Citation: Zafar, M.S.; Dastgeer, G.;
Kalam, A.; Al-Sehemi, A.G.; Imran,
M.; Kim, Y.H.; Chae, H. Precise and
Prompt Analyte Detection via
Ordered Orientation of Receptor in
WSe
2
-Based Field Effect Transistor.
Nanomaterials 2022, 12, 1305. https://
doi.org/10.3390/nano12081305
Academic Editors: Deepak Kukkar
and Ki-Hyun Kim
Received: 8 March 2022
Accepted: 7 April 2022
Published: 11 April 2022
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Article
Precise and Prompt Analyte Detection via Ordered Orientation
of Receptor in WSe
2
-Based Field Effect Transistor
Muhammad Shahzad Zafar
1,2
, Ghulam Dastgeer
3,
* , Abul Kalam
4,5
, Abdullah G. Al-Sehemi
4,5
,
Muhammad Imran
4,5
, Yong Ho Kim
2
and Heeyeop Chae
1
1
School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Korea;
mshahzad@skku.edu (M.S.Z.); hchae@skku.edu (H.C.)
2
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea;
yhkim94@skku.edu
3
Department of Physics and Astronomy, Graphene Research Institute-Texas Photonics Center International
Research Center (GRI–TPC IRC), Sejong University, Seoul 05006, Korea
4
Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004,
Abha 61413, Saudi Arabia; abul_k33@yahoo.com (A.K.); agmsq@kku.edu.sa (A.G.A.-S.);
imranchemist@gmail.com (M.I.)
5
Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004,
Abha 61514, Saudi Arabia
* Correspondence: gdastgeer@sejong.ac.kr; Tel.: +82-10-8343-1889
Abstract:
Field-effect transistors (FET) composed of transition metal dichalcogenide (TMDC) mate-
rials have gained huge importance as biosensors due to their added advantage of high sensitivity
and moderate bandgap. However, the true potential of these biosensors highly depends upon the
quality of TMDC material, as well as the orientation of receptors on their surfaces. The uncontrolled
orientation of receptors and screening issues due to crossing the Debye screening length while func-
tionalizing TMDC materials is a big challenge in this field. To address these issues, we introduce a
combination of high-quality monolayer WSe
2
with our designed Pyrene-based receptor moiety for its
ordered orientation onto the WSe
2
FET biosensor. A monolayer WSe
2
sheet is utilized to fabricate an
ideal FET for biosensing applications, which is characterized via Raman spectroscopy, atomic force
microscopy, and electrical prob station. Our construct can sensitively detect our target protein (strep-
tavidin) with 1 pM limit of detection within a short span of 2 min, through a one-step functionalizing
process. In addition to having this ultra-fast response and high sensitivity, our biosensor can be a
reliable platform for point-of-care-based diagnosis.
Keywords: tungsten di-selenide; gate-tunable; biosensor; orientation control; protein detection
1. Introduction
For a better health monitoring and curing system, the precise and prompt detection of
target analytes has gained importance. As in the COVID-19 situation, the rapid screening
of COVID-19 patients by sensitively detecting the spike protein can prevent the spread
of the virus [
1
,
2
]. Hence, there is high demand for a point-of-care (POC)-based health
monitoring system which can offer an ideal platform with low-cost, reliable, and easy-to-
use diagnostics of key biomarkers needed for the early screening of pandemics and other
health concerns. Most established methods for protein-based molecular diagnostic tests,
such as immunoassays, are time-consuming and costly to use, since they require many
reagents and skilled personnel. Due to this, their implementation as a POC-based system
has been limited and has become partially ineffective for service in a pandemic situation [
3
].
Hence, substrate-based detection systems are needed, as they provide the lab-on-a-chip
platform. However, the currently established substrate-based protein detection systems
are facing challenges regarding uncontrolled orientation, stabilization of target protein
with good surface density, and selectivity [
4
–
6
]. In short, a substrate based POC device
Nanomaterials 2022, 12, 1305. https://doi.org/10.3390/nano12081305 https://www.mdpi.com/journal/nanomaterials
