Integrating Near-Infrared Visual Fluorescence with a Photoelectrochemical Sensing System for Dual Readout Detection of Biomolecules

Red and near-infrared light-activated photoelectrochemical nanobiosensors for biomedical target detection

Photoelectrochemical (PEC) nanobiosensors integrate molecular (bio)recognition elements with semiconductor/plasmonic photoactive nanomaterials to produce measurable signals after light-induced reactions. Recent advancements in PEC nanobiosensors, using light-matter interactions, have significantly improved sensitivity, specificity, and signal-to-noise ratio in detecting (bio)analytes. Tunable nanomaterials activated by a wide spectral radiation window coupled to electrochemical transduction platforms have further improved detection by stabilizing and amplifying electrical signals. This work reviews PEC biosensors based on nanomaterials like metal oxides, carbon nitrides, quantum dots, and transition metal chalcogenides (TMCs), showing their superior optoelectronic properties and analytical performance for the detection of clinically relevant biomarkers. Furthermore, it highlights the innovative role of red light and NIR-activated PEC nanobiosensors in enhancing charge transfer processes, protecting them from biomolecule photodamage in vitro and in vivo applications. Overall, advances in PEC detection systems have the potential to revolutionize rapid and accurate measurements in clinical diagnostic applications. Their integration into miniaturized devices also supports the development of portable, easy-to-use diagnostic tools, facilitating point-of-care (POC) testing solutions and real-time monitoring.

DNA conformational change embrace ultraviolet photolysis: A dual-mode sensing platform for electrochemical and fluorescent signaling

We developed a dual-mode biosensor that utilizes DNA conformational changes and ultraviolet photolysis for electrochemical (EC) and fluorescence (FL) detection. In this study, a stem-loop-structured carcinoembryonic antigen (CEA) aptamer was modified on an Au electrode, and this aptamer contained a redox-labeled methylene blue (MB), short-chain DNA with a 6-carboxylic fluorescein (FAM) and a PC linker that can be cleaved by ultraviolet light. Subsequently, CEA and CEA antibody-modified upconversion nanoparticle bioconjugates (CEA-Ab@UCNPs) were added. In the presence of CEA, Ab@UCNPs can bind CEA and push the MB which was originally close to the electrode surface, away from the electrode surface, resulting in a reduced redox current. Under irradiation with a 980 nm laser, the UCNPs emit ultraviolet light, leading to photocleavage of the PC linker and the release of FAM for FL sensing. Under optimal conditions, the EC and FL modes showed good responses to CEA within 0.01-50 ng/mL and 0.1-80 ng/mL, respectively.

AI-Enhanced Visual-Spectral Synergy for Fast and Ultrasensitive Biodetection of Breast Cancer-Related miRNAs

In biomedical testing, artificial intelligence (AI)-enhanced analysis has gradually been applied to the diagnosis of certain diseases. This research employs AI algorithms to refine the precision of integrative detection, encompassing both visual results and fluorescence spectra from lateral flow assays (LFAs), which signal the presence of cancer-linked miRNAs. Specifically, the color shift of gold nanoparticles (GNPs) is paired with the red fluorescence from nitrogen vacancy color centers (NV-centers) in fluorescent nanodiamonds (FNDs) and is integrated into LFA strips. While GNPs amplify the fluorescence of FNDs, in turn, FNDs enhance the color intensity of GNPs. This reciprocal intensification of fluorescence and color can be synergistically augmented with AI algorithms, thereby improving the detection sensitivity for early diagnosis. Supported by the detection platform based on this strategy, the fastest detection results with a limit of detection (LOD) at the fM level and the R2 value of ∼0.9916 for miRNA can be obtained within 5 min. Meanwhile, by labeling the capture probes for miRNA-21 and miRNA-96 (both of which are early indicators of breast cancer) on separate T-lines, simultaneous detection of them can be achieved. The miRNA detection methods employed in this study may potentially be applied in the future for the early detection of breast cancer.

Constructed MXene matrix composites as sensing material and applications thereof: A review

Most studies on MXene matrix composites for sensor development have primarily focused on synthesis and application. Nevertheless, there is currently a lack of research on how the introduction of different materials affects the sensing properties of these composites. The rapid development of MXene has raised intriguing questions about improving sensor performance by combining MXene with other materials such as polymers, metals and inorganic non-metals. This review will concentrate on the construction of MXene-based composites and explore ways to enhance their sensor applications. Specifically, this review describes why the introduction of materials to the system brings the advantage of low concentration and high sensitivity assays, as well as the MXene-based frameworks that have been recently investigated. Lastly, in order to capture the current trend of MXene-based composites in sensor applications and identify promising research directions, this review will critically evaluate the potential applications of newly developed MXene systems.

Construction of Multi-Mode Photoelectrochemical Immunoassays for Accurate Detection of Cancer Markers: Assisted with MOF-Confined Plasmonic Nanozyme

In clinical diagnostics, sensitive and accurate biomarker monitoring is greatly challenged by the limitations of false positive/negative errors in single-modal photoelectrochemical analysis. Herein, we propose a multimode immunoassay by integrating photoelectrochemical, colorimetric, and photothermal imaging analysis into one electrode. The immunosensors could simultaneously achieve three detection modes at one electrode, which provided a new pathway for the accurate detection of the target prostate-specific antigen (PSA) and circumvented false-positive or negative errors during the detection process. To this end, an integrated multifunctional chip (TiO2/ZIF-8/Cu(II)) was first constructed via in situ embedding of Cu(II) in the Metal-organic framework growth process. Then, an alkaline phosphatase-labeled magnetic probe was designed to achieve split-type detection for PSA. In a sodium thiophosphate solution, the in situ generated H2S could react with Cu(II) to form small-size CuS due to the nanoconfinement of ZIF-8 and thus result in the formation of p-n heterojunctions (TiO2/ZIF-8/CuS). The TiO2/ZIF-8/CuS could efficiently improve the light-harvesting ability and facilitate the charge separation efficiency, thus finally resulting in an increased photocurrent in the PEC mode. Furthermore, by constructing the portable colorimetric and photothermal sensors based on the Arduino microcontroller and photothermal imager, the TiO2/ZIF-8/CuS also provided point-of-care and visual detection modes, as the in situ-formed CuS exhibited peroxidase-mimicking activity and outstanding photothermal properties. The work had important prospects for establishing multimode immunoassays for the accurate detection of cancer markers in early disease diagnosis.

Pyroelectric-Effect-Assisted Near-Infrared-Driven Photoelectrochemical Biosensor Based on Exponential DNA Amplifier for MicroRNA Detection

Although near-infrared responsive photoelectrochemical (PEC) biosensors have less damage to biological components compared to UV-visible light, they still reveal an inferior response due to the rapid recombination of photogenerated electron-hole. In this study, a near-infrared-driven PEC biosensor is fabricated for microRNA (miRNA) detection via integrating photoelectricity and pyroelectricity. Upon the introduction of target miRNA-21, the exponential DNA amplifier is triggered based on enzyme-assisted strand displacement amplification (SDA), releasing multiple Ag2S reporter probes to hybridize with capture probes immobilized on a CdS-2-mercaptobenzimidazole (2MBI)-modified photoelectrode. As a result, under the stimulation of NIR, the photoelectric conversion of Ag2S NPs generates the photocurrents. In addition, due to the strong hole acceptor ability of MBI, the pyroelectric effect of CdS-2MBI nanocomposites is enhanced, which generates highly pyroelectro-induced charge separation efficiency and induces the pyroelectric current benefited from the spontaneous polarization of CdS-2MBI caused by the temperature variation under the function of Ag2S nanoheaters. Impressively, this PEC biosensor has achieved the sensitive and selective determination of miRNA-21 with a detection limit as low as 54 fM. Overall, this NIR-driven PEC biosensor based on pyroelectric and photoelectric effects opens up a new horizon for bioanalysis and early disease diagnosis.

Ultrasensitive photoelectrochemical biosensor amplified by target induced assembly of cruciform DNA nanostructure for the detection of dibutyl phthalate

In this work, an ultra-sensitive signal quenched photoelectrochemical (PEC) aptasensor for dibutyl phthalate (DBP) detection was constructed by using a target induced cruciform DNA structure as signal amplifier and g-C₃N₄/SnO₂ composite as signal indicator. Impressively, the designed cruciform DNA structure shows high signal amplification efficiency due to the reduced reaction steric hindrance because of its mutually separated and repelled tails, multiple recognition domains, and a fixed direction for the sequential identification of the target. Therefore, the fabricated PEC biosensor demonstrated a low detection limit of 0.3 fM for DBP in a wide linear range of 1 fM to 1 nM. This work offered a novel nucleic acid signal amplification approach for enhancing the sensitivity of PEC sensing platforms for the detection of phthalates (PAEs)-based plasticizer, laying the foundation for its utilization in the determine of real environmental pollutants.

Dual-mode biosensor platform based on synergistic effects of dual-functional hybrid nanomaterials

Detection of biomarkers is very vital in the prevention, diagnosis and treatment of diseases. However, due to the poor accuracy and sensitivity of the constructed biosensors, we are now facing great challenges. In addressing these problems, nanohybrid-based dual mode biosensors including optical-optical, optical-electrochemical and electrochemical-electrochemical have been developed to detect various biomarkers. Integrating the merits of nanomaterials with abundant active sites, synergy and excellent physicochemical properties, many bi-functional nanohybrids have been reasonable designed and controllable preparation, which applied to the construction dual mode biosensors. Despite the significant progress, further efforts are still needed to develop dual mode biosensors and ensure their practical application by using portable digital devices. Therefore, the present review summarizes an in-depth evaluation of the bi-functional nanohybrids assisted dual mode biosensing platform of biomarkers. We are hoping this review could inspire further concepts in developing novel dual mode biosensors for possible detection application.

Signal Amplification-Based Biosensors and Application in RNA Tumor Markers

Tumor markers are important substances for assessing cancer development. In recent years, RNA tumor markers have attracted significant attention, and studies have shown that their abnormal expression of post-transcriptional regulatory genes is associated with tumor progression. Therefore, RNA tumor markers are considered as potential targets in clinical diagnosis and prognosis. Many studies show that biosensors have good application prospects in the field of medical diagnosis. The application of biosensors in RNA tumor markers is developing rapidly. These sensors have the advantages of high sensitivity, excellent selectivity, and convenience. However, the detection abundance of RNA tumor markers is low. In order to improve the detection sensitivity, researchers have developed a variety of signal amplification strategies to enhance the detection signal. In this review, after a brief introduction of the sensing principles and designs of different biosensing platforms, we will summarize the latest research progress of electrochemical, photoelectrochemical, and fluorescent biosensors based on signal amplification strategies for detecting RNA tumor markers. This review provides a high sensitivity and good selectivity sensing platform for early-stage cancer research. It provides a new idea for the development of accurate, sensitive, and convenient biological analysis in the future, which can be used for the early diagnosis and monitoring of cancer and contribute to the reduction in the mortality rate.

Dual Direct Z-Scheme Heterojunction with Stable Electron Supply to a Au/PANI Photocathode for Ultrasensitive Photoelectrochemical and Electrochromic Visualization Detection of Ofloxacin in a Microfluidic Sensing Platform

A novel dual-mode microfluidic analytical device integrating self-powered photoelectrochemical (PEC) sensing with electrochromic visualization analysis was developed for ultrasensitive ofloxacin (OFL) detection. First, an advanced dual direct Z-scheme BiVO₄@Ni-ZnIn₂S₄/Bi₂S₃ (BVZIS) heterojunction was designed as a photoanode matrix to steadily provide electrons. The dual Z-scheme structure formed in photoactive BVZIS composites greatly accelerated the migration of electrons. In addition, the doping of Ni in ZnIn₂S₄ markedly enhanced the optical absorption and promoted the separation of the photocarrier. Second, electrochromic material polyaniline-modified Au (Au/PANI) was first electrodeposited on the photocathode for immobilizing aptamers and realizing visualized readout. On the one hand, Au/PANI with excellent conductivity could receive electrons from the photoanode without external energy supply. On the other hand, PANI would be rapidly reduced by the received electrons and change its color from blue to green obviously. With the increase in OFL, the increased steric hindrance resulted in the significant decline in the PEC signal and RGBgreen value. Third, wide linear ranges of PEC (0.05 pg/mL to 150 ng/mL) and electrochromic technique (0.1 pg/mL to 100 ng/mL) as well as low detection limits of PEC (18 fg/mL) and electrochromic (30 fg/mL) sensors could achieve the ultrasensitive detection of OFL in milk and river water.

Photoelectrochemical and visual dual-mode sensor for efficient detection of Cry1Ab protein based on the proximity hybridization driven specific desorption of multifunctional probe

Currently, the development of sensitive and visual strategy for Cry1Ab detection, particularly using a switchable dual-mode detection system based on a single component, remains a great challenge. Here, a photoelectrochemical (PEC) and visual dual-mode sensor was designed for Cry1Ab detection based on a proximity hybridization driven multifunctional probe. In the presence of Cry1Ab, specific desorption of the antibody-DNA conjugate was achieved via sufficient proximity hybridization, leading to the selective release of the multifunctional signal probe, i.e., antibody-labeled single-stranded DNA-gold nanoparticles (Ab₁-S1-AuNPs). The released Ab₁-S1-AuNPs reduced the photocurrent signal and produced a colored response, thereby achieving PEC and visual dual-mode detection based on a single component. Owing to the different signal generation mechanisms, two independent signals were obtained simultaneously, which provided self-verification to improve reliability and accuracy. Taking advantage of the PEC sensitive detection and visual prediction, the dual-mode sensor achieved efficient detection of the Cry1Ab protein. The developed sensor was successfully used to determine Cry1Ab in corn, wheat, and soil samples with satisfactory results. This method offers a promising biosensing platform for the on-site detection of Cry1Ab protein.

Advances in upconversion luminescence nanomaterial-based biosensor for virus diagnosis

Various infectious viruses have been posing a major threat to global public health, especially SARS-CoV-2, which has already claimed more than six million lives up to now. Tremendous efforts have been made to develop effective techniques for rapid and reliable pathogen detection. The unique characteristics of upconversion nanoparticles (UCNPs) pose numerous advantages when employed in biosensors, and they are a promising candidate for virus detection. Herein, this Review will discuss the recent advancement in the UCNP-based biosensors for virus and biomarkers detection. We summarize four basic principles that guide the design of UCNP-based biosensors, which are utilized with luminescent or electric responses as output signals. These strategies under fundamental mechanisms facilitate the enhancement of the sensitivity of UCNP-based biosensors. Moreover, a detailed discussion and benefits of applying UCNP in various virus bioassays will be presented. We will also address some obstacles in these detection techniques and suggest routes for progress in the field. These progressions will undoubtedly pose UCNP-based biosensors in a prominent position for providing a convenient, alternative approach to virus detection.

Molecularly Imprinted Polymer Functionalized Bi2S3/Ti3C2TX MXene Nanocomposites for Photoelectrochemical/Electrochemical Dual-Mode Sensing of Chlorogenic Acid

We report the proof-of-concept of molecularly imprinted polymer (MIP) functionalized Bi2S3/Ti3C2TX MXene nanocomposites for photoelectrochemical (PEC)/electrochemical (EC) dual-mode sensing of chlorogenic acid (CGA). Specifically, the in-situ growth of the Bi2S3/Ti3C2TX MXene served as a transducer substrate for molecularly imprinted polymers such as PEC and EC signal generators, due to its high surface area, suitable bandwidth and abundant active sites. In addition, the chitosan as a binder was encapsulated into MIP by means of phase inversion on a fluorine-doped tin dioxide (FTO) electrode. In the determination of CGA as an analytical model, the dual-mode sensor based on MIP functionalized Bi2S3/Ti3C2TX MXene nanocomposites had good selectivity, excellent stability and acceptable reproducibility, which displayed a linear concentration range from 0.0282 μM to 2824 μM for the PEC signal and 0.1412 μM to 22.59 μM for the EC signal with a low detection limit of 2.4 nM and 43.1 nM, respectively. Importantly, two dual-response mode with different transduction mechanisms could mutually conform to dramatically raise the reliability and accuracy of detection compared to single-mode detection. This work is a breakthrough for the design of dual-mode sensors and will provide a reasonable basis for the construction of dual-mode sensor platforms.

Biocatalysis-mediated MOF-to-prussian blue transformation enabling sensitive detection of NSCLC-associated miRNAs with dual-readout signals

Sensitive and accurate miRNAs assay is critical for early diagnosis of non-small-cell lung carcinomas (NSCLC). Herein, we demonstrate a photothermal and electrochemical dual-readout assay method for miRNA detection based on a novel biocatalysis-mediated MOF-to-prussian blue (PB) transformation (BMMPT) strategy and the catalytic hairpin assembly (CHA) amplification strategy. It is found that the Fe²⁺-based MOF (MOF-Fe²⁺) can act as the Fe²⁺ source to react with K₃[Fe(CN)₆], leading to the in-situ formation of prussian blue (PB) on MOF-Fe²⁺. Due the inherent near-infrared (NIR) photothermal conversion ability and electrochemical signal of PB, the resulting PB@MOF-Fe²⁺ is employed to arouse temperature readout or electrochemical signal. The presence of target miRNA-21 triggers the CHA reaction on magnetic beads (MBs), resulting the capture of numerous glucose oxidase (GOx) tags on MBs. The GOx tags then catalyze the generation of H₂O₂ using glucose as substrate. The H₂O₂ is used to inhibit the MOF-to-PB transformation process by oxidizing Fe²⁺ into Fe³⁺, leading to the decrease in temperature and electrochemical readout aroused by PB@MOF-Fe²⁺. By this means, a signal-off assay mode with dual readout is established for miRNA-21. Under the optimal conditions, using temperature readout or electrochemical readout, miRNA-21 can be detected at concentrations as low as 0.3 fM and 0.32 fM, respectively. Moreover, the developed method is successfully applied to evaluate the expression level of miRNA-21 in serum of NSCLC patients. This work not only provides a practical tool for NSCLC diagnosis but also presents the new features of MOF materials as signal transduction tags.

Highly Selective Photoelectrochemical Assay of Arsenate Based on Magnetic Co3O4-Fe3O4 Cubes and the Negative-Background Signal Strategy

Water pollution presents a significant environmental concern on earth. Herein, due to the serious environmental harmfulness of arsenate [As(V)], an iron phthalocyanine (FePc)-induced switchable photocurrent-polarity platform was developed for highly selective assay of As(V). First, magnetic Co₃O₄-Fe₃O₄ cubes were obtained by calcination of the CoFe Prussian blue analogue and then functionalized with oligonucleotide (S1). In the presence of As(V), S1 could be released based on the stronger affinity between As(V) and Co₃O₄-Fe₃O₄ cubes. After magnetic separation by Co₃O₄-Fe₃O₄ cubes, the released S1 was used to trigger the catalytic hairpin assembly (CHA) and hybridization chain reaction, resulting in the formation of lots of G-quadruplex structures on the AgInS₂/ITO electrode. Then, the capture of FePc by the G-quadruplex led to the switch of the photocurrent polarity of the AgInS₂/ITO electrode from the anode to the cathode. Thus, As(V) was sensitively assayed with a low detection limit of 1.0 nM and a wide linear response range from 10 nM to 200 μM. This meets the detection requirement of the World Health Organization for the arsenic concentration in drinking water [less than 10 μg L^-1 (130 nM)]. In addition, whether it was cationic or anionic interferents except phosphate (PO₄^3-), only As(V) could generate the cathodic photocurrent, effectively avoiding the false-positive or false-negative results during As(V) assay. Interestingly, As(V) was also simultaneously separated from the detection system by Co₃O₄-Fe₃O₄ magnetic cubes. The proposed photoelectrochemical platform may have a great potential application for the selective detection of As(V) in environmental fields.

Recent Advances of Nanostructured Materials for Photoelectrochemical Bioanalysis

Nowadays, the emerging photoelectrochemical (PEC) bioanalysis has drawn intensive interest due to its numerous merits. As one of its core elements, functional nanostructured materials play a crucial role during the construction of PEC biosensors, which can not only be employed as transducers but also act as signal probes. Although both chemical composition and morphology control of nanostructured materials contribute to the excellent analytical performance of PEC bioassay, surveys addressing nanostructures with different dimensionality have rarely been reported. In this review, according to classification based on dimensionality, zero-dimensional, one-dimensional, two-dimensional, and three-dimensional nanostructures used in PEC bioanalysis are evaluated, with an emphasis on the effect of morphology on the detection performances. Furthermore, using the illustration of recent works, related novel PEC biosensing patterns with promising applications are also discussed. Finally, the current challenges and some future perspectives in this field are addressed based on our opinions.

Spatiotemporally Controlled DNA Nanoclamps: Single-Molecule Imaging of Receptor Protein Oligomerization

Cell membrane surface receptor proteins play an important role in cellular biological processes. There are numerous methods to detect receptors, yet developing an artificially controlled and specific detection and treatment strategy remains a challenge. Herein, we develop such a strategy based on upconversion nanoparticles (UCNPs) loaded DNA probes that enable two-color ratiometric imaging excitated by a 980 nm laser. The light response controllable signal opening strategy avoids waste during probe transportation and improves sensitivity. Thereby the number of receptors on individual DU145 cell membranes is counted by single-molecule detection. Due to the different expression of specific receptor proteins, the number of single fluorescent dots counted can be used as a basis for distinguishing DU145 from other cells. This work is highly controllable to increase sensitivity, providing a platform for cancer diagnosis and treatment.

Ultrasensitive Double-Channel Microfluidic Biosensor-Based Cathodic Photo-electrochemical Analysis via Signal Amplification of SOD-Au@PANI for Cardiac Troponin I Detection

Interesting double-channel microfluidic chip integration with a sandwich-type cathodic photo-electrochemical (PEC) biosensor is utilized for ultrasensitive and efficient detection of cardiac troponin I (cTnI) based on a signal amplification strategy. The Pd nanoparticles loading on the I-doped bismuth oxybromide with oxygen vacancies (Pd/I:BiOBr-OVs) as a sensing platform can effectively enhance cathodic photocurrent response by improving the visible light absorption ability with I doping, facilitating the efficiency separation of photogenerated electron-hole pairs with OVs, and increasing the electron-transfer rate with Pd loading, where the photogenerated electron could be captured by dissolved O₂ to boost generation of a superoxide anion radical (^•O₂^-). To further enhance the PEC response, a novel superoxide dismutase loaded on gold@polyaniline (SOD-Au@PANI) as a signal amplification label is developed for incubating the detection antibody (dAb). It is particularly noteworthy that SOD can effectively catalyze dismutation of the ^•O₂^- to produce H₂O₂ and O₂, and Au@PANI with a good reduction and catalytic property can catalyze the produced H₂O₂ into H₂O and O₂. Then, the produced O₂ that has been dissolved or adsorbed can capture more photogenerated electrons, resulting in more electron-hole pairs to separate, so as to the cathodic photocurrent signal of this system which can be amplified more significantly. Therefore, a signal amplification cathodic PEC biosensor is prepared for sensitively detecting cTnI, in which a good linearity ranging from 0.1 pg/mL to 100 ng/mL with a low detection limit of 0.042 pg/mL is obtained. Furthermore, the proposed biosensor exhibits excellent sensitivity and high selectivity, which could be extended to detect other disease markers in biological analysis and early disease diagnosis.

A photoelectrochemical self-powered sensor for the detection of sarcosine based on NiO NSs/PbS/Au NPs as photocathodic material

In this study, lead(II) sulfide (PbS) nanocrystals were modified on nickel(II)oxide nanosheets (NiO NSs) via the chemical bath method. Afterwards, Au nanoparticles (NPs) were also modified successfully. A photoelectrochemical (PEC) self-powered platform for detecting sarcosine with high PEC activity was constructed. The capacity of NiO NSs to be loaded with other sensitizing materials was mainly attributed to its porous structure and large specific surface area. Under optimum conditions, the constructed PEC self-powered cathodic sensor for detecting sarcosine exhibited a linear range in 5.0 × 10^-8-5.0 × 10^-2 mol/L with a detection limit (LOD) of 1.7 × 10^-8 mol/L. The biosensor demonstrated good reproducibility, acceptable stability and high specificity, thus confirming its potential application in the detection of other similar substances.

An optic-fiber graphene field effect transistor biosensor for the detection of single-stranded DNA

Herein, a graphene field effect transistor (GFET) was constructed on an optic fiber end face to develop an integrated optical/electrical double read-out biosensor, which was used to detect target single-stranded DNA (tDNA). Two isolated Au electrodes were, respectively, prepared as the drain and source at the ends of an optic fiber and coated with a graphene film to construct a field effect transistor (FET). Probe aptamers modified with fluorophore 6'-carboxy-fluorescein (6'-FAM) were immobilized on the graphene for specific capture of tDNA. Graphene oxide (GO) was introduced to quench 6'-FAM and construct a fluorescence biosensor. Thus, a dual GFET and fluorescence biosensor was integrated on the end-face of an optic fiber. Following synchronous detection by fluorescence and FET methods, results showed satisfactory sensitivity for DNA detection. Compared with conventional biosensors using a single sensing technology, these dual sensing integrated biosensors significantly improved the reliability and accuracy of DNA detection. Furthermore, this proposed technique provides both a new biosensor for single-stranded DNA detection and a strategy for designing multi-sensing integrated biosensors.