Citation: Liu, X.; Xu, J.; Lou, Y.; Pan,
C.; Zhang, Y.; Wang, Z. Aptamer-
Based Fluorescence Detection and
Selective Disinfection of Salmonella
Typhimurium by Using Hollow
Carbon Nitride Nanosphere.
Biosensors 2022, 12, 228. https://
doi.org/10.3390/bios12040228
Received: 19 March 2022
Accepted: 7 April 2022
Published: 9 April 2022
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Article
Aptamer-Based Fluorescence Detection and Selective
Disinfection of Salmonella Typhimurium by Using Hollow
Carbon Nitride Nanosphere
Xinyi Liu
1,2,3,4
, Jing Xu
1,2,3,4,
*, Yang Lou
5
, Chengsi Pan
5
, Yin Zhang
6
and Zhouping Wang
1,2,3,4,6,7,
*
1
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China;
lwhyliuxinyi@163.com
2
School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
3
International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China
4
Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, Jiangnan University,
Wuxi 214122, China
5
School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China;
yang.lou@jiangnan.edu.cn (Y.L.); cspan@jiangnan.edu.cn (C.P.)
6
Key Laboratory of Meat Processing of Sichuan, Chengdu University, Chengdu 610106, China;
zhangyin@cdu.edu.cn
7
National Engineering Research Center for Functional Food, Jiangnan University, Wuxi 214122, China
* Correspondence: xujing823@jiangnan.edu.cn (J.X.); wangzp@jiangnan.edu.cn (Z.W.)
Abstract:
Hollow carbon nitride nanosphere (HCNS) was synthesized via the hard template method
to improve the fluorescence characteristics, drug delivery ability, and photocatalytic activity. Blue
fluorescent HCNS was utilized as a quenching agent and an internal reference to combine with
Cy5-labelled aptamer (Cy5-Apt), resulting in an off-on fluorescence aptasensing method for the
detection of Salmonella typhimurium (S. typhimurium). Under optimum conditions, this fluorescence
assay presented a linear range from 30 to 3
×
10
4
CFU mL
−1
with a detection limit of 13 CFU mL
−1
.
In addition, HCNS was also used as a drug carrier to load chloramphenicol (Cap) molecules. The
Cap-loading amount of HCNS could reach 550
µ
g mg
−1
within 24 h, whereas the corresponding
Cap-release amount is 302.5
µ
g mg
−1
under acidic and irradiation conditions. The integration of
photocatalyst with antibiotic could endow HCNS-Cap with better disinfection performance. The
bactericidal efficiency of HCNS-Cap (95.0%) against S. typhimurium within 12 h was better than
those of HCNS (85.1%) and Cap (72.9%). In addition, selective disinfection of S. typhimurium was
further realized by decorating aptamer. Within 4 h, almost all S. Typhimurium were inactivated by
HCNS-Cap-Apt, whereas only 13.3% and 48.2% of Staphylococcus aureus and Escherichia coli cells were
killed, respectively. Therefore, HCNS is a promising bio-platform for aptamer-based fluorescence
detection and selective disinfection of S. typhimurium.
Keywords:
hollow carbon nitride nanosphere; aptamer; Salmonella typhimurium; fluorescence detec-
tion; selective antibacterial
1. Introduction
Food products are susceptible to bacterial infections during processing, transportation,
and storage, especially Campylobacter, Salmonella, Listeria, Escherichia coli (E. coli) O157:H7,
Staphylococcus aureus (S. aureus), and Bacillus cereus [
1
]. Foodborne diseases caused by
pathogenic bacteria pose a serious threat to the health of people and the development of
the food industry [2]. Among these pathogens, Salmonella typhimurium (S. typhimurium) is
one of the most dangerous Gram-negative bacteria, which can infect a series of hosts and
cause a variety of diseases, including gastroenteritis and typhoid fever. As S. typhimurium
widely exists in eggs, milk, and raw chicken products, it has raised continued concern in
Biosensors 2022, 12, 228. https://doi.org/10.3390/bios12040228 https://www.mdpi.com/journal/biosensors
