Yanlin Liu

Dimethylacetamide (DMAc) is used as an electrolyte stabilizing additive for lithium ion battery. The effects of DMAc on the enhancements of electrolyte thermal stability and the solid electrolyte interphases (SEIs) on graphite anode and LiFePO4 cathode were investigated via a combination of electrochemical methods, nuclear magnetic resonance (NMR), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), as well as X-ray photoelectron spectroscopy (XPS). It was found that 1.0 M LiPF6 EC/DMC/DEC (1/1/1,weight ratio) electrolyte with 1% DMAc incorporation can be stable at 85 °C for over 6 months without precipitation and color change. In addition, the addition of 1% dimethylacetamide (DMAc) can significantly improve the cyclic performance of a LiFePO4/graphite cell at elevated temperature. These improved performances are ascribed to the enhancement of the thermal stability of the electrolyte and the modification of SEI components on graphite anode and LiFePO4 cathode. The explicit working mechanism of DMAc stabilizing LiPF6-based electrolyte is also discussed by the density functional theory (DFT) calculations.

The second near-infrared (NIR-II) window is a fundamental modality for deep-tissue in vivo imaging. However, it is challenging to synthesize NIR-II probes with high quantum yields (QYs), good biocompatibility, satisfactory pharmacokinetics, and tunable biological properties. Conventional long-wavelength probes, such as inorganic probes (which often contain heavy metal atoms in their scaffolds) and organic dyes (which contain large π-conjugated groups), exhibit poor biosafety, low QYs, and/or uncontrollable pharmacokinetic properties. Herein, we present a bioengineering strategy that can replace the conventional chemical synthesis methods for generating NIR-II contrast agents. We use a genetic engineering technique to obtain a series of albumin fragments and recombinant proteins containing one or multiple domains that form covalent bonds with chloro-containing cyanine dyes. These albumin variants protect the inserted dyes and remarkably enhance their brightness. The albumin variants can also be genetically edited to develop size-tunable complexes with precisely tailored pharmacokinetics. The proteins can also be conjugated to biofunctional molecules without impacting the complexed dyes. This combination of albumin mutants and clinically-used cyanine dyes can help widen the clinical application prospects of NIR-II fluorophores.