outstanding performance with an EQE_max of 8.39% and exhibits no roll-off while the luminance is less than 100 cd/m² and only 3.3% decrease at 500 cd/m². Simultaneously, the EQE can maintain 7.4% under 1000 cd/m². Furthermore, the corresponding nondoped device exhibits a low turn-on voltage of around 2.5 V and achieves a luminance of 500 cd/m² at 3.5 V and even 1000 cd/m² at 3.9 V. To our knowledge, this is the best performance among all nondoped red PLEDs with high brightness obtained at low operating voltage.

Covalent adaptable networks using boronate linkages by incorporating TetraAzaADamantanes

Boronic esters prepared by condensation of boronic acids and diols have been widely used as dynamic covalent bonds in the synthesis of both discrete assemblies and polymer networks. In this study we investigate the potential of a new dynamic-covalent motif, derived from TetraAzaADamantanes (TAADs), with their adamantane-like triol structure, in boronic ester-based covalent adaptable networks (CANs). The TetraAzaADamantane-boronic ester linkage has recently been reported as a more hydrolytically stable boronic ester variant, while still having a dynamic pH response: small-molecule studies found little exchange at neutral pH, while fast exchange occurred at pH 3.8. In this work, bi- and trifunctional TetraAzaADamantane linkers were synthesised and crosslinked with boronic acids to form rubber-like materials, with a Young's modulus of 1.75 MPa. The dynamic nature of the TetraAzaADamantane networks was confirmed by stress relaxation experiments, revealing Arrhenius-like behaviour, with a corresponding activation energy of 142 ± 10 kJ/mol. Increasing the crosslinking density of the material from 10% to 33% resulted in reduced relaxation times, as is consistent with a higher degree of crosslinking within the dynamic networks. In contrast to the reported accelerating effect of acid addition to small-molecule TetraAzaADamantane complexes, within the polymer network the addition of acid increased relaxation times, suggesting unanticipated interactions between the acid and the polymer that cannot occur in the corresponding small-molecules analogues. The obtained boronate-TetraAzaADamantane materials were thermally stable up to 150°C. This thermal stability, in combination with the intrinsically dynamic bonds inside the polymer network, allowed these materials to be reprocessed and healed after damage by hot-pressing.

Research on Mechanism of Nanometric Bone Pulp Activated with Double Gene as Bone Morphogenetic Protein 1 and Vascular Endothelial Growth Factor for Improving the Strength of Centrum in Osteoporosis

The aim of this study was assessing the mechanism of nanometric bone pulp activated with double gene as bone morphogenetic protein 1 (BMP-1) and vascular endothelial growth factor (VEGF) in improving the strength of centrum in osteoporosis (OP). The model of nanometric bone pulp activated with BMP-1 and VEGF double gene was established and validated. Under maximum condition of load and collapsed fragments, the model was analyzed through biomechanical test. The conditions for ALP, BGP, MLL and BMD in the model were also analyzed, and three-dimensional structural transformation was analyzed. Western blot and qRT-PCR were used to detect the effect of adding or not adding dual gene activated nano-bone stickers on OC-specific protein and mRNA; ELISA kits were used to detect the changes of RANKL pathway RANKL, OPG and TRACP5b. The maximum conformed quality and condensed intensity were strengthened with the nanometric bone pulp activated with BMP-1 and VEGF double gene. The maximum load in centrum was extremely elevated in the model, and the condition of ALP and its effect on bone was partly improved in the model. The precision and efficiency in the quality of BMD were continuously decreased. The BMD and MLF were strengthened notably in the model, and their effect on the bone was extremely improved. There was tight displayed model of trabecular in centrum and porosity was also continuously reduced. After adding the double-gene activated nano-bone stickers, the results from qRTPCR and Western blot showed that the changes of osteoclast-related genes and protein expressions were significantly down-regulated. The nanometric bone pulp activated with BMP-1 and VEGF double gene was one of ideal filled criterion. The BMD and bone strength were also elevated.

An injectable self-adaptive polymer as a drug carrier for the treatment of nontraumatic early-stage osteonecrosis of the femoral head

Core decompression (CD) with the elimination of osteonecrotic bone is the most common strategy for treating early-stage nontraumatic osteonecrosis of the femoral head (ONFH). Adjuvant treatments are widely used in combination with CD as suitable methods of therapy. Existing augmentations have to be fabricated in advance. Here, we report a novel injectable glycerin-modified polycaprolactone (GPCL) that can adapt to the shape of the CD cavity. GPCL shows great flowability at 52.6 °C. After solidification, its compressive modulus was 120 kPa at body temperature (37 °C). This excellent characteristic enables the polymer to provide mechanical support in vivo. In addition, GPCL acts as a carrier of the therapeutic agent zoledronic acid (ZA), demonstrating sustained release into the CD region. ZA-loaded GPCL was injected into ONFH lesions to treat early-stage nontraumatic cases. Compared to that in the CD group, CD+ZA-loaded GPCL injection preserved bone density and increased the collagen level in the femoral head. At the interface between the GPCL and CD tunnel wall, osteogenesis was significantly promoted. In addition, morphological evaluations revealed that the femoral heads in the CD+ZA-GPCL group exhibited improved pressure resistance. These results suggest a strategy effective to preserve the bone density of the femoral head, thus decreasing the possibility of femoral head collapse. This novel injectable polymer has, therefore, considerable potential in clinical applications.

Physicochemical Characterization and Pharmacological Evaluation of Novel Propofol Micelles with Low-Lipid and Low-Free Propofol

We developed safe and stable mixed polymeric micelles with low lipids and free propofol for intravenous administration, to overcome the biological barrier of the reticuloendothelial system (RES), reduce pain upon injection, and complications of marketed propofol formulation. The propofol-mixed micelles were composed of distearoyl-phosphatidylethanolamine-methoxy-poly (ethylene glycol 2000) (DSPE mPEG2k) and Solutol HS 15 and were optimized using Box Behnken design (BBD). The optimized formulation was evaluated for globule size, zeta potential, loading content, encapsulation efficiency, pain on injection, histological evaluation, hemolysis test, in vivo anesthetic action, and pharmacokinetics, in comparison to the commercialized emulsion Diprivan. The optimized micelle formulation displayed homogenous particle sizes, and the free drug concentration in the micelles was 60.9% lower than that of Diprivan. The paw-lick study demonstrated that propofol-mixed micelles significantly reduced pain symptoms. The anesthetic action of the mixed micelles were similar with the Diprivan. Therefore, we conclude that the novel propofol-mixed micelle reduces injection-site pain and the risk of hyperlipidemia due to the low content of free propofol and low-lipid constituent. It may be a more promising clinical alternative for anesthetic.

Polymers with multiple functions: α,ω-macromolecular photoinitiators/chain transfer agents used in aqueous photoinitiated polymerization-induced self-assembly

A series of α,ω-functionalized polymers with a photoinitiator end group and a RAFT end group were synthesized and employed as macromolecular photoinitiators/chain transfer agents in aqueous photoinitiated polymerization-induced self-assembly.

The modern role of boron as a 'magic element' in biomedical science: chemistry perspective

Boron was misconstrued as a toxic element for animals, which retarded the growth of boron-containing drug discovery in the last century. Nevertheless, modern applications of boronic acid derivatives are attractive in biomedical applications after the declaration that boron is a 'probable essential element' for humans by the WHO. Additionally, the approval of five boronic acid-containing drugs by the FDA has vastly impacted the use of boron in medicinal chemistry, chemical biology, drug delivery, biomaterial exploration, pharmacological improvements, and nutrition. This review article focuses on the chemistries attributed to boronic acids at physiological pH, enticing chemists to multidisciplinary applications. Prospective uses of boronic acid in pharma and chemical biology, along with prospects and challenges, are also part of the deliberation. Understanding these fundamental chemistries and interactions of boronic acid in biological systems will enable solving future challenges in drug discovery and executing space-age applications.

Boronic acid based dynamic click chemistry: recent advances and emergent applications

Recently, reversible click reactions have found numerous applications in chemical biology, supramolecular chemistry, and biomedical applications. Boronic acid (BA)-mediated cis-diol conjugation is one of the best-studied reactions among them. An excellent understanding of the chemical properties and biocompatibility of BA-based compounds has inspired the exploration of novel chemistries using boron to fuel emergent sciences. This topical review focuses on the recent progress of iminoboronate and salicylhydroxamic-boronate constituted reversible click chemistries in the past decade. We highlight the mechanism of reversible kinetics and its applications in chemical biology, medicinal chemistry, biomedical devices, and material chemistry. This article also emphasizes the fundamental reactivity of these two conjugate chemistries with assorted nucleophiles at variable pHs, which is of utmost importance to any stimuli-responsive biological and material chemistry explorations.