THz enantiomers of drugs recognized by the polarization enhancement of gold nanoparticles on an asymmetric metasurface.

Chirality plays an important role in biological processes, and enantiomers often possess similar physical properties and different physiological functions. Thus, chiral detection of enantiomers has become a hot topic in recent years, and methods to enhance chiral molecular recognition are in urgent demand. In this work, a polarization detection method was used for different chiral drugs based on a specially designed metasurface composed of asymmetric double-opened rings and the surface enhancement effect of gold nanoparticles (GNPs). The experiment results show that the frequency shifts caused by the nearfield interaction of the metasurface and biomolecules have been significantly improved by GNPs, and both the limit of detection and detection precision of the metasurface can reach the 10-5 g ml-1 level. Moreover, the polarization sensing characterized by right circular polarization (RCP), the polarization elliptical angle (PEA), and the polarization rotation angle (PRA) shows that the enantiomers of three drugs can be distinguished, especially using the PEA spectrum; the maximum difference between enantiomers is over 30° with a precision of 6.6 × 10-7 g mL-1. Our THz polarization sensing and the GNP enhancement method inspire an efficient strategy for the highly sensitive detection of enantiomers.

Terahertz phase shift sensing and identification of a chiral amino acid based on a protein-modified metasurface through the isoelectric point and peptide bonding.

The efficient sensing of amino acids, especially the distinction of their chiral enantiomers, is important for biological, chemical, and pharmaceutical research. In this work, a THz phase shift sensing method was performed for amino acid detection based on a polarization-dependent electromagnetically induced transparency (EIT) metasurface. More importantly, a method for binding the specific amino acids to the functional proteins modified on the metasurface was developed based on the isoelectric point theory so that the specific recognition for Arginine (Arg) was achieved among the four different amino acids. The results show that via high-Q phase shift, the detection precision for L-Arg is 2.5 × 10-5 g /ml, much higher than traditional sensing parameters. Due to the specific electrostatic adsorption by the functionalized metasurface to L-Arg, its detection sensitivity and precision are 22 times higher than the other amino acids. Furthermore, by comparing nonfunctionalized and functionalized metasurfaces, the D- and L-chiral enantiomers of Arg were distinguished due to their different binding abilities to the functionalized metasurface. Therefore, this EIT metasurface sensor and its specific binding method improve both detection precision and specificity in THz sensing for amino acids, and it will promote the development of THz highly sensitive detection of chiral enantiomers.

Terahertz circular polarization sensing for protein denaturation based on a twisted dual-layer metasurface.

Protein denaturation has very important research value in nutrition, biomedicine, and the food industry, which is caused by the changes in the molecular structure of the protein. Since the collective vibrational and torsional modes of protein molecules are within the terahertz (THz) frequency range, THz spectroscopy can characterize the protein denaturation with several advantages of non-contact, label-free, real-time, and non-destructive. Therefore, we proposed a reflective THz time-domain polarization spectroscopy sensing method, and use a flexible twisted dual-layer metasurface film as a sensor to realize the thermal denaturation sensing, concentration sensing, and types identification of protein aqueous solutions. The experiment tested three proteins (bovine serum albumin, whey protein, and ovalbumin), and the results show that: for the thermal denaturation sensing, its detection sensitivity can reach 6.30 dB/% and the detection accuracy is 0.77%; for the concentration sensing, the detection sensitivity and detection accuracy reach 52.9 dB·mL/g and 3.6·10-5 g/mL, respectively; in addition, different protein types can be distinguished by the difference of the circular polarization spectra.

The efficacy and safety of SGLT2 inhibitors combined with ACEI/ARBs in the treatment of type 2 diabetes mellitus: A meta-analysis of randomized controlled studies.

BACKGROUND: The efficacy and safety of the combination therapy with sodium-glucose cotransporter 2 (SGLT2) inhibitors and angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARBs) in the treatment of type 2 diabetes mellitus (T2DM) was not clear yet. RESEARCH DESIGN AND METHODS: A meta-analysis of randomized controlled studies (RCTs) was performed by searching in CENTRAL, Web of Science, PubMed, and Embase. RESULTS: Eight RCTs involving 6,386 participants were finally enrolled in this meta-analysis. Compared with placebo plus ACEI/ARBs, combined therapy with SGLT2 inhibitors and ACEI/ARBs induced a significant reduction in glycated hemoglobin (HbA1c) level by 0.43% (95% confidence interval [CI]: -0.55, -0.31), fasting plasma glucose level by 16.51 mg/dL (95% CI: -21.94, -11.08); systolic/diastolic blood pressure (BP) by 5.34 mmHg (95% CI: -7.47, -3.21)/1.27 mmHg (95% CI: -1.95, -0.59), respectively; and body weight (BW) by 1.45 kg (95% CI: -2.24, -0.65). Combined therapy was also found to be associated with a lower risk of adverse events. However, a higher risk of genital infections was observed with combination therapy than with placebo. CONCLUSIONS: This combination therapy showed satisfactory effects on lowering glycemic, BW, and BP in the treatment of T2DM patients. The safety of this combination therapy was also acceptable.