Abstract-All-metal terahertz metamaterial biosensor for protein detection

 

Gangqi Wang, Fengjie Zhu, Tingting Lang, Jianjun Liu, Zhi Hong,  Jianyuan Qin 

https://nanoscalereslett.springeropen.com/articles/10.1186/s11671-021-03566-3

In this paper, a terahertz (THz) biosensor based on all-metal metamaterial is theoretically investigated and experimentally verified. This THz metamaterial biosensor uses stainless steel materials that are manufactured via laser-drilling technology. The simulation results show that the maximum refractive index sensitivity and the figure of merit of this metamaterial sensor are 294.95 GHz/RIU and 4.03, respectively. Then, bovine serum albumin was chosen as the detection substance to assess this biosensor’s effectiveness. The experiment results show that the detection sensitivity is 72.81 GHz/(ng/mm2) and the limit of detection is 0.035 mg/mL. This THz metamaterial biosensor is simple, cost-effective, easy to fabricate, and has great potential in various biosensing applications.

Abstract-Ultrasensitive detection of saccharides using terahertz sensor based on metallic nano-slits

Jianyuan Qin, 

Wei Cheng, 

Baojuan Han, 

Yong Du, 

Zhanghua Han & 

Zongshan Zhao 

Schematic diagram of sensing using metallic nano-slits. The inset shows the cross section of the metallic nano-slits, which are defined by the width d, thickness t, and periodicity p.

• 
  

https://www.nature.com/articles/s41598-020-60732-w#Ack1

Unambiguous identification of trace amounts of biochemical molecules in a complex background using terahertz spectroscopy is extremely challenging owing to the extremely small absorption cross sections of these molecules in the terahertz regime. Herein, we numerically propose a terahertz nonresonant nano-slits structure that serves as a powerful sensor. The structure exhibits strongly enhanced electric field in the slits (five orders of magnitude), as well as high transmittance over an extra-wide frequency range that covers the characteristic frequencies of most molecules. Fingerprint features of lactose and maltose are clearly detected using this slits structure, indicating that this structure can be used to identify different saccharides without changing its geometrical parameters. The absorption signal strengths of lactose and maltose with a thickness of 200 nm are strongly enhanced by factors of 52.5 and 33.4, respectively. This structure is very sensitive to thin thickness and is suitable for the detection of trace sample, and the lactose thickness can be predicted on the basis of absorption signal strength when the thickness is less than 250 nm. The detection of a mixture of lactose and maltose indicates that this structure can also achieve multi-sensing which is very difficult to realize by using the resonant structures.

Abstract-Structure and spectroscopic characterization of pharmaceutical co-crystal formation between acetazolamide and 4-hydroxybenzoic acid

Yaguo Wang, Jiadan Xue, Jianyuan Qin, Jianjun Liu, Yong Du

https://www.sciencedirect.com/science/article/pii/S138614251930469X

Co-crystals have great potential for drug research and development because the formation of co-crystal is accompanied by changes inter-molecular interactions between starting materials that enable to improve both physical and chemical properties of active pharmaceutical ingredients. In order to provide a more profound insight into the structural changes of specific drugs upon co-crystallization, spectroscopic characterization of solid-state acetazolamide (ACZ), 4-hydroxybenzoic acid (4HBA) and their co-crystal prepared by mechanical grinding approach has been performed with spectral techniques including terahertz time-domain spectroscopy (THz-TDS) and Raman spectroscopy. Experimental THz spectra show that the ACZ-4HBA co-crystal has a few significantly different absorption peaks in 0.82, 1.16, 1.28 and 1.64 THz respectively compared with parent materials in the frequency region from 0.2 to 1.8 THz. Likewise, such differences between the co-crystal and starting compounds could also be characterized by Raman vibrational spectra. Moreover, density functional theory (DFT) calculations were performed to simulate structures and vibrational modes of three kind of possible co-crystal theoretical forms (form I, II and III) between ACZ and 4HBA. Theoretical results and THz/Raman vibrational spectra of ACZ-4HBA co-crystal show that the 4HBA links to the thiadiazole acetamide fragment of ACZ via the double-bridged heterodimeric synthon C(N)NH⋯HOOC inter-molecular hydrogen bonding interaction establishing the theoretical form I, which is more consistent with experimental observations than other two co-crystal forms. These results provide rich information and unique method for characterizing the composition of co-crystal structures and also inter-molecular interactions shown within pharmaceutical co-crystallization process at the molecular level.

Abstract-Rapid qualitative and quantitative analysis of chlortetracycline hydrochloride and tetracycline hydrochloride in environmental samples based on terahertz frequency-domain spectroscopy

Yongmei Wang, Qiang Wang, Zongshan Zhao, Aifeng Liu, Yong Tiana, Jianyuan Qin,



https://www.sciencedirect.com/science/article/pii/S00399140183082

Owing to the advantages of transient, broadband, low-energy, transmission and high frequency accuracy, terahertz frequency domain spectroscopy (THz-FDS) has been introduced and pioneered for determining chlortetracycline hydrochloride (CCH) and tetracycline hydrochloride (TCH) in environmental samples, such as chicken, rice and soils. Their THz fingerprint spectra were located in the range of 0.4-1.1 THz, with the peaks at 0.49, 0.60, 0.76, 0.90 and 1.03 THz for CCH and at 0.52, 0.67, 0.79, 0.92 and 1.05 THz for TCH, respectively. By simple pressing treatment, dry soil, chicken and rice samples spiked with standards can be used for direct analysis. For the quantitative analysis, partial least squares regression (PLSR) algorithms were utilized for optimizing the analysis accuracy, calculation and prediction. Lower root mean square error of cross validation (RMSECV<0.1689), calibration (RMSEC<0.0623), prediction (RMSEP<0.1280) and higher correlation coefficient (R>0.9089) for these two compounds in soil, chicken and rice samples have been obtained. Our results indicated that THz-FDS combined with PLSR model could be a useful analytical technique for monitoring CCH and TCH in environmental samples.

Abstract-Enhanced terahertz sensing with a coupled comb-shaped spoof surface plasmon waveguide

Xiaomei Shi, Jianyuan Qin, and Zhanghua Han

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-1-278

A comb-shaped waveguide based on the excitation of coupled spoof surface plasmon (CSSP) mode is investigated, and is found to have a pronounced effect for the enhancement of fingerprint detection sensitivity in the terahertz (THz) regime. Composed of two oppositely oriented metal stripes with single-side comb-shaped corrugations, the waveguide is formed due to the coupling of SSP modes supported by metal corrugations on both sides and the mode is tightly localized between the central gap, which provides a perfect site for accommodating the samples in THz sensing. The effective detection of thin-layer lactose is given as an example to demonstrate the sensitive detection of it at a thickness of only a few microns. A transmission spectrum through the waveguide with a pronounced dip at its characteristic absorption frequency of 0.529THz is shown, which can never be observed using the transmission through a lactose layer with the same thickness.

© 2017 Optical Society of America

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Abstract-Discrimination of Transgenic Rice containing the Cry1Ab Protein using Terahertz Spectroscopy and Chemometrics

Wendao Xu,

Lijuan Xie,

Zunzhong Ye,

Weilu Gao,

Yang Yao,

Min Chen,

Jianyuan Qin

& Yibin Ying

• http://www.nature.com/srep/2015/150708/srep11115/full/srep11115.html

Spectroscopic techniques combined with chemometrics methods have proven to be effective tools for the discrimination of objects with similar properties. In this work, terahertz time-domain spectroscopy (THz-TDS) combined with discriminate analysis (DA) and principal component analysis (PCA) with derivative pretreatments was performed to differentiate transgenic rice (Hua Hui 1, containing the Cry1Ab protein) from its parent (Ming Hui 63). Both rice samples and the Cry1Ab protein were ground and pressed into pellets for terahertz (THz) measurements. The resulting time-domain spectra were transformed into frequency-domain spectra, and then, the transmittances of the rice and Cry1Ab protein were calculated. By applying the first derivative of the THz spectra in conjunction with the DA model, the discrimination of transgenic from non-transgenic rice was possible with accuracies up to 89.4% and 85.0% for the calibration set and validation set, respectively. The results indicated that THz spectroscopic techniques and chemometrics methods could be new feasible ways to differentiate transgenic rice.

Abstract-Feasibility of Terahertz Time-Domain Spectroscopy to Detect Tetracyclines Hydrochloride in Infant Milk Powder

Jianyuan Qin , Lijuan Xie , and Yibin Ying

Anal. Chem., Just Accepted Manuscript

DOI: 10.1021/ac503212q

Publication Date (Web): October 27, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/ac503212q

We report the use of terahertz time-domain spectroscopy (THz-TDS) to detect tetracyclines hydrochloride (TCsH) in infant milk powder for the first time. Four kinds of TCsH exhibited their unique spectral features in the region of 0.3-1.8 THz. The main spectral features of these TCsH were still detectable when mixed with infant milk powder with concentrations at 1%-50%, even in the ternary mixtures. The results from chemometrics analysis showed that qualitative and quantitative detection of TCsH in infant milk powder could be successfully achieved. The residual predictive deviation (RPD) values of all these TCsH models were all higher than 2, indicating these models were considered good, and could be used in screening purposes. The RPD values of TCH, DTCH and CTCH models were higher than 3, which were considered excellent for prediction purposes. These preliminary results indicated that THz-TDS combined with chemometrics analysis was suitable for detecting the presence of TCsH residues in a food matrix.