Encapsulation of Pure Water-Stable Perovskite Nanocrystals (PNCs) into Biological Environment-Stable PNCs for Cell Imaging.

Recently emerging perovskite nanocrystals (PNCs) are very attractive fluorescence nanomaterials due to their very narrow emission peak, tunable wavelength, and extremely high quantum yield, but their chemosensing, biosensing and bioimaging applications suffer from the poor stability of ordinary PNCs in aqueous media, especially in biological matrices. Recently developed water-stable 2D CsPb2Br5-encapsulated 3D CsPbBr3 PNCs (i.e., CsPbBr3/CsPb2Br5 PNCs) show extremely stable light emission in pure water, but their fluorescence is seriously quenched in aqueous media containing biological molecules due to their chemical reactions. In this work, we used a facile method to encapsulate pure water-stable CsPbBr3/CsPb2Br5 PNCs in water with SiO2 and polyethylene glycol hexadecyl ether (Brij58) into a new kind of biological environment-stable PNCs (CsPbBr3/CsPb2Br5@SiO2-Brij58). The synthesis of the target PNCs can be accomplished in a fast, easy, and green way. The obtained CsPbBr3/CsPb2Br5@SiO2-Brij58 PNCs maintain strong fluorescence emission for a long time, all in pH 7.4 PBS, BSA, and minimum essential medium, exhibiting excellent biological environment stability. Moreover, the developed biological environment-stable PNCs show good biocompatibility and have been successfully used in cell imaging. Overall, the work provides an easy, low-cost, and efficient application of PNCs in bioimaging.

Label-Free and Ultrasensitive Electrochemiluminescent Immunosensor Based on Novel Luminophores of Ce2Sn2O7 Nanocubes.

In this research article, a novel and simple label-free electrochemiluminescence (ECL) immunosensor using cerium stannite (Ce2Sn2O7) nanocubes as brand-new ECL emitters has been suggested for the first time. Ce2Sn2O7 nanocubes prepared by a simple hydrothermal method displayed bright ECL emission, promising biocompatibility, low noxiousness, and perfect stability. On comparison of ECL and photoluminescence (PL) spectra, a surface-state mechanism was proposed to be involved in the ECL emission. After aminofunctionalization with 3-aminopropyltriethoxysilane (APTES), Ce2Sn2O7 could be decorated with gold nanoparticles through Au-NH2 covalent linkage, which yielded Au@Ce2Sn2O7 nanocomposites and further enhanced the ECL emission. To confirm the proposed immunosensor feasibility, carcinoembryonic antigen (CEA) was employed as an exemplary analyte. Based on the abovementioned points, our fabricated immunosensor improved the ECL performance to CEA concentrations in a linear range of 0.001-70 ng/mL with a low limit of detection of 0.53 pg/mL (S/N = 3). With outstanding stability, reproducibility, and specificity, this method is expected to be an innovative one for sensitive analyses of CEA and other biomarkers in real samples.

Colorimetric immunosensor based on glassy carbon microspheres test strips for the detection of prostate-specific antigen.

Micro-sized glassy carbon microspheres (GCMs, typically 3 µm in diameter) instead of nano-sized gold nanoparticles (AuNPs, typically 20 nm in diameter) were for the first time used as signal markers for the quantitative detection of antigen such as prostate-specific antigen (PSA). After being treated with concentrated HNO3, GCMs bear carboxyl groups at their surfaces, which enables antibodies to be conjugated with GCMs to yield new type of micro-sized material-based colorimetric probes used for immunochromatographic test strips (ICTSs). The captured black GCMs (with strong and wide-band light absorption) on the T-line of ICTS were used both for qualitative and quantitative determination of PSA. In the case of quantitative determination, a lab-assembled optical strip reader system was used to measure the reflected LED light intensity at 550 nm. The sensing performances of the developed GCM-based ICTSs, such as sensitivity, selectivity, reproducibility, stability, and applicability, were investigated in detail. The developed GCM-based ICTSs can have much higher (3 times) detection sensitivity than AuNP-based ICTSs, showing promising applications in sensitive immunoassay.

Electrochemiluminescent immunosensor for prostate specific antigen based upon luminol functionalized platinum nanoparticles loaded on graphene.

A novel label-free electrochemiluminescent (ECL) immunosensor based upon luminol functionalized platinum nanoparticles loaded on graphene sheets (Lu-Pt@GS) as sensing platform was fabricated for highly sensitive and selective determination of prostate specific antigen (PSA). In this work, for the first time luminol was employed as both ECL luminescence reagent and reductants to in-situ reduce H2PtCl6 forming Pt NPs on surface of GS. A great deal of luminol could be attached onto the surface of Pt NPs within the reduction process, which can generate strong ECL emission. Pt NPs not only could enhance ECL signals of luminol but supply active sites for the immobilization of PSA antibodies with micro friendly environment. For preventing the consecutive reaction among luminol and H2O2, single-step cycle pulse was adopted, resulting in stable and strong ECL signals. Under optimized experimental conditions, the proposed ECL immunosensor acquired a wide linear range of 1 pg/mL to 10 ng/mL with a relatively low detection limit of 0.3 pg/mL for PSA. Furthermore, due to high sensitivity, simplicity and cost-effectiveness, the designed immunosensor provides a new method for detecting other important biomarkers in clinical analysis.

Aptamer based electrochemiluminescent thrombin assay using carbon dots anchored onto silver-decorated polydopamine nanospheres.

An electrochemiluminescent (ECL) aptamer based assay is described for thrombin. It is based on the use of carbon dots (C-dots) placed on polydopamine nanospheres loaded with silver nanoparticles (PDANS@Ag) and with probe DNA (pDNA). The PDANS possess high specific surface and can load a large number of C-dots. The AgNPs, in turn, enhance the ECL emission of the C-dots. Platinum functionalized graphene (Gr-Pt) can connect capture DNA (cDNA). The ECL nanoprobe consisting of PDANS@Ag/C-dots was placed on a glassy carbon electrode modified with Gr-Pt/cDNA/BSA via hybridization between cDNA and pDNA. On applying voltages from -1.8 V to 0 V, a strong ECL signal is generated. If thrombin is added, it will bind to cDNA. This leads to the release of pDNA from the electrode surface and a decrease in ECL intensity. Response to thrombin is linear in the 1.0 fmol·L-1 to 5.0 nmol·L-1 concentration range, with a 0.35 fmol·L-1 detection limit. The assay is stable, repeatable and selective, which demonstrates its clinical applicability. Graphical abstract Carbon dots (C-dots) placed on polydopamine nanospheres loaded with silver nanoparticles (PDANS@Ag) for electrochemiluminescent (ECL) detection of thrombin.

Qualitative and quantitative spectrometric evaluation of soluble microbial products formation in aerobic granular sludge system treating nitrate wastewater.

In present study, the characteristics of soluble microbial products (SMP) were evaluated in aerobic granular sludge system during denitrification process under different chemical oxygen demand/nitrogen (C/N) ratios. Batch experiment showed that the effluent nitrate (NO3--N) concentration were 15.24 ± 1.83 and 1.72 ± 1.53 mg/L at C/N ratio of 1 and 6, respectively. For the release of SMP, the protein (PN) and polysaccharide contents increased from 1.23 ± 0.38 and 7.46 ± 1.13 mg/L to 1.80 ± 0.76 and 10.53 ± 1.24 mg/L with increasing C/N ratios, respectively. Excitation-emission matrix identified four peaks in SMP, including aromatic PN-like, tryptophan PN-like, fulvic acid-like and humic acid-like substances. Fluorescence regional integration suggested that biodegradable PN-like substances occupied the percentage between 53.0 and 61.7% in SMP. Synchronous fluorescence spectra coupled with two-dimensional correlation spectroscopy indicated that the release of SMP fractions in the early stage (0-150 min) changed in the following sequences: PN-like fraction > fulvic acid-like fraction.

An ultrasensitive electrochemical immunosensor for the detection of prostate-specific antigen based on conductivity nanocomposite with halloysite nanotubes.

A sensitive label-free amperometric electrochemical immunosensor for detection of prostate-specific antigen (PSA) was proposed in this work. The nanocomposite of halloysite nanotubes with polypyrrole shell and palladium nanoparticles (HNTs@PPy-Pd) was used as a novel signal label. The HNTs with adequate hydroxyl groups are economically available raw materials. PPy, as an electrically conducting polymer material, can be absorbed to the surface of HNTs by in situ oxidative polymerization of the pyrrole monomer and form a shell on the HNTs. The shell of PPy could not only improve the conductivity of the nanocomposite but also absorb large amounts of Pd nanoparticles (NPs). The Pd NPs with high electrocatalytic activity toward the reduction of H2O2 and the HNTs@PPy-Pd nanocomposite as the analytical signal label could improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor showed a low detection limit (0.03 pg/mL) and a wide linear range (0.0001 to 25 ng/mL) of PSA. Moreover, its merits such as good selectivity, acceptable reproducibility, and stability indicate that the fabricated immunosensor has a promising application potential in clinical diagnosis. Graphical Abstract A new label-free amperometric electrochemical immunosensor based on HNTs@PPy-Pd nanocomposite for quantitative detection of PSA.

The synthesis of a BiOCl x Br1-x nanostructure photocatalyst with high surface area for the enhanced visible-light photocatalytic reduction of Cr(vi).

The photocatalytic reduction of poisonous Cr(vi) to environmentally friendly Cr(iii) driven by visible-light is highly foreseen. The construction of heterojunctions is a promising and solid strategy to tune the photocatalytic performance of BiOCl in the visible region. Herein, for the first time, we report Cr(vi) reduction by a BiOCl0.8Br0.2 composite produced via a facile in situ synthetic process at room temperature while making use of PVP (MW = 10 000). In this study, a series of BiOCl x Br1-x nanocomposites with different concentrations of chlorine and bromine have been prepared. The results show that BiOCl0.8Br0.2 has crystalline lattice, a large surface area (147 m2 g-1), a microporous structure (0.377 cm3 g-1), and very high chemical stability. It is revealed that the BiOCl0.8Br0.2 composite is much more active than those synthesized using different molar concentrations of chlorine and bromine. The DRS analysis and high photocurrent suggested that BiOCl0.8Br0.2 possessed absorption properties under visible light, which is beneficial for the efficient generation and separation of electron-hole pairs. In addition, we evaluated the photocatalytic activity of BiOCl0.8Br0.2 on the reduction of Cr(vi) under visible light irradiation and found that the obtained composite material exhibited a higher photocatalytic activity than single BiOCl or BiOBr without any decline in the activity after five cycles and is the best performing photocatalyst among those tested.

Recognition of M2 type tumor-associated macrophages with ultrasensitive and biocompatible photoelectrochemical cytosensor based on Ce doped SnO2/SnS2 nano heterostructure.

Tumor-associated macrophages (TAMs) play central roles in the regulation of tumor growth. TAMs can be differentiated into M1 and M2 types, which are responsible for the inhibition and growth of tumor tissues, respectively. Recognition of M2-TAMs is significant for the diagnosis and therapy of cancer, which is however severely limited due to the deficiency of selective and sensitive photoelectrochemical sensors. In this work, using Ce doped SnO2/SnS2 nano heterostructure as the highly sensitive platform, a photoelectrochemical sensor enabling the recognition of M2-TAMs was fabricated for the first time. By the decoration of CD163 antibody on the platform, the ultrasensitive photoelectrochemical sensor can selectively detect the CD163 protein on the surface of M2-TAMs. To our best knowledge, this is the first demonstration for recognition of M2-TAMs using photoelectrochemical method. The fabricated cytosensor has ultra-sensitive photocurrent response, applicable biological compatibility, high selectivity and relatively wide linear sensing range (5 × 101 to 1 × 105 cells/ml) with a low detection limit (50 cells/ml) for the detection of M2-TAMS. This kind of PEC cytosensor would provide a novel analysis and detection strategy for M2-TAMs.

Electrochemiluminescence behaviour of silver/ZnIn2S4/reduced graphene oxide composites quenched by Au@SiO2 nanoparticles for ultrasensitive insulin detection.

Herein, an effective electrochemiluminescence resonance energy transfer (ECL-RET) immunosensing strategy was proposed using silver/ZnIn2S4/reduced graphene oxide composites (Ag/ZnIn2S4/RGO) as the ECL donor and gold decorated silicon dioxide nanoparticles (Au@SiO2 NPs) as the ECL acceptor. ZnIn2S4 nanosheets (NSs), which exhibited strong ECL emission in the presence of potassium persulfate (K2S2O8) with ECL spectral band at 370-720 nm, were in situ grew on the RGO surface (ZnIn2S4/RGO) by a facile one-step hydrothermal method. Integrating with the morphological and electrical superiorities of RGO and AgNPs, the ECL emission of ZnIn2S4 at 551 nm was dramatically enhanced. Moreover, Au@SiO2 NPs whose UV-vis absorption spectra at 450-650 nm were firstly fabricated as a matched ECL acceptor for Ag/ZnIn2S4/RGO. Due to the fine spectral overlap between the ECL emission spectra of ZnIn2S4 NSs and the absorption spectra of Au@SiO2 NPs, efficient ECL quenching was induced for the sensitive responses and accurate quantification of insulin in real samples. Given the excellent linearity performed in 0.1 pg/mL - 80 ng/mL and the low detection limit achieved at 0.034 pg/mL (S/N = 3), the highly-efficient ECL-RET immunosensor holds splendid potential in detecting insulin and other biomarkers in human serum for the early diagnostics of serious diseases.

Electrochemiluminescence behaviour of silver/silver orthophosphate/graphene oxide quenched by Pd@Au core-shell nanoflowers for ultrasensitive detection of insulin.

Herein, a highly efficient electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was established for ultrasensitive insulin detection. Silver/silver orthophosphate/graphene oxide composites (Ag/Ag3PO4/GO) were prepared as sensing platform for capture-antibody (Ab1) incubation. Ag3PO4 is a novel ECL donor whose emission could be remarkably enhanced by the synergetic assistance of GO with Ag NPs. Notably, GO presented excellent electrical conductivity and ultrahigh specific surface area to improve the loading capacity Ab1 and Ag3PO4, and Ag NPs with fine biocompatibility and catalytic property could immobilize Ab1 via Ag-N bond and further hasten the electron transfer to catalyze the generation of SO4•- radicals for boosting the ECL emission of donor. To establish a new ECL-RET system, Pd@Au core-shell nanoflower was prepared as a suitable ECL acceptor which could immobilize the detection-antibody (Ab2). Due to the fine spectral overlap, Pd@Au nanoflower could significantly quench the ECL emission of Ag3PO4, causing distinct decreases in ECL intensity. The proposed ECL-RET immunosensor exhibited sensitive response to insulin in a linear range of 0.0001-80 ng/mL with a low detection limit of 0.02 pg/mL (S/N = 3), it not only provides a reliable tool for insulin detection in diagnostics of diabetes, but also lights up a new avenue for designing effective ECL-RET pairs in bioanalysis.

Label-free photoelectrochemical immunoassay for CEA detection based on CdS sensitized WO3@BiOI heterostructure nanocomposite.

In this work, a label-free photoelectrochemical (PEC) immunosensor for the detection of carcino embryonic antigen (CEA) was developed based on CdS nanowires (NWs) sensitized WO3@BiOI heterostructure. The construction procedure of ITO/WO3@BiOI@CdS electrode was done by dipping the WO3@BiOI modified indium-tin oxide (ITO) electrode interchangeably into [Cd(NH3)4]2+ and S2- solution for several times. Then the ITO/WO3@BiOI@CdS electrode was used as a matrix for the subsequent immobilization of CEA antibody (Ab). The obtained label-free PEC immunosensor showed an excellent PEC performance toward CEA detection. Under optimal conditions, the PEC immunosensor have a sensitive response to CEA in a liner range of 0.01ng/mL to 50ng/mL with a detection limit of 3.2pg/mL. The proposed PEC immunosensor exhibited good stability, high sensitivity as well as reproducibility and storage stability. Moreover, the obtained PEC immunosensor also showed a satisfied result in human serum sample analysis.

Dual-responsive electrochemical immunosensor for detection of insulin based on dual-functional zinc silicate spheres-palladium nanoparticles.

In this study, described an electrochemical immunoassay for insulin that is based on the use of zinc silicate spheres loaded with palladium nanoparticles (Zn2SiO4-PdNPs) that act as dual-function labels. The Zn2SiO4-PdNPs display high electrocatalytic activity towards the reduction of H2O2 and high sensitivity in chronoamperometry. The Zn2SiO4-PdNPs decrease the electron transfer rate between the electrolyte and the surface of the electrode, which can increase the changed current and enhance the sensitivity of the immunosensor as detected by square wave voltammetry (SWV). Electrodeposited gold is used as the matrix material. The icosahedral gold nanocrystals are coated with the primary antibodies formed a 3D mode to against abundant of insulin. Under optimal conditions, the assay has a linear response in the 0.1pgmL-1 to 50ngmL-1 insulin concentration range, and the limit of detection of the SWV and CA methods are 0.25 fg mL-1 and 80 fg mL-1, respectively. Moreover, the immunosensor holds an outstanding analytical performance for the insulin detection and has promising potential in clinical diagnosis.

A novel label-free photoelectrochemical sensor based on N,S-GQDs and CdS co-sensitized hierarchical Zn2SnO4 cube for detection of cardiac troponin I.

A novel label-free photoelectrochemical (PEC) sensor based on graphene quantum dots doped with nitrogen and sulfur (N,S-GQDs) and CdS co-sensitized hierarchical Zn2SnO4 cube was fabricated to detect cardiac troponin I (cTnI). The unique hierarchical Zn2SnO4 cube was synthesized successfully by the solvothermal method, which has a large specific surface to load functional materials. N,S-GQDs nanoparticles were assembled to the surface of cubic Zn2SnO4 coated ITO electrode, which efficiently accelerated the electronic transition and improved photo-to-current conversion efficiency. Then, CdS nanoparticles further were modified by in-situ growth method to form Zn2SnO4/N,S-GQDs/CdS composite with prominent photocurrent, which was 30 times that of the Zn2SnO4 cube alone. In this work, the specific immune recognition between cTnI antigens and cTnI antibodies (anti-cTnI) reduced the intensity of the photoelectric signal. And the intensity decreased linearly with the logarithm of cTnI concentration range from 0.001 ng/mL to 50 ng/mL with a detection limit of 0.3 pg/mL. With high sensitivity, excellent selectivity, good stability and reproducibility, the fabricated PEC sensor showed promising applications in the sensor, clinical diagnosis of myocardial infarction and PEC analysis.

Biosorption performance evaluation of heavy metal onto aerobic granular sludge-derived biochar in the presence of effluent organic matter via batch and fluorescence approaches.

In present study, the biosorption process of Cu(II) onto aerobic granular sludge-derived biochar was evaluated in the absence and presence of effluent organic matter (EfOM) by using batch and fluorescence approaches. It was found that EfOM gave rise to enhancement of Cu(II) removal efficiency onto biochar, and the sorption data were better fitted with pseudo-second order model and Freundlich equation, in despite of the absence and presence of EfOM. According to excitation-emission matrix (EEM), EfOM was mainly comprised by humic-like substances and fulvic-like substances and their intensities were reduced in the addition of biochar and Cu(II) from batch biosorption process. Synchronous fluorescence spectra coupled to two-dimensional correlation spectroscopy (2D-COS) further implied that a successive fluorescence quenching was observed in various EfOM fractions with the increasing Cu(II) concentration. Moreover, fulvic-like fraction was more susceptibility than other fractions for fluorescence quenching of EfOM.

Macroporous graphene capped Fe3O4 for amplified electrochemiluminescence immunosensing of carcinoembryonic antigen detection based on CeO2@TiO2.

A novel electrochemiluminescence (ECL) signal-amplified immunosensing strategy was proposed by using gold nanoparticles (Au NPs) functionalized reduced graphene oxide (rGO) capped Fe3O4 (Au-FrGO). In this work, CeO2@TiO2 was prepared by a sol-gel method to wrap CeO2 with TiO2. In the presence of CeO2, CeO2@TiO2 exhibited better ECL activity than TiO2 with peroxydisulfate as coreactant. In addition, FrGO with macroporous structure was synthesized by self-assembly of rGO sheets capped cationic Fe3O4 nanoparticles, exhibiting larger specific surface area than rGO. Due to the low toxicity and magnetism of Fe3O4, FrGO owned more favorable biocompatibility and the application of magnetic-separation simplified the preparation procedure. After hybridizing with Au NPs, FrGO exhibited more excellent electrical conductivity and could immobilize more CeO2@TiO2 and antibodies. Therefore, a novel label-free ECL immunosensor based on Au-FrGO-CeO2@TiO2 was constructed which generated higher ECL response. To investigate the performance of the immunosensor, carcinoembryonic antigen (CEA) was chosen as a model target analyte. Under optimal conditions, the immunosensor had sensitive response to CEA in a wide linear range of 0.01pgmL-1 to 10ngmL-1 with a detection limit of 3.28 fg mL-1. The proposed ECL immunosensor exhibited excellent stability, repeatability and selectivity, which opened another promising avenue for CEA determination in real serum samples.

An ultrasensitive photoelectrochemical immunosensor for insulin detection based on BiOBr/Ag2S composite by in-situ growth method with high visible-light activity.

A novel ultrasensitive label-free immunosensor based on BiOBr/Ag2S composite with high visible-light photoelectrochemical activity was prepared for the detection of insulin. After BiOBr was modified by thioglycolic acid, Ag2S nanoparticles were grown in-situ on the surface of BiOBr hierarchical microspheres to first form novel BiOBr/Ag2S composite. When ascorbic acid (AA) was used as an efficient electron donor for scavenging photo-generated holes, BiOBr/Ag2S composite material showed excellent photoelectrochemical activity. In order to immobilize insulin antibody, adhesive polydopamine (PDA) film formed by self-polymerization of dopamine was fabricated onto BiOBr/Ag2S modified electrode. Moreover, PDA film could further enhance the visible light absorption of BiOBr/Ag2S. When the solutions of 0.08molL-1AgNO3 and 0.1molL-1 AA were selected respectively during fabrication and detection process of this sensor, the best photocurrent singles were obtained. Under the optimum experimental condition, the specific binding between insulin and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of insulin concentration in the range of 0.001-20ngmL-1 with a detection limit of 0.2pgmL-1. The photoelectrochemical sensor ITO/BiOBr/Ag2S/PDA/anti-Insulin/BSA/Insulin revealed facile preparation, high sensitivity, and acceptable reproducibility, which may have practical applications in the biosensor, clinical diagnosis of cancers, photocatalysis, and other related fields.

Zinc-doping enhanced cadmium sulfide electrochemiluminescence behavior based on Au-Cu alloy nanocrystals quenching for insulin detection.

Novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated for insulin detection. Au-ZnCd14S combined nitrogen doping mesoporous carbons (Au-ZnCd14S/NH2-NMCs) acted as sensing platform and Au-Cu alloy nanocrystals were employed as labels to quench the ECL of Au-ZnCd14S/NH2-NMCs. Zinc-doping promoted the ECL behavior of CdS nanocrystals, with the best ECL emission obtained when the molar ratio of Zn/Cd was 1:14. Simultaneously, the modification of gold nanoparticles (Au NPs) and combination with NH2-NMC further enhanced the ECL emission of ZnCd14S due to its excellent conductivity and large specific surface area, which is desirable for the immunosensor construction. Au-Cu alloy nanocrystals were employed in the ECL system of ZnCd14S/K2S2O8 triggering ECL quenching effects. The ECL spectra of ZnCd14S, acting as the energy donor, exhibited well overlaps with the absorption band of Au-Cu alloy nanocrystals which acted as the energy acceptor, leading to an effective ECL resonance energy transfer (ECL-RET). On the basis of the ECL quenching effects, a sensitive ECL immunosensor for insulin detection was successfully constructed with a linear response range of insulin concentration from 0.1pg/mL to 30ng/mL and the limit of detection was calculated to be 0.03pg/mL (S/N = 3).

A bio-chemical application of N-GQDs and g-C3N4 QDs sensitized TiO2 nanopillars for the quantitative detection of pcDNA3-HBV.

Herein, TiO2 nanopillars (NPs)/N-doped graphene quantum dots (N-GQDs)/g-C3N4 QDs heterojunction efficiently suppressed the photogenerated charges recombination and improved photo-to-current conversion efficiency. The introduced N-GQDs and g-C3N4 QDs could result in more effective separation of the photogenerated charges, and thus produce a further increase of the photocurrent. TiO2 NPs/N-GQDs/g-C3N4 QDs were firstly applied as the photoactive materials for the fabrication of the biosensors, and the primers of pcDNA3-HBV were then adsorbed on the TiO2 NPs/N-GQDs/g-C3N4 QDs modified electrode under the activation of EDC/NHS. With increase of the pcDNA3-HBV concentration, the photocurrent reduced once the double helix between the primers and pcDNA3-HBV formed. The developed photoelectrochemical (PEC) biosensor showed a sensitive response to pcDNA3-HBV in a linear range of 0.01 fmol/L to 20nmol/L with a detection limit of 0.005 fmol/L under the optimal conditions. The biosensor exhibited high sensitivity, good selectivity, good stability and reproducibility.