Latest ArticlesNanocarriers play an important role in drug delivery for disease treatment. However, nanocarriers face a series of physiological barriers after administration such as blood clearance, nonspecific tissue/cell localization, poor cellular uptake, and endosome trapping. These physiological barriers seriously reduce the accumulation of drugs in target action site, which results in poor therapeutic efficiency. Although polyethylene glycol (PEG) can increase the blood circulation time of nanocarriers, its application is limited due to the "PEG dilemma". Zwitterionic polymers have been emerging as an appealing alternative to PEG owing to their excellent performance in resisting nonspecific protein adsorption. Importantly, the diverse structures bring functional versatility to zwitterionic polymers beyond nonfouling. This review focuses on the structures and characters of zwitterionic polymers, and will discuss and summarize the application of zwitterionic polymers for drug delivery. We will highlight the strategies of zwitterionic polymers to address the physiological barriers during drug delivery. Finally, we will give some suggestions that can be utilized for the development of zwitterionic polymers for drug delivery. This review will also provide an outlook for this field. Our aim is to provide a comprehensive and systemic review on the application of zwitterionic polymers for drug delivery and promote the development of zwitterionic polymers.
A pair of selenanthrene-bridged molecular cages have been constructed through a one-step cyclization reaction of a tetrakis(iodo) crown ether with selenium powder. The tubular belt-shaped cage has an intrinsic cavity which can adaptively transform to accommodate electron-deficient guests forming [2]pseudorotaxane complexes. The other product was determined to be an isomeric cage featuring a Möbius strip structure, which exhibits slower twist-migration dynamics than its thianthrene counterpart. The success of using selenanthrene as joints enables an alternative way to structural design and property regulation of molecular cages.
The d-band centers of catalysts have exhibited excellent performance in various reactions. Among them, the enhanced catalytic reaction is considered a crucial way to power dynamics and reduce the "shuttle" effect in polysulfide conversions of lithium-sulfur batteries. Here, we report two-dimensional-shaped tungsten borides (WB) nanosheets with d-band centers, where the d orbits of W atoms on the (001) facets show greatly promoting the electrocatalytic sulfur reduction reaction. As-prepared WB-based Li-S cells exhibit excellent electrochemical performance for Li-ion storage. Especially, it delivers superior capacities of 7.7 mAh/cm2 under the 8.0 mg/cm2 sulfur loading, which is far superior to most other electrode catalysts. This study provides insights into the d-band centers as a promising catalyst of two-dimensional boride materials
The undesirable shuttle effect and sluggish redox kinetics of polysulfides seriously result in low sulfur utilization and poor capacity retention. Here, an integrated strategy is proposed by rational designing multifunctional architecture to manipulate the redox kinetics of polysulfides, specifically, by employing iron atoms (Fe-As) and iron-species nanoparticles (Fe-NPs) co-embedded nitrogen-doped carbon nanotube (Fe-NCNT) as catalyst and host for sulfur. The synergistic cooperation of Fe-As and Fe-NPs provides efficient active sites to facilitate the diffusion, strengthen the affinities, and promote the conversion reactions for polysulfides. Furthermore, the NCNT not only offers practical Li+ transport pathways but also immobilize the polysulfides effectively. Benefiting from these merits, the Fe-NCNT/S electrodes exhibit high initial specific capacity of 1502.6 mAh/g at 0.1 C, outstanding rate performance (830 mAh/g at 2 C), and good cycling performance (597.8 mAh/g after 500 cycles with an ultralow capacity fading rate of 0.069% per cycle). This work features the distinct interaction of iron atom-nanoparticles on facilitating immobilization-diffusion-transformation process of polysulfides, and it also expected to pave the way for the application in practical Li-S batteries.
Silver selenide thin film is one of the best candidates for thermoelectric devices. In the previous report, we demonstrated that high-performanced [201] oriented β-Ag2Se thin films can be prepared by direct metal surface element reaction (DMSER) solution selenization in a really short time at room temperature. However, the underlying mechanism of the fast reaction process were not discussed in depth. Herein, based on hard soft acid base (HASB) theory and strong oxidation, we further explored the possible reaction mechanism of the in-situ growth of β-Ag2Se thin films as the function of the reaction time. The time-dependent experimental results showed that the formation of the β-Ag2Se on elemental Ag precursor (~690 nm thick) in Se/Na2S precursor solution is in a growth driven mode with no obvious orientation or growth rate selections to the elemental Ag precursors. Our investigations provide a prerequisite for the further preparation of thermoelectric materials with excellent properties.
With the development of a small interfering RNA (siRNA) delivery strategy, increasing siRNA therapeutics for tumor treatment appeared in clinical trials and pre-clinical development. However, the test results of such therapeutics unveiled that efficient siRNA delivery to tumor tissues is still challenging. Albumin is considered an ideal carrier for delivering hydrophobic agents into tumor tissue because it is highly concentrated and long-circulating in blood and has propensity of tumor enrichment. Herein, we synthesized lipid conjugated siRNAs (LsiRNAs), which showed high affinity to albumin. Mechanistically, LsiRNAs non-covalently bind to the hydrophobic core of albumin through its octadecyl tails. The small size of albumin/LsiRNAs allows the complex to penetrate tumor tissue efficiently. Biodistribution test proved that albumin extremely prolonged circulation time and increased tumor retention of associated LsiRNAs. Notably, LsiRNA against programmed death ligand-1 (Pdl1) efficiently suppressed tumor growth as well as prolonged survival time of tumor bearing mice by increasing infiltration of CD8+ T cells as well as promoted the maturation of dendritic cells both in tumor and lymph. Together, LsiRNAs provide a simple but effective way for siRNA tumor delivery that “hitchhikes” on albumin.
Macrocyclic supramolecular complexes demonstrate the dynamic potential to solve global biomedical challenges, a promising cancer treatment modality. The macrocyclic system is an important heterocyclic system widely present in natural products and synthetic molecules. The unique structural feature of macrocyclic supramolecular complexes with desirable donor & acceptor characteristics is beneficial for readily binding with various enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. Macrocyclic-related research and macrocyclic moleculesbased medicinal chemistry developments have become rapidly developing areas of study. Numerous macrocyclic-based molecules as clinical drugs have been extensively used in the clinic to treat various diseases with high therapeutic potency. This critically analyzed work systematically reviews current developments of macrocyclic supramolecular complexes-based compounds in the range of medicinal chemistry as anticancer, anti-inflammatory, and other therapeutic agents, together with their potential applications in diagnostics and pathology. This review will be helpful for medicinal chemistry researchers to develop new thoughts in the quest for rational designs of more active and less toxic macrocyclic supramolecular complexes-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.
Condensed-phase synthesis of atomically precise clusters has become a vital branch of cluster science, where solvents are indispensable in the synthesis process. Herein, by employing the density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we demonstrated that polar solvents not only provide an important environment to stabilize clusters, but they can also dramatically alter the electronic property of cluster anions forming novel superhalogen anions. Such a regulation effect was first verified in small model gas-phase pure and doped gold cluster anions, which was further evidenced in a real experimentally synthesized Au18 nanocluster. Different solvation models reveal that the solvent field, which is a noninvasive methodology different from conventional electron-counting rules, can be considered as a novel external field to remarkably increase the electron-binding capability of cluster anions while maintaining their geometrical and electronic structures. Considering the indispensability and convenient availability of the solvents, present findings may boost the potential applications of superatoms in constructing super oxidizers in the condensed phase.
Finding more effective and safe non-viral vectors to transfer genes into cancer cells has become the key of immune gene therapy for cancer. Herein a triblock compound MPEG2000–PDLLA4000–MPEG2000 modified by cationic liposome DOTAP was used as a non-viral vector DOTAP/MPEG2000–PDLLA4000–MPEG2000 (DMPM) to effectively transfer interleukin (IL)-12 plasmid (pIL-12) into tumor tissue. IL-12 produced by transfected tumor cells successfully inducing lymphocyte proliferation and promoting interferon-γ (IFN-γ) secretion, which resulted in tumor cells death. The ability of DMPM to transfer pIL-12 and the immune effect induced by IL-12 in cells had been explored. The anti-tumor effect, mechanism and safety of pIL-12/DMPM in mice cancer model were investigated in this study. Our results showed that the pIL-12 transferred by DMPM was highly expressed both in CT26 cells and B16-F10 cells. IL-12 expressed in the culture supernatant of transfected tumor cells stimulated lymphocyte proliferation and promoted IFN-γ secretion. The experimental result confirmed that pIL-12/DMPM therapy significantly reduced tumor growth in mice model. We designed the nanocomposite DMPM to deliver pIL-12 for cancer treatment and explored its therapeutic efficacy and the underlying anti-tumor mechanism. Our study suggested pIL-12 loaded by DMPM complex would be an effective strategy for cancer treatment.
Flexible electronics technology is considered as a revolutionary technology to unlock the bottleneck of traditional rigid electronics that prevalent for decades, thereby fueling the next-generation electronics. In the past few decades, the research on flexible electronic devices based on organic materials has witnessed rapid development and substantial achievements, and inorganic semiconductors are also now beginning to shine in the field of flexible electronics. As validated by the latest research, some of the inorganic semiconductors, particularly those at low dimension, unexpectedly exhibited excellent mechanical flexibility on top of superior electrical properties. Herein, we bring together a comprehensive analysis on the recently burgeoning low-dimension inorganic semiconductor materials in flexible electronics, including one-dimensional (1D) inorganic semiconductor nanowires (NWs) and two-dimensional (2D) transition metal dichalcogenides (TMDs). The fundamental electrical properties, optical properties, mechanical properties and strain engineering of materials, and their performance in flexible device applications are discussed in detail. We also propose current challenges and predict future development directions including material synthesis and device fabrication and integration.