Highly Specific,Single-step Cancer Cell Isolation with Multi-Aptamer-Mediated Proximity Ligation on Live Cell Membranes

A single-step method for isolation of specific cells based on multiple surface markers will have unique advantages because of its scalability, efficacy, and mildness. Herein, we developed multi-aptamer-mediated proximity ligation method on live cell membranes that leverages a multi-receptor co-recognition design for enhanced specificity, as well as a robust in situ signal amplification design for improved sensitivity of cell isolation. We demonstrated the promising efficacy of our method on differentiating tumor cell subtypes in both cell mixtures and clinical samples. Owing to its simple and fast operation with excellent cell isolation sensitivity and accuracy, this approach will have broad applications in biological science, biomedical engineering, and personalized medicine.     

Preparation of a novel bentonite intercalation composite by changing the chemical state of aluminum

A new environment-friendly bentonite intercalation composite was successfully obtained from alumina sol intercalation. This process used industrial grade pseudo boehmite as the aluminum source and provided with the advantage of zero emission of acidic wastewater. The bentonite intercalation composite was investigated by XRF, ICP, XRD, FT-IR, BET, and pyridine-FTIR. Results indicated that the basal spacing was enlarged from 14.72 to 15.60 Å; the specific surface area increased by 128%; and the total acid content increased from 65.32 to 245.76 μmol/g. The catalytic activity of this composite was tested by alkylation of aromatics with olefins. The results show that the weak Lewis acid generated by extra-framework aluminum and specific surface area play a decisive role, while weak Brønsted acid site is not the active site for this alkylation reaction.     

Sensitive and selective determination of 4-nitrophenol in water and food using modified polyethyleneimine-capped carbon dots

Hazardous 4-nitrophenol (4-NP) has created serious threats to humans and the environment; therefore, it is highly desirable to develop a facile and practical method for the monitoring of 4-NP in environment and food. Here, a fluorescence method based on modified polyethyleneimine-capped carbon dots (mPEI-CDs) was developed for sensitive and selective determination of 4-NP in water, fruit, and vegetable samples. First, highly fluorescent mPEI-CDs (quantum yield about 40.3%) were easily synthesized via a one-step hydrothermal method by using novel acetic anhydride modified polyethyleneimine (mPEI) and citric acid as precursors. Compared to the unmodified PEI-CDs, the acetic anhydride mPEI-CDs exhibited excellent fluorescent stability in a wider pH range of 4.0–9.0. Under pH 8.0, a selective determination of 4-NP was achieved based on the inner filter effect (IFE) mechanism. After optimization, good linear relationships between fluorescence intensity function (F₀-F)/F₀ and the concentration of 4-NP were obtained in ranges of 0.5–10 and 10–100 μM, respectively, while efficiently avoiding the interferences from two other nitrophenol isomers, possible coexisting metal cations and anions in samples. Finally, the proposed approach was successfully applied for the determination of 4-NP in water, honey, strawberry, and tomato samples.     

Recent developments of metallic nanoparticles and their catalytic activity in organic reactions

During the last two decades, with the development of nanotechnology, various nanomaterials have been designed and generated. Among them, hybrid organic–inorganic nanoparticles as a particular immobilizing carrier of the catalyst active sites have shown an important contribution in the current research studies. This is due to the large area and loads of active sites. This prominent review is focused on the novel various exa about the immobilization of nanoparticles with organic compounds as versatile and efficient catalysts in organic syntheses.     

Novel halogenated cyclopentasilylene-2,4-dienes via DFT

In view of immense importance of silylenes and the fact that their properties undergo significant changes on substitution with halogens, here, we have used B3LYP/6-311++G** level of theory to access the effects of 1–4 halogens (X = F, Cl, Br, and I) on four unprecedented sets of cyclopentasilylene-2,4-dienes; with the following formulas: SiC₄H₃X ( 1 _X ), SiC₄H₂X₂ ( 2 _X ), SiC₄HX₃ ( 3 _X ), and SiC₄X₄ ( 4 _X ). In going down from F to I, the singlet (s)-triplet (t) energy gap (ΔE_s-t, a possible indication of stability), and band gap (ΔE_H-L) decrease while nucleophilicity (N), chemical potential (μ), and proton affinity (PA) increase. The overall order of N, μ, and PA for each X is 2 _X > 1 _X > 3 _X > 4 _X . Precedence of 2 _X over 1 _X is attributed to the symmetric cross conjugation in the former. The highest and lowest N are shown by 2 _I and 4 _F . The trend of divalent angle () for each X is 4 _X > 1 _X > 3 _X > 2 _X . The results show that in going from electron withdrawing groups (EWGs) to electron donating groups (EDGs), the ΔE_s-t and ΔE_H-L decrease while N, μ, and PA increase. Also, rather high N of our scrutinized silylenes may suggest new promising ligands in organometallic chemistry.     

Phenazine Radical Cations as Efficient Homogeneous and Heterogeneous Catalysts for the Cross-Dehydrogenative Aza-Henry Reaction

The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo- and cross-coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross-dehydrogenative aza-Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross-linking of tetrakis(4-bromophenyl)silane and dihydrophenazine through Pd-catalyzed Buchwald-Hartwig cross-coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements.     

A DFT study on mechanisms of CO2 coupling with propargylic alcohols using alkali carbonates

The mechanisms of CO₂ coupling with the propargylic alcohol using alkali carbonates M₂CO₃ (M = Li, Na, K, Cs) have been investigated by means of density functional theory calculations. The calculations reveal that the target product tetronic acid (TA) is yielded through two stages: (a) the formation of the α-alkylidene cyclic carbonate (αACC) intermediate via Cs₂CO₃-mediated carboxylative cyclization of the propargylic alcohol with CO₂, and (b) the conversion of the αACC intermediate with Cs₂CO₃ to produce the cesium salt of the TA. Since the overall kinetic barriers for the two stages are comparable and affordable, the excellent chemoselectivity to the TA should be primarily originated from the high thermodynamic stability of the cesium salt of the TA. Moreover, relative to the TA, the possibility to yield the by-product acyclic carbonate can be excluded due to the both kinetics and thermodynamic inferiority. This result is different from the organic base-mediated reaction. Alternatively, our calculations predict that CsHCO₃ together generated with the cesium salt of the TA might also be an available mediating reagent for the incorporation of CO₂ with the propargylic alcohol. Compared to other alkali carbonates M₂CO₃ (M = Li, Na, K), the stronger basicity of Cs₂CO₃ and the lower ionic potential of cesium ion can raise the effective concentration of the αACC intermediate, and thus the conversion of the αACC intermediate into the cesium salt of the TA can be achieved with high yield.     

Accurate theoretical prediction of optical properties of BODIPY dyes

Boron-dipyrromethene dyes (BODIPY) are of great interest nowadays mostly due to their valuable optical properties. Nevertheless, no systematic research of the optical property dependence on the structure of dyes has been performed yet. In this work, analysis of the available quantum-chemical methods for BODIPY optical property calculations has been carried out. The accuracy of eight DFT functionals has been studied. The solvation effects upon excitation have been considered within two schemes. The methods that predict the absorption and emission spectra of BODIPY derivatives with high accuracy have been proposed. Using the suggested methods, the influence of nature of substituents and their position in the BODIPY core on the optical spectra of the dyes has been studied. A complex pattern of red- and blue-shifts in optical spectra in dependence of nature and position of substituents has been revealed. The results of this work provide the way for efficient design of BODIPY derivatives with desired optical properties.