A sensitive biosensor based on a ferrocene-marked adapter for the fluorescence detection of platelet-derived growth factor BB
Graphical abstract
Scheme 1. Schematic of β-CD-CD fluorescent nanoprobe for PDGF-BB detection.
Introduction
Platelet-derived growth factor (PDGF)-BB is a well-known serum cytokine that regulates cell growth, division, and transformation [1,2]. PDGF-BB is a critical cancer-related protein marker in the human body with direct and indirect participation in cell proliferation, cell transformation, and tumor growth[3,4]. PDGF-BB is also a good predictor and indicator of early renal function deterioration, including diabetes, prostate cancer, and breast cancer[5,6]. Precise qualitative and quantitative detection of PDGF-BB can help in the early diagnosis and treatment of relevant diseases [7], as well as contribute to bioresearch and clinical diagnosis. Currently, various approaches such as enzyme-linked immunosorbent assay [8], antibody-based radioisotopes [9], molecular fluorescence technique [10], high-sensitivity electrochemical process [11], colorimetry [12], Raman method [13], and chemiluminescence immunoassay [14] are used to measure PDGF-BB. Despite the high sensitivity of these methods, they exhibit several limitations, such as high cost, instrumental complexity, and high requirement for operators. Thus, designing and creating convenient, sensitive, and selective biosensors with fast response and low cost are of great importance.
Carbon quantum dots (CDs) [15] are novel nanomaterials attracting extensive interest because of their advantages, such as high water solubility, low toxicity, high biological compatibility, light stability, abundant electron–hole exciton pairs, and functionality [16,17]. These CDs are favorable electron donors or receptors with strong ability of photoinduced electron transfer (PET)[18], synthesis and marked ability [19], and optical properties [20]. Moreover, CDs have wide-ranging applications, such as biological imaging [21], food safety [22], biomedicine[23], and chemical sensing. However, CDs from direct preparation usually have insufficient fluorescent quantum yield (FLQY < 50%) and sensitivity. For this reason, we doped N atoms containing quinquevalent electrons into the CDs[24,25], forming N-doped CDs to improve the FLQY[26]. β-Cyclodextrin (β-CD) is a ring-shaped oligonucleotide characterized by unique hydrophobic cavity, hydrophilic external structure, high water solubility [27], biocompatibility, and low toxicity [28]. The hydrophobic cavity of β-CD enables organic substances, inorganic materials, and biological molecules with appropriate sizes to be selectively coated through physical and chemical forces [29], thereby forming stable host–guest inclusion complexes, such as ferrocene[30] and adapters [31]. Accordingly, β-CD is attracting considerable attention, but its chemical inertia complicates the qualitative or quantitative analysis of substances that enter the cavity of β-CD. Nevertheless, β-CD functionalized CDs that integrate the properties of supramolecular compounds and nanometer properties of CDs can be prepared [30,32]. Molecular recognition and qualitative or quantitative detection can be achieved through PET or fluorescence resonance energy transfer of CDs.
Adapters are a type of functional nucleic acid macromolecules with specificity and affinity equivalent to antigen antibodies and can bind with various target substances, such as organic micromolecules [33], metal ions [34], proteins [35], and living cells [36]. Adapters with low cost, high stability, and high target-identification ability can be easily synthesized, marked, and modified in recent years; thus, they are extensively used in biomedicine, such as in biosensor development and nanoparticle-based drug delivery[37]. Ferrocene (Fc) is a common substance [38] that can penetrate the holes of β-CD-CDs through hydrophobic interaction, forming a stable 1:1 complex compound [39] and thus shortening the distance from the CDs of the probes [30]. When the distance between Fc and CDs is sufficiently close, under fluorescent irradiation, the excited electrons of CDs migrate to the empty orbit of Fc and do not return to the ground state, thereby inducing the PET and weakening the fluorescence of CDs [30,40]. When Fc is marked onto an adapter (e.g., single-stranded DNA (ssDNA)), the double properties of these substances can be obtained, including the specific molecular-recognition ability of the adapter and the electron signal transduction ability of Fc [41,42]. Both substances can interact with the holes of β-CD through host–guest identification, forming inclusions [31,39,43].
ssDNA and Fc can compete for host–guest in the cavity of β-CD, and ssDNA can block the PET between Fc and CDs. On the basis of this phenomenon and the double properties of ssDNA-Fc, we designed a novel fluorescent nano-bioaptamer sensor for the highly sensitive and rapid detection of PDGF-BB.
Section snippets
Materials and instruments
PDGF-BB was purchased from Cyagen Biosciences, Suzhou, China. PDGF-AA and PDGF-AB were purchased from Beijing Biolab Technology Co., Ltd. Mono(6-amino-6-deoxy)-β-CD was purchased from Shandong Binzhou Zhiyuan Biotechnology Co., Ltd. Anhydrous citric acid (CA), ethylenediamine, phosphate buffer solution (PBS; pH 7.4; containing 137 mM NaCl; 2.68 mM KCl, 8.1 mM Na2HPO4, and 1.76 mM KH2PO4), (ferrocenylmethyl)trimethylammonium iodide (Fc), and bovine serum albumin (BSA) were provided by Shanghai
Characterization
The β-CD-CD fluorescent nanoprobes were characterized by FTIR, UV–vis spectrum, TEM, and XPS.
The FTIR spectrum of β-CD-CDs exhibited three intense peaks at 1156, 1083, and 1031 cm−1 (Fig. 1A), which were characteristic of β-CD and caused by the coupling extensional vibration of C–O–H, C–C, and C–O and the asymmetric glucosidic bond vibration of C–O–C. The peak at 1717 cm−1 almost disappeared in CDs due to the stretching vibration of –COOH. However, two new peaks at 1684 and 1554 cm−1 appearing
Conclusions
Novel β-CD-CDs were synthesized starting from β-CD-functionalized environment-friendly N-doped CDs as fluorescent nanomaterials and used to measure PDGF-BB on the basis of the specific binding between the adapter and PDGF-BB and the photoelectron migration between cyclodextrin cavity and ferrocene. The PDGF-BB detection range widened according to the adapter-induced enhancement of fluorescence in β-CD-CDs, showing a linear range of 10 pg mL−1–8 μg mL−1 and a low detection limit of 6 pg mL−1
Declaration of competing interest
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed influencing the position presented in, or the review of, the manuscript entitled.
Acknowledgment
This work was financially supported by the Graduate Scientific Research Foundation of Shanxi Normal University (0109–01053002).
References (69)
- et al.
Diverse effects of platelet-derived growth factor-BB on cell signaling pathways
Cytokine
(2019) - et al.
Carbon-based nanocomposites with aptamer-templated silver nanoclusters for the highly sensitive and selective detection of platelet-derived growth factor
Biosens. Bioelectron.
(2017) - et al.
Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB
Biosens. Bioelectron.
(2016) - et al.
Portable aptamer biosensor of platelet-derived growth factor-BB using a personal glucose meter with triply amplified
Biosens. Bioelectron.
(2017) - et al.
Photoinduced electron transfer (PET) based label-free aptasensor for platelet-derived growth factor-BB and its logic gate application
Biosens. Bioelectron.
(2015) - et al.
AuNPs colorimetric sensor for detecting platelet-derived growth factor-BB based on isothermal target-triggering strand displacement amplification
Sens. Actuators B Chem.
(2015) - et al.
A novel electrochemiluminescent immunosensor based on the quenching effect of aminated graphene on nitrogen-doped carbon quantum dots
Anal. Chim. Acta
(2015) - et al.
Carbon dots: applications in bioimaging and theranostics
Int. J. Pharm.
(2019) A review on nanostructured carbon quantum dots and their applications in biotechnology, sensors, and chemiluminescence
Talanta
(2019)- et al.
Applications of carbon quantum dots (CQDs) in membrane technologies: a review
Water Res.
(2018)