Mixing Assisted "Hot Spots" Occupying SERS Strategy for Highly Sensitive In Situ Study.

To solve the problem that analyte molecules cannot easily enter "hot spots" on a conventional solid SERS substrate, we developed a mixing-assisted "hot spots" occupying (MAHSO) SERS strategy to improve utilization of "hot spots". Compared with the conventional substrate, the MAHSO substrate enhances the sensitivity of SERS measurement by thousands of times. The MAHSO substrate possesses excellent properties of high enhancement, high uniformity, and long-term stability because the MAHSO substrate is integrated inside an ultrafast microfluidic mixer. The mixer makes analytes and metal colloid homogeneously mixed, and analytes are naturally located in "hot spots", the gaps between adjacent NPs, during the process that NPs deposit on the channel wall. As a multi-inlet device, the MAHSO chip offers a convenient in situ method to study environmental effects on analytes or molecular interactions by flexibly regulating fluid in microchannels and monitoring responses of analytes by SERS spectra. Because all experiments are conducted in aqueous environments, which is similar to the physiological conditions, the MAHSO chip is especially suitable to be applied to study biomolecules. Using this strategy, different conformational changes of the wild type and mutant G150D of protein PMP22-TM4 depending on environmental pH have been observed in situ and analyzed. As a lab-on-a-chip (LoC) device, the MAHSO SERS chip will benefit the field of molecular dynamics, as well as molecule-molecule or molecule-surface interactions in the future.

Geographical identification of Chinese wine based on chemometrics combined with mineral elements, volatile components and untargeted metabonomics.

Identifying the geographic origin of a wine is of great importance, as origin fakery is commonplace in the wine industry. This study analyzed the mineral elements, volatile components, and metabolites in wine using inductively coupled plasma-mass spectrometry, headspace solid phase microextraction gas chromatography-mass spectrometry, and ultra-high-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry. The most critical variables (5 mineral elements, 13 volatile components, and 51 metabolites) for wine origin classification were selected via principal component analysis and orthogonal partial least squares discriminant analysis. Subsequently, three algorithms-K-nearest neighbors, support vector machine, and random forest -were used to model single and fused datasets for origin identification. These results indicated that fused datasets, based on feature variables (mineral elements, volatile components, and metabolites), achieved the best performance, with predictive rates of 100% for all three algorithms. This study demonstrates the effectiveness of a multi-source data fusion strategy for authenticity identification of Chinese wine.

Luminescent Perovskite-Cross-Linked Polymer with Low Shrinkage and Excellent Stability.

When organic cross-linked polymers are combined with metal halide perovskite nanocrystals (PNCs) for realizing luminescent perovskite-polymer display materials, the stability of PNCs is enhanced and their shrinkage is suppressed. This work presents a feasible strategy for preparing CsPbBr3 nanocrystals (NCs) within a polydicyclopentadiene (PDCPD) thermosetting cross-linked resin matrix simultaneously via a one-step reaction. The obtained PDCPD@PNCs composite exhibits narrow peak half-widths (15-20 nm), high light transmittance (80%), low curing volume shrinkage (1.4%), tunable tensile properties, excellent stability, and a photoluminescence quantum yield (PLQY) of 44.3%. The composite material exhibits long-term stability in water, acid, and base solutions for over 90 days, with the PL intensity being maintained at over 90%. Furthermore, the composite is highly resistant to polar organic solvents owing to the insolubility imparted by cross-linking. White LEDs (WLED) fabricated using the as-prepared composite demonstrate excellent potential as light sources in optical devices.

Synthesis and characterization of a julolidine-based electro-optic molecular glass.

AIM: Organic electro-optic (EO) materials have recently gained considerable attention owing to their advantages compared to inorganic EO materials. Among different kinds of organic EO materials, organic EO molecular glass exhibits desired prospect because of its high chromophore loading density and large macroscopic EO activity. INTRODUCTION: The objective of this study is to design and synthesize a novel organic EO molecular glass JMG utilizing julolidine moiety as the electron donor, thiophene moiety as the conjugated bridge, trifluoromethyl substituted tricyanofuran derivate (Ph-CF3-TCF) as the electron acceptor. METHOD: The JMG's structure was characterized through NMR and HRMS. The photophysical property, glass transition temperature, first hyperpolarizability (ß) and dipole moment (µ) of JMG were determined through UV-vis spectra, DSC test and DFT calculation. RESULTS: JMG's Tg reached to 79 °C and it can form high-quality optical film. The theoretical calculation shows that the first hyperpolarizability (ß) and dipole moment (µ) of JMG were calculated to 730×10-30 esu and 21.898 D. After connecting poling with the poling voltage of 49 V/µm at 90 ℃for 10 min, the highest EO coefficient (r33) of the poled JMG films reached to 147 pm/V. CONCLUSION: A novel julolidine-based NLO chromophore with two tert-butyldiphenylsilyl (TBDPS) groups was successfully prepared and characterized. TBDPS group is introduced as the film-forming group, and it also plays the role of isolation group, which can suppress the electrostatic interaction between chromophores, improve the poling efficiency and further enhance the EO activity. The excellent performances endow JMG with potential applications in device fabrication.

Thioaminal Covalent Adaptable Networks via Thiol-Aldehyde-Amine Multicomponent Polymerization.

Multicomponent polymerization (MCP) has the advantages of high efficiency, mild reaction conditions, and high yield and has been widely used to synthesize multifunctional polymers. In this report, we develop novel covalent adaptable networks (CANs) with dynamic thioaminal covalent bonds via a simple one-pot thiol-aldehyde-amine MCP. The dynamic behaviors of the thioaminal group are demonstrated. The obtained thioaminal CANs show the tensile strength of as high as 45 MPa via MCP of pentaerythritol tetra(3-mercaptopropionate), the mixture of formaldehyde and benzaldehyde, and 4,4'-methylenedianiline. Moreover, the CANs exhibit reprocessability, recyclability, and reconfigurable shape memory behaviors. Thus, the thiol-aldehyde-amine MCP represents a simple and efficient strategy for the preparation of versatile thioaminal CANs.