Quartz Crystal Microbalance Detection of Poly(ADP-ribose) Polymerase-1 Based on Gold Nanorods Signal Amplification

Electrochemical detection of poly(ADP-ribose) polymerase-1 with silver nanoparticles as signal labels by integrating the advantages of homogeneous reaction with surface-tethered detection

Poly(ADP-ribose)polymerase-1 (PARP1) could be activated by binding to nucleic acids with specific sequences, thus catalyzing the poly-ADP-ribosylation (PARylation) of target proteins including PARP1 itself. Most of the previously reported electrochemical methods for the determination of PARP1 were relied on the electrostatic interactions, which required the pre-immobilization of DNA on an electrode for the capture of PARP1. Herein, we reported an "immobilization-free" electrochemical strategy for the assays of PARP1 on the basic of avidin-biotin interaction. Once PARP1 was activated by binding with the specific double-stranded DNA (dsDNA) in a homogeneous solution, the biotinylated nicotinamide adenine dinucleotide (biotin-NAD+) was transferred onto PARP1, resulting in the formation of biotinylated PAR polymers. The resulting biotinylated PAR polymers were then captured by a neutravidin (NA)-modified electrode through avidin-biotin interactions. The rich biotin moieties in the PAR polymers allowed for the capture of NA-modified silver nanoparticles (NA-AgNPs) through the avidin-biotin interactions. The surface-tethered AgNPs produced a well-defined electrochemical signal due to the characteristic solid-state Ag/AgCl process. The "immobilization-free", electrostatic interaction-independent electrochemical biosensor exhibited low background current, high sensitivity, and good stability. It has achieved the determination of PARP1 with a detection limit down to 0.7 mU. The biosensor was further applied to determine the inhibition efficiency of potential inhibitors with a satisfactory result. This method shows promising potential applications in PARP1-related clinical diagnosis and drug discovery.

A label-free electrochemical biosensor for sensitive analysis of the PARP-1 activity

Early diagnosis of tumors is becoming increasingly important in modern healthcare. As studies have demonstrated, Poly(ADP)ribose polymerase-1 (PARP-1) is overexpressed in more aggressive tumors. Consequently, sensitive detection of PARP-1 activity holds significant practical importance in clinical diagnostics and biomedical research. Herein, an electrochemical biosensor for the sensitive monitoring of the PARP-1 activity have been proposed. The presence of target PARP-1 firstly triggers enzyme-initiated auto-PARylation and formed negatively charged polymer consisting of a few to 200 ADP-ribose units. Due to electrostatic adsorption, negatively charged PAR will bind with a large number of positively charged methylene blue (MB) electroactive molecules. By detecting the electrochemical signal of MB on the indium tin oxide (ITO) electrode, PARP-1 activity detection was achieved with a linear detection range of 0-1.0 U and a detection limit as low as 0.003 U. The proposed biosensor shows great prospects of clinical application.

Piezoelectric biosensors: shedding light on principles and applications

The three decades of experience with piezoelectric devices applied in the field of bioanalytical chemistry are shared. After introduction to principles and suitable measuring approaches, active and passive methods based on oscillators and impedance analysis, respectively, the focus is directed towards biosensing approaches. Immunosensing examples are provided, followed by other affinity sensing approaches based on hybridization of nucleic acids, aptamers, monitoring of enzyme activities, and detection of pathogenic microbes. The combination of piezosensors with cell lines and testing of drugs is highlighted, including mechanically active cells. The combination of piezosensors with other measuring techniques providing original hybrid devices is briefly discussed.

Construction of a Dendritic Nanoassembly-Based Fluorescent Biosensor for Electrostatic Interaction-Independent and Label-Free Measurement of Human Poly(ADP-ribose) Polymerase 1 in Lung Tissues

Poly(ADP-ribose) polymerase 1 (PARP-1) is responsible for catalyzing the creation of poly(ADP-ribose) polymer and involved in DNA replication and repair. Sensitive measurement of PARP-1 is critical for clinical diagnosis. However, the conventional electrostatic attraction-based PAPR-1 assays usually involve laborious procedures, poor sensitivity, and false positives. Herein, we demonstrate the construction of a dendritic nanoassembly-based fluorescent biosensor for electrostatic interaction-independent and label-free measurement of human PARP-1 in lung tumor tissues. When PARP-1 is present, the specific double-stranded DNA (dsDNA)-activated PARP-1 transfers the ADP-ribosyl group from nicotinamide adenine dinucleotide (NAD+)/biotinylated NAD+ to the PARP-1 itself, resulting in the formation of biotinylated dsDNA-PARP-1-PAR polymer bioconjugates that can be captured by magnetic beads. Upon the addition of TdT, APE1, and NH2-modified T-rich probe, the captured dsDNAs with dual 3'-OH termini initiate TdT-activated APE1-mediated hyperbranched amplification to produce abundant dendritic DNA nanoassemblies that can be stained by SYBR Green I to generate a high fluorescence signal. This biosensor is characterized by a template-free, electrostatic interaction-independent, high sensitivity, and label-free assay. It enables rapid (less than 3 h) measurement of PARP-1 with a limit of detection of 4.37 × 10-8 U/μL and accurate measurement of cellular PARP-1 activity with single-cell sensitivity. Moreover, it is capable of screening potential inhibitors and discriminating the PARP-1 level in normal person tissues and lung cancer patient tissues, with great potential in PARP-1-related clinical diagnosis and drug discovery.

Streptavidin-Conjugated DNA for the Boronate Affinity-Based Detection of Poly(ADP-Ribose) Polymerase-1 with Improved Sensitivity

This work reports the development of a fluorescence method for the detection of poly(ADP-ribose) polymerase-1 (PARP1), in which a phenylboronic acid-modified fluorescein isothiocyanate dye (FITC-PBA) was used to recognize the formed poly(ADP-ribose) (PAR) polymer. The detection system was designed by conjugating recombinant streptavidin (rSA) with PARP1-specific double-stranded DNA (dsDNA) through streptavidin-biotin interaction. Capture of PARP1 via rSA-biotin-dsDNA allowed for the poly-ADP-ribosylation (PARylation) of both rSA and PARP1 in a homogeneous solution. The resulting rSA-biotin-dsDNA/PAR conjugates were then captured and separated via the commercialized nitrilotriacetic acid-nickel ion-modified magnetic bead (MB-NTA-Ni) through the interaction between NTA-Ni on MB surface and oligohistidine (His₆) tag in rSA. The PAR polymer could capture the dye of FITC-PBA through the borate ester interaction between the boronic acid moiety in PBA and the cis-diol group in ribose, thus causing a decrease in fluorescence signal. The PARylation of streptavidin and the influence of steric hindrance on PARylation efficiency were confirmed using reasonable detection strategies. The method showed a wide linear range (0.01~20 U) and a low detection limit (0.01 U). This work should be valuable for the development of novel biosensors for the detection of poly(ADP-ribose) polymerases and diol-containing species.

Background-Quenched Aggregation-Induced Emission through Electrostatic Interactions for the Detection of Poly(ADP-ribose) Polymerase-1 Activity

Poly(ADP-ribose) polymerase-1 (PARP1) is a potential biomarker and therapeutic target for cancers that can catalyze the poly-ADP-ribosylation of nicotinamide adenine dinucleotide (NAD⁺) onto the acceptor proteins to form long poly(ADP-ribose) (PAR) polymers. Through integration with aggregation-induced emission (AIE), a background-quenched strategy for the detection of PARP1 activity was designed. In the absence of PARP1, the background signal caused by the electrostatic interactions between quencher-labeled PARP1-specitic DNA and tetraphenylethene-substituted pyridinium salt (TPE-Py, a positively charged AIE fluorogen) was low due to the fluorescence resonance energy transfer effect. After poly-ADP-ribosylation, the TPE-Py fluorogens were recruited by the negatively charged PAR polymers to form larger aggregates through electrostatic interactions, thus enhancing the emission. The detection limit of this method for PARP1 detection was found to be 0.006 U with a linear range of 0.01~2 U. The strategy was used to evaluate the inhibition efficiency of inhibitors and the activity of PARP1 in breast cancer cells with satisfactory results, thus showing great potential for clinical diagnostic and therapeutic monitoring.

Sensitive detection of PARP-1 activity by electrochemical impedance spectroscopy based on biomineralization

Poly(ADP)ribose polymerase-1 (PARP-1) has attracted much attention as a tumor marker in recent years. Based on the large negative charge and hyperbranched structure of PARP-1 amplified products (PAR), many detection methods have been established. Herein, we proposed a label-free electrochemical impedance detection method based on the large amount of phosphate groups (PO₄^3-) on the surface of PAR. Although EIS method has high sensitivity, it is not sensitive enough to discern PAR effectively. Therefore, biomineralization was incorporated to increase the resistance value (R_ct) distinctly because of the poor electrical conductivity of CaP. During biomineralization process, plentiful Ca²⁺ was captured by PO₄^3- of PAR through electrostatic interaction, resulting in an increasing R_ct of modified ITO electrode. In contrast, when PRAP-1 was absent, only a little Ca²⁺ was adsorbed on the phosphate backbone of the activating dsDNA. As a result, the biomineralization effect was slight and only a negligible R_ct change occurred. Experiment results showed that R_ct was associated closely with the activity of PARP-1. There was a linear correlation between them when the activity value was in the range of 0.005-1.0 U. The calculated detection limit was 0.003 U. Results of real samples detection and the recovery experiments were satisfactory, indicating the method has an excellent application prospect.

Detection of β-amyloid peptide aggregates by quartz crystal microbalance based on dual-aptamer assisted signal amplification

β-amyloid peptide (Aβ) aggregates are regarded as a typical neuropathology hallmark for the diagnosis of Alzheimer's disease (AD). Aβ₄₀ aggregates include soluble oligomers (Aβ₄₀O) and insoluble fibrils (Aβ₄₀F). Both of them can simultaneously bind to two different kinds of its aptamer (Apt1 and Apt2). As a mass-sensitive sensing platform, quartz crystal microbalance (QCM) converts changes in mass on the Au chip surface into frequency shift. Here, a dual-aptamer assisted Aβ₄₀ aggregates assay was developed. Taking Aβ₄₀O detection as an example, Apt2 was modified on the surface of Au chip by Au-S bond. Subsequently, the solution consisted of Aβ₄₀O and gold nanoparticles-Apt1 (AuNPs-Apt1) were injected into the QCM chamber. As a result, Aβ₄₀O was specifically recognized and captured by Apt2. AuNPs-Apt1 were also combined on the surface of the Au chip because Aβ₄₀O can simultaneously bind to Apt1. Then, a significant frequency shift occurred because of the large weight of AuNPs. Similarly, this procedure can be used to detect Aβ₄₀F. This QCM biosensor was able to detect Aβ₄₀O with a range of 0.2-10 pM with a detection limit of 0.11 pM, while the linear range for Aβ₄₀F was 0.1-10 pM with a detection limit of 0.02 pM. This QCM biosensor was simple and highly sensitive, which provided a new method for Aβ₄₀ aggregates detection.

An Array SPRi Biosensor for the Determination on PARP-1 in Blood Plasma

A biosensor was developed for the quantification of poly(ADP-ribose) polymerase-1 (PARP-1) in body fluids. An antibody specific for PARP-1 was placed on a chip with cysteamine (linker) and a gold layer. This biosensor has a linear response range (10-1000 pg∙mL^-1) under appropriate pH conditions and with an antibody ligand concentration of 5 ng∙mL^-1. Plasma samples were diluted with PBS buffer in appropriate quantities so that they fell within the linear range of the calibration curve. The biosensor exhibited suitable precision and accuracy, and good recovery (at levels from 95% to 105%). The method was validated by means of PARP-1 determinations in plasma samples from patients with endometriosis and a control group, using surface plasmon resonance imaging (SPRi) biosensors and an enzyme-linked immunosorbent assay (ELISA) test. The Spearman correlation coefficient was close to 1. PARP-1 may be a marker providing information about pathological changes in the body during endometriosis.

Methods of PARP-1 Determination and its Importance in Living Organisms

Abstract:

PARP-1 is one of the 18 PARP enzymes that are involved in important processes at the cellular level. The most important tasks of PARP-1 are to detect and repair DNA damage and to prevent processes of apoptosis. By finding and using new strategies for marking and detecting the activity of this protein, it is possible to identify more and more tasks in which it participates. In pathological states, PARP-1 activity increases significantly. Since the 1980s, scientists have been searching for and discussing substances that may inhibit PARP-1 activity and disrupt DNA damage response pathways. In this way, unwanted cells could be destroyed. The paper presents a short description of the methods used in the determination of PARP-1 by various research groups. A critical approach to each of them was also made by pointing to the advantages and disadvantages of the described analytical methods. The literature review contains information on methods useful for PARP-1 determination, such as SPR, QCM, CL and FL, DPV, SDS-PAGE with MS, MALDI MS, Western Blot, ELISA and ATR-FTIR spectroscopy. It also includes analysis of the results of research on inhibitors that may be effective in the diagnosis and treatment of cancer and other diseases.

Au Nanoparticle-Based Amplified DNA Detection on Poly-l-lysine Monolayer-Functionalized Electrodes

Affinity sensing of nucleic acids is among the most investigated areas in biosensing due to the growing importance of DNA diagnostics in healthcare research and clinical applications. Here, we report a simple electrochemical DNA detection layer, based on poly-l-lysine (PLL), in combination with gold nanoparticles (AuNPs) as a signal amplifier. The layer shows excellent reduction of non-specific binding and thereby high contrast between amplified and non-amplified signals with functionalized AuNPs; the relative change in current was 10-fold compared to the non-amplified signal. The present work may provide a general method for the detection of tumor markers based on electrochemical DNA sensing.

Dual Imaging of Poly(ADP-ribose) Polymerase-1 and Endogenous H2O2 for the Diagnosis of Cancer Cells Using Silver-Coated Gold Nanorods

The imaging of tumor-related multitarget molecules is of great significance to raise the diagnostic accuracy for malignant tumors. Poly(ADP-ribose) polymerase-1 (PARP-1) has emerged as a potential clinical biomarker for tumor diagnosis due to its specific overexpression in cancer cells. High levels of H₂O₂ in the tumor microenvironment play vital roles in driving cancer progression. Inspired by these achievements, we employed a silver-coated gold nanorod (Au@Ag NR) as a plasmonic probe for dual imaging of intracellular PARP-1 and H₂O₂ under a dark-field microscope (DFM). Au@Ag NR was used not only to distinguish tumor cells from normal cells but also to induce the apoptosis of cancer cells owing to the etching of Ag shell by H₂O₂, accompanied by the color change from green to orange. On the other hand, Au@Ag NRs modified with active double-stranded DNA (dsDNA) could be utilized to image PARP-1 in cancer cells and quantitatively detect PARP-1 in vitro by naked eyes or DFM. The reason is that PARP-1 polymerized nicotinamideadenine dinucleotide (NAD⁺) into large and hyperbranched poly(ADP-ribose) polymer (PAR) on the surface of Au@Ag NRs, preventing the Ag shell from being etched by H₂O₂. As the PARP-1 activity increased, a blue-shift of the adsorption peak occurred along with a color change from pale pink to green, which could be recognized by naked eyes. Under DFM, its scattering light varied obviously from red to green. The proposed dual-imaging strategy holds good prospects in cancer diagnosis.

Sensitive Dual-Mode Biosensors for CYFRA21-1 Assay Based on the Dual-Signaling Electrochemical Ratiometric Strategy and "On-Off-On" PEC Method

Herein, an electrochemical (EC)-photoelectrochemical (PEC) dual-mode biosensor was constructed for cytokeratin 19 fragment 21-1 (CYFRA21-1) assay based on the dual-signaling electrochemical ratiometric strategy and "on-off-on" PEC method. The indium tin oxide (ITO) electrode was modified by 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)@C₆₀ and gold nanoparticles (Au NPs), and the double-stranded DNA composed of thiol/methylene blue (MB)-labeled single-stranded DNA (ssDNA) (S0-MB) and antibody/ferrocene (Fc)-labeled ssDNA (Ab1-S1-Fc) was immobilized on the Au NPs/PTCDA@C₆₀/ITO electrode via the Au-S bond between Au NPs and thiol of S0-MB. With the help of another antibody-labeled ssDNA (Ab2-S2), the presence of CYFRA21-1 triggered a typical antigen-antibody sandwich immune reaction (Ab1, CYFRA21-1, and Ab2) and proximity hybridization between Ab1-S1-Fc and Ab2-S2. This caused the release of Ab1-S1-Fc from the modified electrode and the change of S0-MB to a hairpin structure, resulting in a decrease (an increase) of the oxidation peak current of Fc (MB) and an increase of the photocurrent due to the enhancing (inhibiting) effect of MB (Fc) on the photoelectric performance of the Au NPs/PTCDA@C₆₀/ITO electrode. Thus, CYFRA21-1 was detected by the developed EC-PEC dual-mode sensing platform sensitively, and the linear response ranges of 0.001-40 ng/mL with a detection limit of 0.3 pg/mL for the EC technique and 0.0001-4 ng/mL with a detection limit of 0.03 pg/mL for the PEC method were obtained. Furthermore, by changing the specific antibodies of disease-related biomarkers, the developed dual-mode biosensing platform could be readily extended to detect other antigens, implying its great potential applications in biological analysis and early disease diagnosis.

Age-related activity of Poly (ADP-Ribose) Polymerase (PARP) in men with localized prostate cancer

Mutations in DNA repair genes have been connected with familial prostate cancer and sensitivity to targeted drugs like PARP-inhibitors. Clinical use of this information is limited by the small fraction of prostate cancer risk gene carriers, variants of unknown pathogenicity and the focus on monogenic disease mechanisms. Functional assays capturing mono- and polygenic defects were shown to detect breast and ovarian cancer risk in blood-derived cells. Here, we comparatively analyzed lymphocytes from prostate cancer patients and controls applying a sensitive DNA double-strand break (DSB) repair assay and a flow cytometrybased assay measuring the activity of Poly(ADP-Ribose)-Polymerase, a target in treatment of metastatic prostate cancer. Contrary to breast and ovarian cancer patients, error-prone DNA double-strand break repair was not activated in prostate cancer patients. Yet, the activity of PARP discriminated between prostate cancer cases and controls. PARylation also correlated with the age of male probands, suggesting male-specific links between mutation-based and aging-associated DNA damage accumulation and PARP. Our work identifies prostate cancer-specific DNA repair phenotypes characterized by increased PARP activities and carboplatin-sensitivities, detected by functional testing of lymphocytes. This provides new insights for further investigation of PARP and carboplatin sensitivity as biomarkers in peripheral cells of men and prostate cancer patients.

A signal-on photoelectrochemical aptasensor for chloramphenicol assay based on 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays

Severe challenges are still remained for development of highly sensitive, selective and stable photoelectrochemical (PEC) sensing technology, albeit with its broad application for chloramphenicol (CAP) detection. Herein, a novel "signal-on" PEC aptasensor was fabricated based on a 3D self-supporting Z-scheme AgI/Ag/BiOI heterojunction arrays subtly integrated with in-situ formed biocatalytic precipitation (BCP) for highly sensitive and selective determination of CAP. Impressively, the HRP modified CAP aptamer (HRP-CAP aptamer) was released from the electrode by its strong affinity to the introduced CAP, and gradually terminated the BCP reaction, in turn recovering the photocurrent. By virtues of the 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays and BCP signal amplification strategy, the resultant PEC sensor exhibited a wide linear range of 2-250 nM with a limit of detection (LOD) as low as 0.226 nM (S/N = 3). This work opens a new avenue for design of PEC aptasensing strategy and exhibits the marvelous potential in bioanalysis of environmental samples.

Recent advances in acoustic wave biosensors for the detection of disease-related biomarkers: A review

In the past several decades, acoustic wave biosensors, as an emerging kind of biosensors, have been developed and widely used for the detection of mass, viscosity, conductivity and density. Varieties of applications have been explored such as medical diagnosis, drug screening, environmental monitoring, food analysis and biochemical assay. Among them, the detection of disease-related biomarkers based on acoustic sensors has aroused great research interest all over the world. In this review, the classification and characteristics of acoustic wave biosensors are briefly introduced. Then, some classical studies and recent advances in disease-related biomarker detection utilizing these biosensors are summarized and detailed, respectively. Here, the disease-related biomarkers mainly include antigens, small molecular proteins, cancer cells, viruses and VOCs. Finally, challenges and future trends of these typical acoustic wave biosensors are discussed. Compared with other reviews of acoustic wave sensors, this review highlights the great potential of typical acoustic wave biosensors for early disease screening and diagnosis compared with widely-used medical imaging. Moreover, they are integrated with other technologies for the design of multi-analyte, multi-parameter and intelligent devices, collecting more comprehensive information from biomarkers. This review provides a new perspective on the applications and optimization of acoustic wave biosensors to develop more reliable platforms for disease-related biomarker detection and disease diagnosis.

An impedance biosensor based on magnetic nanobead net and MnO2 nanoflowers for rapid and sensitive detection of foodborne bacteria

Screening of pathogenic bacteria in foods is an effective way to prevent foodborne diseases. In this study, an impedance biosensor was developed for rapid and sensitive detection of Salmonella typhimurium using multiple magnetic nanobead (MNB) nets in a ring channel for continuous-flow separation of target bacteria from 10 mL of sample, manganese dioxide nanoflowers (MnO2 NFs) for efficient amplification of biological signal, and an interdigitated microelectrode for sensitive measurement of impedance change. First, the MNBs modified with capture antibodies were vortically injected from outer periphery of this ring channel to form multiple ring MNB nets at specific locations with high gradient magnetic fields. Then, the bacterial sample was continuous-flow injected, resulting in specific capture of target bacteria onto the nets, and the MnO2 NFs modified with detection antibodies were injected to form MNB-bacteria-MnO2 NF complexes. After the complexes were washed with deionized water to remove excessive nanoflowers and residual ions, H2O2 with poor conductivity was injected to reduce MnO2 NFs to conductive Mn2+ at neutral medium, leading to impedance decrease. Finally, impedance change was measured using the microelectrode for quantitative determination of Salmonella. This biosensor was able to separate ~60% of Salmonella from 10 mL of bacterial sample and detect Salmonella with a linear range of 3.0 × 101 to 3.0 × 106 CFU/mL in 1.5 h with lower detection limit of 19 CFU/mL. This biosensor might be further improved with higher sensitivity using a larger volume (100 mL or more) for routine screening of foodborne bacteria without bacterial pre-culture.

A highly sensitive quartz crystal microbalance sensor modified with antifouling microgels for saliva glucose monitoring

Saliva glucose detection based on quartz crystal microbalance (QCM) technology has become an important research direction of non-invasive blood glucose monitoring. However, the performance of this label-free glucose sensor is heavily deteriorated by the large amount of protein contaminants in saliva. Here, we successfully achieved the direct detection of saliva glucose by endowing the microgels on the QCM chip with superior protein-resistive and glucose-sensitive properties. Specifically, the microgel networks provide plenty of boric acid binding sites to amplify the signals of targeted glucose. The amino acid layer wrapped around the microgel and crosslinking layer can effectively eliminate the impact of non-specific proteins in saliva. The designed QCM sensor has a good linearity in the glucose concentration range of 0-40 mg L^-1 in the pH range of 6.8-7.5, satisfying the physiological conditions of saliva glucose. Moreover, the sensor has excellent ability to tolerate proteins, enabling it to detect glucose in 50% human saliva. This result provides a new approach for non-invasive blood glucose monitoring based on QCM.

Single-Particle Assay of Poly(ADP-ribose) Polymerase-1 Activity with Dark-Field Optical Microscopy

Poly(ADP-ribose) polymerase-1 (PARP-1), over expression in vast majority of cancer cells, is a potential biomarker for clinical diagnosis. However, very limited detection methods have been developed so far, especially for in situ intracellular imaging. Here, we developed a spectral-resolved single-particle detection method for detection of PARP-1 in vitro and in situ intracellular imaging with dark-field microscopy (DFM). A gold nanoparticle (50 nm) modified with active DNA duplex (Au₅₀-dsDNA) was used as a scattering probe. Under the function of active dsDNA, PARP-1 catalyzed to synthesize the hyperbranched poly (ADP-ribose) polymer (PAR) by using nicotinamideadenine dinucleotide as substrates, forming Au₅₀-dsDNA@PAR. Then, negatively charged PAR adsorbed positively charged AuNPs (8 nm) to form Au₅₀-dsDNA@PAR@Au₈. As a result, a notable red shift occurred in localized surface plasmon resonance scattering spectra of Au₅₀, accompanying with obvious color change. Thus, PARP-1 has been detected with a linear range from 0.2 to 10 mU based on the scattering spectra change. The detection limit was 2 orders of magnitude lower than previously reported methods. Probes showed distinct different colors in cancer cells and normal cells, realizing in situ imaging of intracellular PARP-1 at a single-particle level. Compared with previously reported fluorescence imaging methods, the proposed strategy avoided sophisticated label procedures, which has great potential to be used for clinical diagnosis and PARP-1 inhibitor research.