A self-powered photoanode-supported photoelectrochemical immunosensor for CYFRA 21-1 detection based on In2O3/In2S3/CdIn2S4 heterojunction

Dual amplification for PEC ultrasensitive aptasensing of biomarker HER-2 based on Z-scheme UiO-66/CdIn2S4 heterojunction and flower-like PtPdCu nanozyme

As an important prognostic indicator in breast cancer, human epithelial growth factor receptor-2 (HER-2) is of importance for assessing prognosis of breast cancer patients, whose accurate and facile analysis are imperative in clinical diagnosis and treatment. Herein, photoactive Z-scheme UiO-66/CdIn2S4 heterojunction was constructed by a hydrothermal method, whose optical property and photoactivity were critically investigated by a range of techniques, combined by elucidating the interfacial charge transfer mechanism. Meanwhile, PtPdCu nanoflowers (NFs) were fabricated by a simple aqueous wet-chemical method, whose peroxidase (POD)-mimicking catalytic activity was scrutinized by representative tetramethylbenzidine (TMB) oxidation in H2O2 system. Taken together, the UiO-66/CdIn2S4 based photoelectrochemical (PEC) aptasensor was established for quantitative analysis of HER-2, where the detection signals were further magnified through catalytic precipitation reaction towards 4-chloro-1-naphthol (4-CN) oxidation (assisted by the PtPdCu NFs nanozyme). The PEC aptasensor presented a broader linear range within 0.1 pg mL-1-0.1 μg mL-1 and a lower limit of detection of 0.07 pg mL-1. This work developed a new PEC aptasensor for ultrasensitive determination of HER-2, holding substantial promise for clinical diagnostics.

Organic photoelectrochemical transistor aptasensor for dual-mode detection of DEHP with CRISPR-Cas13a assisted signal amplification

Emerging organic photoelectrochemical transistors (OPECTs) with inherent amplification capabilities, good biocompatibility and even self-powered operation have emerged as a promising detection tool, however, they are still not widely studied for pollutant detection. In this paper, a novel OPECT dual-mode aptasensor was constructed for the ultrasensitive detection of di(2-ethylhexyl) phthalate (DEHP). MXene/In2S3/In2O3 Z-scheme heterojunction was used as a light fuel for ion modulation in sensitive gated OPECT biosensing. A transistor system based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) converted biological events associated with photosensitive gate achieving nearly a thousand-fold higher current gain at zero bias voltage. This work quantified the target DEHP by aptamer-specific induction of CRISPR-Cas13a trans-cutting activity with target-dependent rolling circle amplification as the signal amplification unit, and incorporated the signal changes strategy of biocatalytic precipitation and TMB color development. Combining OPECT with the auxiliary validation of colorimetry (CM), high sensitivity and accurate detection of DEHP were achieved with a linear range of 0.1 pM to 200 pM and a minimum detection limit of 0.02 pM. This study not only provides a new method for the detection of DEHP, but also offers a promising prospect for the gating and application of the unique OPECT.

Recent Trends in Self-Powered Photoelectrochemical Sensors: From the Perspective of Signal Output

Revolutionary developments in analytical chemistry have led to the rapid development of self-powered photoelectrochemical (PEC) sensors. Different from conventional PEC sensors, self-powered PEC sensors do not require an external power source or complex devices for the sensitive detection of targets. As a result, these sensors have enormous application potential for the development of novel portable sensors. An increasing body of work is making excellent progress toward the implementation of self-powered PEC sensors for detection, but there have been no reviews to date. The present review first introduces the state of the art in the development of self-powered PEC sensors. Then, different types of self-powered PEC sensors are summarized and discussed in detail, including their current, power, and potential. Additionally, single- and dual-photoelectrode systems are classified and systematically compared. Finally, the current developments and major challenges that need to be addressed are also summarized. This review provides valuable insights into the current state of self-powered PEC sensors to promote further progress in this field.

In2O3/Bi2S3 S-scheme Heterojunction-Driven Molecularly Imprinted Photoelectrochemical Sensor for Ultrasensitive Detection of Florfenicol

Florfenicol (FF) raises significant human health and environmental concerns due to its toxicity to the hematology system and the potential spread of antibiotic-resistant genes. Here, a highly sensitive molecularly imprinted photoelectrochemical (PEC) sensor, featuring an In2O3/Bi2S3 S-scheme heterojunction, is proposed to detect FF without an external voltage supply. Compared with conventional II-type heterojunctions, S-scheme heterojunctions efficiently promote carrier separation and enhance the redox capability of the photocatalytic system. This allows more dissolved O2 and H2O molecules to participate in the redox reaction, resulting in an amplified and stabilized photocurrent response. The electron transfer in the S-scheme heterojunction is confirmed via electron spin resonance (ESR). With the molecular imprinting technique, this PEC platform exhibits exceptional selectivity, wide linear range (1.0 × 10-4-1.0 × 104 ng mL-1), low detection limit (6.4 × 10-5 ng mL-1), and applicability in real milk and chicken samples. This work not only showcases a PEC platform for accurately and portably detecting drugs but also proposes a viable approach for designing S-scheme heterojunctions in sensing analysis.

Faraday cage-type self-powered immunosensor based on hybrid enzymatic biofuel cell

Self-powered immunosensors (SPIs) based on enzymatic biofuel cell (EBFC) have low sensitivity and poor stability due to the high impedance of the immune sandwich and the vulnerability of enzymes to environmental factors. Here, we applied the Faraday cage-type sensing mode on a hybrid biofuel cell (HBFC)-based SPI for the first time, which exhibited high sensitivity and stability. Cytokeratin 19 fragment (CYFRA 21-1) was used as a model analyte. Au nanoparticle-reduced graphene oxide (Au-rGO) composite was used as the supporting matrix for immunoprobe immobilized with detection antibody and glucose dehydrogenase (GDH), also the builder for Faraday cage structure on the bioanode in the presence of antigen. After the combination of immunoprobe, antigen, and the antibody on the bioanode, the Faraday cage was constructed in case the AuNP-rGO was applied as a conductive cage for electron transfer from GDH to the bioanode without passing through the poorly conductive protein. With the assistance of the Faraday cage structure, the impedance of the bioanode decreased significantly from 4000 to 300 Ω, representing a decline of over 90%. The sensitivity of the SPI, defined as the changes of open circuit voltage (OCV) per unit concentration of the CYFRA 21-1, was 68 mV [log (ng mL-1)]-1. In addition, Fe-N-C was used as an inorganic cathode material to replace enzyme for oxygen reduction reaction (ORR), which endowed the sensor with 4-week long-term stability. This work demonstrates a novel sensing platform with high sensitivity and stability, bringing the concept of hybrid biofuel cell-based self-powered sensor.

Dual-Modal Biosensor for Staphylococcus aureus Detection Based on a Porphyrin-Based Porous Organic Polymer FePor-TPA with Excellent Peroxidase-like, Catalase-like, and Photoelectrochemical Properties

Bacterial infections seriously harm human health and cause many severe diseases, which triggered urgent demands to exploit specific and sensitive biosensor strategies for Staphylococcus aureus detection. Here, a colorimetric and photoelectrochemical dual-mode biosensor for S. aureus assay based on FePor-TPA was constructed. 2D FePor-TPA thin film and its bulk powder (FePor-TPA) were synthesized by in situ growth on ITO and a solvothermal condition, respectively, both of which exhibited excellent peroxidase-like and catalase-like activity, originating from their metalloporphyrin linkers. Benefiting from the in situ growth on ITO electrodes, the 2D FePor-TPA thin film also possessed a more ordered stacking mode and in turn exhibited good electrical conductivity, stable initial photocurrent, and high sensitivity to O2. As for bulk FePor-TPA, its porous structure and high specific surface area make it a possible scaffold to load an amount of AuNPs, the rabbit anti-Staphylococcus aureus Rosenbach tropina antibody (Ab2), and GOx for constructing the signal probe (GOx/Ab2@Au@FePor-TPA) and realizing catalytic amplification. With these satisfactory features in mind, the 2D FePor-TPA thin film and its bulk powder (FePor-TPA) were utilized to construct a dual and signal-on bioplatform for sensitively and selectively detecting S. aureus, which, as far as we know, has not been reported.

Type-I heterojunction destruction by In situ formation of Bi2S3 for split-type photoelectrochemical aptasensor

Development of new strategies in photoelectrochemical (PEC) sensors is an important way to realize sensitive detection of biomolecule. In this study, mesoporous silica nanospheres (MSNs)-assisted split-type PEC aptasensor with in situ generation of Bi₂S₃ was proposed to achieve reliable detection of prostate-specific antigen (PSA). To be more specific, this bioresponsive release system will release large amounts of Na₂S by the reaction between PSA and aptamer that capped Na₂S-loading MSNs. Next, the Na₂S reacts with Bi to yield BiOI/BiOBr/Bi₂S₃ composite, which leads to an alteration in the electron-hole transfer pathway of the photoelectric material and a decrease in the response. As the PSA concentration increases, more Na₂S can be released and lower photocurrent is obtained. The linear range under the optimal experimental conditions is 10 pg·mL^-1-1 μg⋅mL^-1, and the detection limit is 1.23 pg⋅mL^-1, which has satisfactory stability and anti-interference.

A dual-photoelectrode fuel cell-driven self-powered aptasensor based on the 1D/2D In2S3/MoS2@Fe-CNTs heterojunction for the ultrasensitive detection of Staphylococcus aureus

A novel dual-electrode photo-fuel cell (PFC)-driven self-powered aptasensor was manufactured for the sensitive and selective detection of Staphylococcus aureus (S. aureus) using the one-dimensional (1D)/2D Schottky heterojunction comprising bimetallic indium/molybdenum sulfide nanosheets and iron-doped carbon nanotube (Fe-CNT) (denoted as In₂S₃/MoS₂@Fe-CNTs) as the photocathode. Given the generation of a robust interface at In₂S₃/MoS₂ and Fe-CNTs, the charge separation and transfer ability of photoexcited electron-hole pairs were enforced, thus improving the output voltage of the assembled PFC. In addition, the numerous active sites of the 1D/2D In₂S₃/MoS₂@Fe-CNTs Schottky heterojunction enabled the immobilization of large amounts of aptamer. Accordingly, the proposed PFC-driven self-powered aptasensor exhibited a wide linear range in 10-1 × 10⁷ CFU mL^-1 with a detection limit of 1.2 CFU mL^-1 toward S. aureus. High selectivity, excellent reproducibility, good stability, and acceptable regenerability, as well as great potential practicality, were also achieved for the detection of S. aureus using the developed PFC-driven self-powered aptasensor. This work not only provides a new photoactive material based on a robust 1D/2D Schottky heterojunction, but also constructs a novel PFC-based self-powered aptasensing strategy based on dual-photoelectrodes and with satisfactory performance for the detection of foodborne pathogens in diverse environments.

Design of NiS@Ni3S2/CdS heterostructure with intimate contact interface for sensitive photoelectrochemical detection of lincomycin

Owing to their internal electric field effect and abundant photo-induced carriers, photoactive heterostructured materials are considered a feasible approach to improve the sensitivity of a photoelectrochemical (PEC) sensor. Herein, a novel NiS@Ni₃S₂/CdS heterostructure composite is derived from Ni-loaded zeolitic imidazolate framework (Ni-ZIF). The PEC experiments showed the NiS@Ni₃S₂/CdS composite exhibits superior photocurrent response than NiS@Ni₃S₂ and CdS. This is attributed to the fact that the type II heterojunction of NiS@Ni₃S₂/CdS with a tightly connected interface reduces the transport distance of carriers and facilitates electron-hole separation. Next, using the NiS@Ni₃S₂/CdS modified electrode, an aptamer/glutaraldehyde/chitosan/NiS@Ni₃S₂/CdS/ITO PEC biosensor is developed, which exhibits excellent sensitivity for lincomycin (Lin) detection with a wide linear range (0.0001 ∼ 1.25 nM) and a low detection limit of 0.067 pM. The prepared sensor is further employed to monitor Lin in the actual milk. The results confirm that the prepared sensing electrode displays good selectivity, repeatability and stability.

A novel electrochemical impedance immunosensor for the quantification of CYFRA 21-1 in human serum

A sensitive, simple, and reliable immunosensor was constructed to detect the lowest alteration of a fragment of cytokeratin subunit 19 (CYFRA 21-1), a protein lung carcinoma biomarker. The proposed immunosensor was manufactured with a carbon black C45/polythiophene polymer-containing amino terminal groups (C45-PTNH₂) conductive nanocomposite, resulting in an excellent, biocompatible, low-cost, and electrically conductive electrode surface. Anti-CYFRA 21-1 biorecognition molecules were attached to the electrode thanks to the amino terminal groups of the used PTNH₂ polymer with a relatively simple procedure. All electrode surfaces after modifications were characterized by electrochemical, chemical, and microscopic techniques. Electrochemical impedance spectroscopy (EIS) was also utilized for the evaluation of the analytical feature of the immunosensor. The charge transfer resistance of the immunosensor signal was correlated with the CYFRA 21-1 concentration in the concentration range 0.03 to 90 pg/mL. The limit of detection (LOD) and the limit of quantification (LOQ) of the suggested system were 4.7 fg/mL and 14.1 fg/mL, respectively. The proposed biosensor had favorable repeatability and reproducibility, long storage stability, excellent selectivity, and low cost. Furthermore, it was applied to determine CYFRA 21-1 in commercial serum samples, and satisfactory recovery results (98.63-106.18%) were obtained. Thus, this immunosensor can be offered for clinical purposes as a rapid, stable, low-cost, selective, reproducible, and reusable tool.

Novel design constructed In2S3@SnO2 hollow heterojunctions by insufficiently etched MOFs as framework for photoelectrochemical bioanalysis

Compared to sufficiently etched MOFs materials, insufficiently etched MOFs materials tend to display unsatisfactory performance due to their immature structure and have been eliminated from scientific research. Herein, this work reported a novel In₂S₃@SnO₂ heterojunction (In₂S₃@SnO₂-HSHT) materials, which were stably synthesized in high temperature aqueous environment and equipped extraordinary photoelectrochemical (PEC) properties, fabricated by a succinct hydrothermal synthesis method using insufficiently etched MIL-68 as a self-sacrificing template. Compared with the control groups and In₂S₃@SnO₂ heterojunctions with collapse morphology synthesized by sufficiently etched MIL-68 in high temperature aqueous environment, In₂S₃@SnO₂-HSHT synthesized from insufficiently etched MIL-68 as a template had a massively enhanced light-harvesting capability and generated more photoinduced charge carriers due to its well-preserved hollow structure. Therefore, based on outstanding PEC performance of In₂S₃@SnO₂-HSHT, the established PEC label-free signal-off immunosensor to detect CYFRA 21-1, revealing vivid selectivity, stability, and reproducibility. This novel strategy adopted the insufficient chemical etching method neglected by the mainstream chemical etching approaches, which solved the challenge that the stability of the sufficient etched MOFs with hollow structure cannot be maintained under the subsequent high temperature aqueous reaction conditions, and was further applied to the design of hollow heterojunction materials for photoelectrochemical fields.

In2O3/CdIn2S4 heterojunction-based photoelectrochemical immunoassay of carcinoembryonic antigen with enzymatic biocatalytic precipitation for signal amplification

This work reported a split-type photoelectrochemical (PEC) immunoassay for the detection of carcinoembryonic antigen (CEA) based on target-induced biocatalytic precipitation (BCP) by using In₂O₃/CdIn₂S₄ heterojunctions as the photosensitizers. The synthesized In₂O₃/CdIn₂S₄ heterojunctions improved the efficiency of charge separation and shortened the electron convey path to enhance the photocurrent, thus exhibiting high conductivity and low complexation rates of photogenerated electrons and holes. In the presence of CEA, horseradish peroxidase (HRP) catalyzed 4-chloro-1-naphthol (4-CN) to produce benzo-4-chloro-hexadienone (4-CD) through H₂O₂. Then, 4-CD was deposited onto the surface of In₂O₃/CdIn₂S₄ to reduce the photocurrent and realized the signal amplification. The PEC immunoassay revealed an excellent photocurrent toward target CEA within a wide range of 0.01-50 ng mL^-1 at a low limit of detection of 2.8 pg mL^-1 under the optimum conditions. Multiple switching light excitation tests demonstrated the good reliability and stability of the fabricated PEC biosensor. The accuracy was acceptable in comparison with human CEA enzyme-linked immunosorbent assay (ELISA) kit.

Antigen-Down PEC Immunosensor for CYFRA21-1 Detection Based on Photocurrent Polarity Switching Strategy

In this work, an antigen-down photoelectrochemical (PEC) immunosensor based on a signal polarity switching strategy for the detection of cytokeratin 19 fragment 21-1 (CYFRA21-1) was proposed. 3,4,9,10-Perylene tetracarboxylic acid (PTCA) is a conjugated organic dye containing five benzene nuclei, which has excellent film-forming and optical properties. PTCA sensitized by SnS₂ can further improve the basal signal and the stability of the PEC immunosensor. Moreover, avidin-functionalized CuInS₂ as a signal probe can convert the basal anodic photocurrent to a cathodic photocurrent. Therefore, the PEC sensor realized the photocurrent polarity conversion before and after labeling. With avidin-functionalized CuInS₂, the polarity of the photocurrent was changed once CYFRA21-1 was detected. Therefore, the PEC immunosensor owns high sensitivity. The linear range of the immunosensor for the detection of CYFRA21-1 is 0.00001-500 ng·mL^-1, and the detection limit is 3.5 fg·mL^-1. The PEC immunosensor has good stability, high selectivity, and good repeatability. This work may provide a new way for the detection of CYFRA21-1 and other proteins.

Self-powered Aptasensors Made with the In2O3-In2S3-Ti3C2 Composite for Dual-mode Detection of Microcystin-LR

A dual-mode self-powered aptasensing platform of photoelectrochemical (PEC) and photofuel cell (PFC) was constructed for Microcystin-LR (MC-LR) detection. Specifically, the In₂O₃-In₂S₃-Ti₃C₂ (IO-IS-TC) composite was facilely assembled on the base of MOF-derived In₂O₃ hollow tubulars, and the integrated mechanism and photoconversion efficiency are proposed and discussed in detail. Herein, a promising dual-mode sensing platform was constructed using the IO-IS-TC composite as a photoanode matrix with higher output power and obvious photocurrent response. Moreover, the dual-mode sensing platform did not require external bias and the addition of sacrificial agents under visible light irradiation. The enhanced PEC properties can be attributed to the matched energy level of ternary components and the improved separation of photogenerated carriers. Moreover, aptamer-based recognition was adopted to catch MC-LR molecules, which realized the highly sensitive and selective detection. The PFC aptasensor was exhibited at 50-5 × 10⁵ pmol/L with a detection limit of 17.4 pmol/L, and the PEC aptasensor was realized from 0.5 to 4 × 10⁵ pmol/L with a detection limit of 0.169 pmol/L. The proposed aptasensing platform showed good specificity, reproducibility, and stability, which paved the way for the construction of a fast and ultrasensitive PEC sensing methodology for environmental analysis.

Ultrasensitive photoelectrochemical immunosensor based on Dual-Photosensitive electrodes

In the study, a photoelectrochemical (PEC) immunosensor based on dual-photosensitive electrodes was developed for cardiac troponin I (cTnI) detection. The sensing photocathode with biometric functions was prepared by CuInS₂ and narrow band gap semiconductor In₂S₃ as the counter electrode. In this way, the separation of photoanode and biometric events was realized, and the ability of stability of the immunosensor could be effectively improved. Moreover, the attraction to the photogenerated electrons (e^-) from photoanode would be increased by the abundant holes (h⁺) of photocathode, under the radiation of light. This tremendously improves the photoelectric response, which further improves the sensitivity of the immunosensor. The controllable-synthesis uncomplicated photoelectric material not only accords with the principle of simplicity of electrode modification but also makes the immunosensor more conducive to the practical application. Additionally, even in the case of zero bias voltage, the constructed PEC immunosensor can operate with high efficiency, namely, self-powered. The immunosensor could provide the quantitative readout photocurrent to a concentration of cTnI in the range of 0.10 pg/mL to 1.00 μg/mL and the detection limit was 0.0113 pg/mL under the optimal experimental conditions. With favorable performance in terms of anti-interference, stability, specificity and reproducibility, this immunosensor will provide new prospects for general PEC bioanalysis development.

Self-powered photoelectrochemical biosensor with inherent potential for charge carriers drive

Self-powered photoelectrochemical (PEC) sensing platform without external voltage has provided a breakthrough in the development of biosensors, however, it is necessary to find suitable Fermi energy level difference between photoanode materials and photocathode materials as the driving force. Herein, the self-powered PEC sensor was developed to combine the advantages of both the photoanode (SnS₂/In₂S₃) and the photocathode (CuInS₂). The sufficient Fermi level differentiation between the photoanode with the photocathode not only resulted in an evident photocurrent response vis tuning the electron transfer but avoided redox reactions of extra electron donors/acceptors to enhance the accuracy of the sensor. The biological target was immobilized on the photocathode, which allowed the sensor to possess a good anti-interference capability for the detection of real samples. The proposed PEC sensor exhibits good sensitivity for the cytokeratin 19 fragment (CYFRA21-1) detection and a low limit of detection (LOD) of 6.57 fg mL^-1. Moreover, the as-purposed PEC system with good anti-interference capability and accuracy has implications for the detection of other biomarkers.

Detection of NSE by a photoelectrochemical self-powered immunosensor integrating RGO photocathode and WO3/Mn:CdS nanomaterial photoanode

Generally, the photoanodic photoelectrochemical (PEC) immunoassay method has an outstanding photocurrent and low detection limit, but its poor anti-interference ability in the detection of real samples restricts its performance. The photocathode immunoassay method has an excellent ability to see interference in actual sample detection, but it has its own defect in that the photocurrent is not obvious. Here, a promising new cathodic PEC immunosensing platform is reported, which integrates a photocathode and photoanode. The photoanode and photocathode are WO₃/Mn:CdS composite modified and reduced graphene oxide (RGO) modified indium tin oxide (ITO) electrodes, respectively. In addition to an excellent PEC response, the immunosensor constructed by the integrating the photoanode and photocathode also has good anti-interference ability in actual sample analysis. The constructed immunosensor achieves accurate detection of NSE with a range from 5.0 pg/mL to 20 ng/mL, and the limit of detection (LOD) is 1.2 pg/mL. The proposed immunoassay method has good stability, selectivity and reproducibility. Moreover, it introduces new ideas for the construction of PEC immunosensors.

Novel Anti-Interference Strategy for a Self-Powered Sensor: Mediator-Free and Biospecific Photocathode Interface

As a new electrochemical sensing concept, a self-powered sensor shows a good application prospect in the field of analysis. However, it is still a great challenge to improve the anti-interference capability of sensors through reasonable design. In this study, we investigated the difference between the single photoanode and photocathode self-powered sensor and combined the advantages of these two aspects to fabricate a mediator-free self-powered aptasensor based on the dual-photoelectrode system, which combined the biological events from the photocathode. The biological events occurred at the photocathode could avoid the interference caused by the generated hole oxidation of reducing small molecules in the real sample on the photoanode surface, which was helpful to enhance the anti-interference capability of the sensor. Moreover, due to the sufficient Fermi level differentiation between two photoelectrodes, the redox mediator was not necessary. This could avoid the redox reaction caused by the introduction of extra electron donors or electron acceptors occurring before the photoelectrical behavior, thus improving the accuracy of the sensor. According to the influence of the generated biological conjugate on the external circuit, electron transmission between interfaces, and the obstruction of visible light irradiation, the sensitive and accurate detection of the analytical model was achieved. This work provided a proof-of-concept for the establishment of a mediator-free dual-photoelectrode self-powered sensing platform with high sensitivity and strong anti-interference performance.

A novel electrochemical lung cancer biomarker cytokeratin 19 fragment antigen 21-1 immunosensor based on Si3N4/MoS2 incorporated MWCNTs and core-shell type magnetic nanoparticles

Lung cancer is one of deadliest and most life threatening cancer types. Cytokeratin 19 fragment antigen 21-1 (CYFRA 21-1) is a significant biomarker for the diagnosis of non-small cell lung cancer (NSCLC). Due to these reasons, a novel electrochemical immunosensor based on a silicon nitride (Si3N4)-molybdenum disulfide (MoS2) composite on multi-walled carbon nanotubes (Si3N4/MoS2-MWCNTs) as an electrochemical sensor platform and core-shell type magnetic mesoporous silica nanoparticles@gold nanoparticles (MMSNs@AuNPs) as a signal amplifier was presented for CYFRA21-1 detection in this study. Capture antibody (Ab1) immobilization on a Si3N4/MoS2-MWCNT modified glassy carbon electrode (Si3N4/MoS2-MWCNTs/GCE) was firstly successfully performed by stable electrostatic/ionic interactions between the -NH2 groups of the capture antibody and the polar groups of Si3N4/MoS2. Then, specific antibody-antigen interactions between the electrochemical sensor platform and the signal amplifier formed a novel voltammetric CYFRA21-1 immunosensor. The prepared composite materials and electrochemical sensor surfaces were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A linearity range of 0.01-1.0 pg mL-1 and a low detection limit (LOD) of 2.00 fg mL-1 were also obtained for analytical applications. Thus, the proposed immunosensor based on Si3N4/MoS2-MWCNTs and MMSNs@AuNPs has great potential for medical diagnosis of lung cancer.