Ligand‐Functionalization of BPEI‐Coated YVO4:Bi3+,Eu3+ Nanophosphors for Tumor‐Cell‐Targeted Imaging Applications

In this study, surface‐functionalized, branched polyethylenimine (BPEI)‐modified YVO₄:Bi³⁺,Eu³⁺ nanocrystals (NCs) were successfully synthesized by a simple, rapid, solvent‐free hydrothermal method. The BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs with high crystallinity show broad‐band excitation in the λ=250 to 400 nm near‐ultraviolet (NUV) region and exhibit a sharp‐line emission band centered at λ=619 nm under excitation at λ=350 nm. The surface amino groups contributed by the capping agent, BPEI, not only improve the dispersibility and water/buffer stability of the BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs, but also provide a capability for specifically targeted biomolecule conjugation. Folic acid (FA) and epidermal growth factor (EGF) were further attached to the BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs and exhibited effective positioning of fluorescent NCs toward the targeted folate receptor overexpressed in HeLa cells or EGFR overexpressed in A431 cells with low cytotoxicity. These results demonstrate that the ligand‐functionalized, BPEI‐coated YVO₄:Bi³⁺, Eu³⁺ NCs show great potential as a new‐generation biological luminescent bioprobe for bioimaging applications. Moreover, the unique luminescence properties of BPEI‐coated YVO₄:Bi³⁺,Eu³⁺ NCs show potential to combine with a UVA photosensitizing drug to produce both detective and therapeutic effects for human skin cancer therapy.     

Sensitive detection of human breast cancer cells based on aptamer–cell–aptamer sandwich architecture

Breast cancer is one of the most critical threats to the health of women, and the development of new methods for early diagnosis is urgently required, so this paper reports a method to detect Michigan cancer foundation-7 (MCF-7) human breast cancer cells with considerable sensitivity and selectivity by using electrochemical technique. In this method, a mucin 1 (MUC1)-binding aptamer is adopted to recognize MCF-7 human breast cancer cells, while enzyme labeling is employed to produce amplified catalytic signals. The molecular recognition and the signal amplification are elaborately integrated by fabricating an aptamer–cell–aptamer sandwich architecture on an electrode surface, thus a biosensor for the detection of MCF-7 is fabricated based on the architecture. The detection range can be from 100 to 1 × 10⁷ cells, and the detection limit can be as low as 100 cells. The method is also cost-effective and conveniently operated, implying potential help for the development of early diagnosis of breast cancer.     

Battery-triggered ultrasensitive electrochemiluminescence detection on microfluidic paper-based immunodevice based on dual-signal amplification strategy

Dual-signal amplification strategy for ultrasensitive electrochemiluminescence (ECL) multiplexed immunoassay on microfluidic paper-based analytical devices (μ-PADs) was demonstrated. This dual-signal amplification technique was achieved by employing graphene oxide-chitosan/gold nanoparticles (GCA) immunosensing platform and [4,4′-(2,5-dimethoxy-1,4-phenylene)bis(ethyne-2,1-diyl) dibenzoic acid] (P-acid) functionalized nanoporous silver (P-acid/NPS) signal amplification label. For further low-cost and disposable applications, battery-triggered constant-potential ECL (+1.0 V for P-acid label (vs. Ag/AgCl auxiliary electrode)) was applied on this paper-based immunodevice with the aid of a home-made voltage-tunable power device, allowing the traditional electrochemical workstation to be abandoned. We found that two tumor markers could be sequentially detected in the linear ranges of 0.003–20 and 0.001–10 ng mL⁻¹ with the detection limits down to 1.0 and 0.8 pg mL⁻¹, respectively, by simply reversing the connection mode on two working electrodes. The results exhibited excellent precision and high sensitivity of such immunoassay, and it also demonstrated that this battery-triggered ECL paper-based immunodevice could provide a rapid, simple and simultaneous multiplex immunoassay with high throughput, low-cost and low detection limits for point-of-care testing.     

Vitrifolin A: A Norlabdane Diterpenoid from the Fruits of Vitex trifolia Linn. var. simplicifolia Cham

A new norlabdane diterpenoid, named vitrifolin A, was isolated from the fruits of Vitex trifolia Linn. var. simplicifolia Cham. Its structure was elucidated by mean of spectroscopic methods, including HRESIMS, IR, 1D and 2D NMR. The inhibitory effect of vitrifolin A on nitric oxide production in lipopolysaccarideactivated mouse macrophages was also evaluated.     

Fluorescence-based immunoassay for human chorionic gonadotropin based on polyfluorene-coated silica nanoparticles and polyaniline-coated Fe3O4 nanoparticles

We report on an ultrasensitive fluorescence immunoassay for human chorionic gonadotrophin antigen (hCG). It is based on the use of silica nanoparticles coated with a copolymer (prepared from a fluorene, a phenylenediamine, and divinylbenzene; PF@SiO₂) that acts as a fluorescent label for the secondary monoclonal antibody to β-hCG antigen. In parallel, Fe₃O₄ nanoparticles were coated with polyaniline, and these magnetic particles (Fe₃O₄@PANI) served as a solid support for the primary monoclonal antibody to β-hCG antigen. The PF@SiO₂ exhibited strong fluorescence and good dispersibility in water. A fluorescence sandwich immunoassay was developed that enables hCG concentrations to be determined in the 0.01–100 ng·mL^?1 concentration range, with a detection limit of 3 pg·mL^?1.

Oxidant Effect of H2O2 for the Syntheses of Quinoline Derivatives via One-Pot Reaction of Aniline and Aldehyde

A convenient one-pot method for the synthesis of substituted quinolines via the reaction of aniline and aldehyde in the presence of a Lewis acid (AlCl₃) and an oxidant (H₂O₂) has been developed. Hydrogen peroxide was found to promote the reaction by its function as a hydrogen hunter, hindering the formation of by-product N-alkylaniline. The effect of the oxidant on the yield and selectivity was studied. When the molar ratio of aniline, n-butyraldehyde, and H₂O₂ was 1:3:0.5 at 25 °C, the yield of 3-ethyl-2-propylquinoline was improved from 64% (reaction without H₂O₂) to 84% (with H₂O₂), and the quinoline selectivity was improved to almost 100%. Moreover, the reaction time was obviously reduced. The substituent effect was also investigated in this work.     

Extraction Separation of BSA in Aqueous Two-Phase Systems of Anionic and Cationic Surfactant Mixtures

Aqueous two-phase systems (ATPS) are formed in mixtures of sodium dodecylsulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), and sodium bromide (NaBr). Two different kinds of ATPS appear when CTAB and SDS surfactants are in excess, respectively. Such ATPS may provide a new, useful partitioning system for separation of bovine serum albumin (BSA). The partitioning of BSA was studied in these systems. The results show that the partitioning is affected by the electrical property, the hydrophobicity and the structure of liquid crystal (LC), which exists in the top phase of the ATPS. BSA is extracted into the top phase with higher distribution coefficient when LC and BSA are oppositely charged. The hydrophobicity of LC, which can be improved by increasing the length of alkyl group, enhances the distribution coefficient. The hydrophobicity of lamellar LC and hexagonal LC is stronger than that of cubic LC, which causes extractive capability of the former is higher than the latter.     

Total synthesis of (−)-Englerin A

A novel and efficient total synthesis of Englerin A is reported. The synthesis featured an intramolecular olefin metathesis ring closure reaction and a highly stereoselective oxygen bridge formation induced by an iodonium ion. This strategy can be used for the synthesis of natural products Englerin A and Englerin B and can provide flexibility in the preparation of various 9-substituted analogues of Englerin A for further structure–activity relationship studies.