Citation: Saleh, S.M.; El-Sayed, W.A.;
El-Manawaty, M.A.; Gassoumi, M.;
Ali, R. An Eco-Friendly Synthetic
Approach for Copper Nanoclusters
and Their Potential in Lead Ions
Sensing and Biological Applications.
Biosensors 2022, 12, 197. https://
doi.org/10.3390/bios12040197
Received: 26 February 2022
Accepted: 24 March 2022
Published: 26 March 2022
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Article
An Eco-Friendly Synthetic Approach for Copper Nanoclusters and
Their Potential in Lead Ions Sensing and Biological Applications
Sayed M. Saleh
1,2,
* , Wael A. El-Sayed
1,3
, May A. El-Manawaty
4
, Malek Gassoumi
5,6
and Reham Ali
1,7,
*
1
Department of Chemistry, College of Science, Qassim University, Buraidah 51452, Saudi Arabia;
w.shendy@qu.edu.sa
2
Chemistry Branch, Department of Science and Mathematics, Faculty of Petroleum and Mining Engineering,
Suez University, Suez 43721, Egypt
3
Photochemistry Department, National Research Centre, Dokki, Giza 12622, Egypt
4
Pharmacognosy Department, Pharmaceutical and Drug Industries Research Institute, National Research
Centre, 33 El Buhouth Street, Cairo 12622, Egypt; mayalyem@gmail.com
5
Department of Physics, College of Science, Qassim University, P.O. Box 64, Buraidah 51452, Saudi Arabia;
malek.gassoumi@gmail.com
6
Laboratory of Condensed Matter and Nanosciences, University of Monastir, Monastir 5000, Tunisia
7
Chemistry Department, Science College, Suez University, Suez 43518, Egypt
* Correspondence: e.saleh@qu.edu.sa (S.M.S.); re.ali@qu.edu.sa (R.A.)
Abstract:
A new preparation route for high-luminescent blue-emission pepsin copper nanoclusters
(Pep-CuNCs) is introduced in this work. The synthesized nanoclusters are based on a pepsin molecule,
which is a stomach enzyme that works to digest proteins that exist in undigested food. Here, we
have developed an eco-friendly technique through microwave-assisted fast synthesis. The resulting
copper nanoclusters (CuNCs) exhibit significant selectivity towards Pb(II) ions. The pepsin molecule
was utilized as a stabilizer and reducing agent in the production procedure of Pep-CuNCs. The
characteristics of the resulting Pep-CuNCs were studied in terms of size, surface modification, and
composition using various sophisticated techniques. The CuNCs responded to Pb(II) ions through the
fluorescence quenching mechanism of the CuNCs’ fluorescence. Thus, great selectivity of Pep-CuNCs
towards Pb(II) ions was observed, allowing sensitive determination of this metal ion at lab-scale and
in the environment. The CuNCs have detection limits for Pb(II) in very tenuous concentration at a
nanomalar scale (11.54 nM). The resulting Pep-CuNCs were utilized significantly to detect Pb(II) ions
in environmental samples. Additionally, the activity of Pep-CuNCs on different human tumor cell
lines was investigated. The data for the observed behavior indicate that the Pep-CuNCs displayed
their activity against cancer cells in a dose dependent manner against most utilized cancer cell lines.
Keywords:
copper nanoclusters; eco-friendly synthesis; pepsin; optical sensing; metal ions; anticancer
1. Introduction
With significant industrial progress in many fields, the need for the determination
of lead has increased. Lead ions are present and dispersed in varying amounts in nature,
as they are present in many ores such as galena, anglesite, and cerussite. Lead is used in
many industries, including for storage batteries, cable sheaths, weaponry, and radioactive
shielding. Lead is used in large quantities and added to gasoline to improve its properties.
Environmental lead pollution has caused many problems, and many countries have made
arrangements to reduce the use of lead in gasoline. However, lead in the environment
is recycled to be reused for valuable purposes. In general, lead compounds emitted into
the air typically end up in water sources [
1
]. Lead can destroy the nervous system and
cause kidney failure, and is recognized as a carcinogen [
2
]. Lead is generally found in the
environment in the form of inorganic lead(II) compounds. The Environment Protection
Agency (EPA) and World Health Organization (WHO) stated that acceptable concentrations
Biosensors 2022, 12, 197. https://doi.org/10.3390/bios12040197 https://www.mdpi.com/journal/biosensors
