Latest ArticlesBased on 4-bromo-1, 8-naphthalic anhydride, one novel ratiometric fluorescence H2S-probe (IDNA) was designed and synthesized. Further studies indicate that IDNA can sensitively recognize H2S (detection limit of 7 μmol/L) with good selectivity and anti-interference ability. In addition, IDNA has satisfactory photostability in HeLa cells, ability of mitochondrial co-localization, and can be utilized in fluorescence imaging of H2S.
Recently, stimuli-responsive DNA nanostructure-based nanodevices have been applied for cancer therapy. In this study, pH-responsive i-motif DNA was modified on gold nanoparticles (AuNPs) via a facile, time-saving freeze-thaw method and utilized to construct stimuli-responsive drug nanocarriers. When the environment pH changes from 7.4 to 5.0, the i-motif DNA would be folded into four-stranded (C-quadruplex) that could be characterized by circular dichroism, and the characteristic of acid stimulate was verified by fluorescence resonance energy transfer (FRET). To enhance specifical cellular uptake, MUC1 aptamer was employed as the targeting moiety. Doxorubicin (Dox) is an anticancer drug that can be efficiently intercalated into GC base pairs of DNA nanostructure to form drug-loaded nanovehicles (Dox@AuNP-MUC1). Additionally, owing to the excellent photothermal conversion efficiency of AuNPs, the synergistic effect between chemotherapy and PTT can be readily achieved by 808 nm near-infrared (NIR) irradiation, which exhibits specifically and efficiently anticancer efficiency. Hence, this multifunctional drug carrier shows the potential for synergistic photothermal-chemotherapy.
A green tandem reaction, including insertion/aerobic oxidation/bisindolylation, starting from indoles and diazo compounds has been developed. The combination of water and fluorinated alcohol plays dual roles as solvent and promoter in this chemical transformation. Molecular oxygen in the air acts as an oxidant. 3, 3'-Bis(indolyl)methanes with quaternary carbon were produced under metal-free conditions. No any catalyst and additive were required. N2 and water were released as sole by-products. Absence of water and fluorinated alcohol resulted in Wolff rearrangement product.
Since the discovery of left-handed G-quadruplex (L-G4) structure formed by natural DNA, there has been a growing interest in its potential functions. This study utilised it to catalyse enantioselective Diels-Alder reactions, considering its different optical rotation compared to an ordinary G4. It was determined that when L-G4 was used with a combination of copper(Ⅱ) ions, there was a good enantioselectivity (-52% ee) without further addition of ligands. When further consideration was given by adding G4 ligands, G4 was further stabilised, even obtaining a better enantioselectivity (up to -80% ee). Moreover, when using ligands that have regulatory effects on G4, the ee value can be adjusted. In this work, a minimal left-handed G4 was reported. A follow-up study was also conducted, which recovers that the minimal left-handed G4 remains its catalytic effect and enantioselectivity, but is not so effective as the former case. This indicates that a complete G4 structure is relatively conducive to chiral catalysis.
Maximizing adsorption and catalytic active sites and promoting the photo-excited charge separation are two key factors to achieve excellent photocatalytic performance. In this study, we report a sol-gel synthesis approach to obtain non-metal doped TiO2 with sponge-like structure and surface-phase junctions all at once. While doping of carbon and nitrogen shifted the activation wavelength to the visible-light region, the innovative use of perchloric acid as a pore-making agent led to the formation of three-dimensional lamellar and porous structure with surface-phase junctions. High surface area with catalytic active sites rendered by the sponge-like structure and surface-phase junctions contributed to the much improved photocatalytic degradation efficiency toward rhodamine B, tetracycline and Disperse Red 60 with excellent reusability and stability. The improved generation and separation efficiency of the photo-induced charge carriers of the as-prepared TiO2 were supported by electrochemical impedance measurements and transient photocurrent responses. This method could also be applied to other photocatalysts to achieve structural alteration and element doping simultaneously.
In the past few years, photo-crosslinkable hydrogels have drawn a great attention in tissue engineering applications due to their high biocompatibility and extracellular matrix (ECM)-like structure. They can be easily biofabricated through exposure of a photosensitive system composed of photo-crosslinkable hydrogels, photo-initiators and other compounds such as cells and therapeutic molecules, to ultraviolet or visible light. With the development of biofabrication methods, many researchers studied the biological applications of photo-crosslinkable hydrogels in tissue engineering, such as vascular, wound dressing and bone engineering. This review highlights the biomaterials for photo-crosslinkable hydrogels, biofabrication techniques and their biological applications in tissue engineering. Meanwhile, the challenges and prospects of photo-crosslinkable hydrogels are discussed as well.
Understanding the physical mechanisms governing aggregation-induced-emission (AIE) and aggregation-caused-quenching plays a vital role in developing functional AIE materials. In this work, tetraphenylethene (TPE, a classical AIEgen) and naphthalimide (NI, a popular fluorophore with ACQ characteristics) were connected through non-conjugated linkages and conjugated linkages. We showed that the nonconjugated-linkage of TPE to NI fragments leads to substantial PET in molecular aggregates and ACQ. In contrast, the conjugated connection between TPE and NI moieties results in the AIE phenomenon by suppressing twisted intramolecular charge transfer. This work provides an important guideline for the rational design of AIE materials.
Quaternary ammonium salts (QASs) are excellent candidates for treating stubborn bacterial infections caused by biofilms due to their high sterilization efficiency and potential inhibition of the development of drug resistance. However, the inherent toxicity of QASs, including cytotoxicity, protein absorption and hemolysis, severely limits their applications in vivo. Herein, a charge-convertible quaternary ammonium salt-based micelle (QAS-SL@CM) was constructed by co-assembly of two amphiphiles with opposite charges and shell cross-linking strategy. The toxicity of the QAS-SL@CM could be greatly reduced towards human cells contrast to the corresponding QASs. By response to the acidic environment at infection sites, the surface charge of QAS-SL@CM could be immediately changed to positive and then target to negatively charged bacteria. Furthermore, β-thiopropionate bonds on QAS-SL@CM could also be disintegrated under acid environment to release QASs to kill bacteria. Importantly, the QAS-SL@CM showed significant therapeutic effect in mice subcutaneous abscesses models without interference with normal cells. Therefore, a surface adaptive micelle constructed by charge-convertible strategy has been developed to overcome the cytotoxicity of QASs, and could intelligently respond to the microenvironment of infected wound for in vivo infection therapy, which shows promising application in clinic.
An efficient approach to sulfur-bridged imidazopyridines has been developed under metal-free conditions using inexpensive sulfur powder as the sulfur source. Most appealingly, the reaction can proceed smoothly without addition of any additives, ultimately decreasing the production of chemical waste. The inexpensive and green method should provide a useful strategy for constructing a library of novel and biological interesting heteroaromatic sulfides.
The last few decades have witnessed the emergence of a very large variety of engineered nanomaterials. However, it is far from to meet the growing clinical demand. Actually, nature itself is an excellent nanotechnologist, and provides us with a range of wonderful materials, from inorganic particles found in non-life bodies to biofilms, like platelets, erythrocyte membranes, produced by many bacteria or cells. These nanomaterials are entirely natural, and not surprisingly, there is a growing interest in the development of natural nanoproducts. Native components-inspired biomaterials have gained considerable attention owing to their safety and functions. In this study, egg white was developed as drug carrier to load PTX by a green and simple one-pot method, and systematic characterization was completed. The results indicated that PTX@EW NPs possess excellent biocompatibility, enhanced tumor targeting capability, effectively reducing the toxic side effects of PTX. The obviously enhanced antitumor effect further confirmed EW was a highly prospective biomaterial in the nano-carrier industry.
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