Enhanced long-lasting luminescence nanorods for ultrasensitive detection of SARS-CoV-2 N protein

ARTICLES SCIENCE CHINA Materials mater.scichina.com link.springer.com Published online 12 November 2024 | https://doi.org/10.1007/s40843-024-3148-9 Enhanced long-lasting luminescence nanorods for ultrasensitive detection of SARS-CoV-2 N protein Yi Wei1,2, Menglin Song1,3, Lihua Li1, Yingjin Ma1, Xinyue Lao1, Yuan Liu1, Guogang Li2 and Jianhua Hao1* ABSTRACT Persistent luminescence nanomaterials can remain luminescence when the light source is turned off, which exhibits promise in biosensor and bioimaging fields since they have the ability to completely eradicate tissue autofluorescence. Although significant progress has been made in the persistent luminescence biosensing, there is still a dearth of long-afterglow detection platform with low limit of detection (LOD) and high sensitivity. Herein, Zn2GeO4:Mn, Cr persistently luminescent nanorods (PLNRs) with superior persistent luminescence and long afterglow time were developed. The addition of Cr3+ manifestly improves persistent luminescence intensity and afterglow duration through creating a deep defect trap. Then the biosensors were constructed by combining the Zn2GeO4:Mn,Cr PLNRs-antibody and Fe3O4 magnetic nanoparticles (MNPs)-antibody for nucleocapsid protein detection based on electrostatic attraction. The LOD value for nucleocapsid protein realizes as low as 39.82 ag/mL, which is much lower than the previously reported persistent luminescent-based biosensors. Accordingly, the low detection sensitivity is attributed to fluorescence resonance energy transfer. In addition, high specificity is also achieved. Therefore, the as-prepared Zn2GeO4:Mn,Cr persistently luminescent materials can act as the promising candidate in biosensors applications. This strategy provides effective guidance for the development of biosensing platforms with high sensitivity and specificity. Keywords: Zn2GeO4:Mn, Cr, persistent luminescence, biosensor, nucleocapsid protein, high sensitivity INTRODUCTION Biomedical diagnosis and treatment techniques play vitally important role in early diagnosis treatment and prediction, evaluation and healthcare fields [1–4]. Biosensors have been applied in the detections of cancer, virus, bacteria and so on [5– 8]. One of the underlying challenges of biosensors is the lack of effective point-of-care detection approaches. Thus, the rapidspeed and definitive detection approach is important for biosensor applications. The usual detection methods include computed tomography (CT), viral culture, reverse transcriptionpolymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) [9–12]. CT scan involves multiple X-ray scans of the patient’s body at different angles to pro- duce cross sectional images, which belongs to a non-invasive tool [13]. The disadvantage of CT for virus detection is the low specificity, detection sensitivity and accuracy [14,15]. RT-PCR is a standard technique for virus diagnostic, but it requires tedious sample pretreatment, highly trained operation staff, costly instruments and prolonged processing time [16,17]. ELISA is a rapid detection method that is established by a solid-phase enzyme immunoassay, but the relatively low sensitivity and the need for high-quality sample preparation limit its applications [18]. Hence, the development of new detection methods is a crucial issue in the further study. Fluorescence analysis technique has been considered as one of the most powerful approaches in biosensor applications [19,20]. Fluorescence probe is the indispensable component in fluorescence analysis technique. Commonly, fluorescence probes contain organic dyes, quantum dots, and up-conversion nanoparticles (UCNPs) [21–30]. Nevertheless, the above fluorescence probes cannot completely avoid the background fluorescence signals. Persistently luminescent material is known as “a legendary luminous pearl”, exhibiting bright luminescence for few seconds to several days when stopping excitation light sources. The persistent luminescence is mainly caused by the stored excitation energy in trap energy levels [31]. Persistent luminescence performance can efficiently achieve autofluorescence-free, leading to the improvement of detection accuracy in biosensor applications [32,33]. To date, some persistently luminescent materials have been reported with excellent persistent luminescence intensity and long-lasting persistent time, like green SrAl2O4: Eu2+, Dy3+ (>30 h), blue CaAl2O4:Eu2+, Nd3+ (>10 h), Near infrared (NIR)-emitting Zn3Ga2Ge2O10:Cr3+ (>10 h) and red Y2O2S:Eu3+, Mg2+, Ti4+ (>5 h) [34–37]. In order to achieve potential applications in biosensors, the particles size and shape of the persistently luminescent materials were further optimized by tuning the synthesis approaches. For instance, Zn2GeO4:Mn2+ (ZGO:Mn) persistently luminescent nanorods (PLNRs) were prepared with green emission based on hydrothermal method [38,39]. ZnGa2O4:Cr3+ nanospheres with NIR persistent luminescence were successfully obtained through hot injection methods [40,41]. Previously, the persistent nanomaterials were reported to achieve potential applications in disease biomarker detection, such as SARS-CoV-2 and bacteria [42–44]. Although significant progress has been made in particle size and shape of persistently luminescence materials, the persistent luminescence 1 Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong, China Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China 3 Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China * Corresponding author (email: ) 2 © The Author(s) 2024. This article is published with open access at link.springer.com. 1 ARTICLES SCIENCE CHINA Materials intensity and afterglow time still require further optimization. The underlying relationship between persistent luminescence and localized structure is unclear. Besides, the detection sensitivity of biosensor based on persistently luminescent materials should be further improved. In this manuscript, we design ions co-doping strategy by introducing Cr3+ in ZGO:Mn PLNRs, achieving improved persistent luminescence and longer afterglow time. The underlying luminescence enhancement mechanism is attributed to the introduction of deep defect trap. The biosensors was constructed by combining the Zn2GeO4:Mn,Cr PLNRs-antibody and Fe3O4 magnetic nanoparticles (MNPs)-antibody for nucleocapsid protein (N protein) detection based on electrostatic attraction, realizing low detection of limit (LOD) of 39.82 ag/mL. The proposed strategy can provide guidance for the development of highly sensitive and specific biosensor devices. EXPERIMENTAL SECTION Materials Zn(NO3)2·6H2O, Cr(NO3)3·9H2O, HNO3 (68%), and ammonium hydroxide (28%) were purchased from Sinopharm group. MnCl2·4H2O, GeO2, (3-aminopropyl)triethoxysilane (APTES), N,N-dimethylformamide (DMF), and 2-(N-morpholino) et (...truncated)