Electrochemical immunosensor constructed using TiO2 nanotubes as immobilization scaffold and tracing tag

A Branched Rutile/Anatase Phase Structure Electrode with Enhanced Electron-Hole Separation for High-Performance Photoelectrochemical DNA Biosensor

A photoelectrochemical (PEC) detection platform was built based on the branched rutile/anatase titanium dioxide (RA-TiO₂) electrode. Theoretical calculations proved that the type-II band alignment of rutile and anatase could facilitate charge separation in the electrode. The self-generated electric field at the interface of two phases can enhance the electron transfer efficiency of the electrode. Carboxylated CdTe quantum dots (QDs) were applied as signal amplification factors. Without the target DNA presence, the CdTe QDs were riveted to the surface of the electrode by the hairpin probe DNA. The sensitization of CdTe QDs increased the photocurrent of the electrode significantly. When the target DNA was present, the structural changes of the hairpin probe DNA resulted in the failure of the sensitized structure. Benefiting from excellent electrode structure design and CdTe QDs sensitization strategy, the PEC assays could achieve highly sensitive and specific detection of target DNA in the range of 1 fM to 1 nM, with a detection limit of 0.23 fM. The electrode construction method proposed in this article can open a new avenue for the preparation of more efficient PEC sensing devices.

Redox-labelled detection probe enabled immunoassay for simultaneous detection of multiple cancer biomarkers

Some of the cancer biomarkers often lack specificity and sensitivity; thus, simultaneous detection of multiple biomarkers can make the diagnosis more accurate. Also, simple sensing system without utilization of extra reagents like mediator or substrate during detection event is desirable for point-of-care testing. To address this, mediator and substrate-free amperometric biosensor for simultaneous detection of cancer biomarkers carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) have been demonstrated by designing two different redox-labelled detection probes. Colloidal nanoparticles of polyaniline-pectin conjugated with AFP antibody along with ferrocene and silver nanoparticles conjugated with CEA antibody along with anthraquinone were used as redox probes to bind with AFP and CEA during the detection event. Sensor constructed using carboxylic acid tethered polyaniline as immobilization matrix displayed 5 times wider linear range than conventional polyaniline for AFP and CEA detection by sandwich electrochemical assay. The detection limit was 30 pg mL^-1 for AFP and 80 pg mL^-1 for CEA. The biosensor displayed appropriate sensitivity, good specificity, and negligible cross-reactivity between the two targets. The proposed sensor was used to determine APF and CEA in human blood serum. The strategy demonstrated can be further extended for detection of panel of cancer biomarkers by designing appropriate redox probes.

Synthesis of Metal–Organic Frameworks Quantum Dots Composites as Sensors for Endocrine-Disrupting Chemicals

Hazardous chemical compounds such as endocrine-disrupting chemicals (EDCs) are widespread and part of the materials we use daily. Among these compounds, bisphenol A (BPA) is the most common endocrine-disrupting chemical and is prevalent due to the chemical raw materials used to manufacture thermoplastic polymers, rigid foams, and industrial coatings. General exposure to endocrine-disrupting chemicals constitutes a serious health hazard, especially to reproductive systems, and can lead to transgenerational diseases in adults due to exposure to these chemicals over several years. Thus, it is necessary to develop sensors for early detection of endocrine-disrupting chemicals. In recent years, the use of metal–organic frameworks (MOFs) as sensors for EDCs has been explored due to their distinctive characteristics, such as wide surface area, outstanding chemical fastness, structural tuneability, gas storage, molecular separation, proton conductivity, and catalyst activity, among others which can be modified to sense hazardous environmental pollutants such as EDCs. In order to improve the versatility of MOFs as sensors, semiconductor quantum dots have been introduced into the MOF pores to form metal–organic frameworks/quantum dots composites. These composites possess a large optical absorption coefficient, low toxicity, direct bandgap, formidable sensing capacity, high resistance to change under light and tunable visual qualities by varying the size and compositions, which make them useful for applications as sensors for probing of dangerous and risky environmental contaminants such as EDCs and more. In this review, we explore various synthetic strategies of (MOFs), quantum dots (QDs), and metal–organic framework quantum dots composites (MOFs@QDs) as efficient compounds for the sensing of ecological pollutants, contaminants, and toxicants such as EDCs. We also summarize various compounds or materials used in the detection of BPA as well as the sensing ability and capability of MOFs, QDs, and MOFs@QDs composites that can be used as sensors for EDCs and BPA.

A label-free electrochemical immunosensor based on a gold-vertical graphene/TiO2 nanotube electrode for CA125 detection in oxidation/reduction dual channels

A label-free immunosensor was constructed in oxidation and reduction dual channel mode for the trace detection of cancer antigen 125 (CA125) in serum. The gold-vertical graphene/titanium dioxide (Au-VG/TiO₂) electrode was used as the signal-amplification platform, and cytosine and dopamine were used as probes in the oxidation and reduction channels, respectively. VG nanosheets were synthesized on a TiO₂ nanotube array via chemical vapor deposition (CVD), and Au nanoparticles were deeply embedded on the surface and in the root of the VG nanosheets via electrodeposition. The CA125 antibody was then directly immobilized onto the electrode surface, benefitting from its natural affinity for Au nanoparticles. In the oxidation and reduction channels the CA125 antibody-Au-VG/TiO₂ immune electrode had the same response concentration range (0.01-1000 mU∙mL^-1) for the determination of the CA125 antigen. However, the oxidation channel had a higher sensitivity (14.82 μA•(log(mU•mL^-1))^-1 at a working potential of ~ 1.25 V vs. SCE), lower detection limit (0.0001 mU∙mL^-1), higher stability, and lower performance deviation than the reduction channel. This immunosensor was successfully used for CA125 detection in human serum. The recoveries of spiked serum samples ranged from 99.8 ± 0.5 to 100 ± 0.4%. The study on the difference in the sensing performance between oxidation and reduction channels provides a preliminary experimental reference for exploring dual-channel synchronous detection immunosensors and verifying the accuracy of the assay based on dual-channel data, which will promote the development of reliable electrochemical immunosensor technology.

In situ growth of WO3/BiVO4 nanoflowers onto cellulose fibers to construct photoelectrochemical/colorimetric lab-on-paper devices for the ultrasensitive detection of AFP

In this work, novel dual-mode lab-on-paper devices based on in situ grown WO₃/BiVO₄ heterojunctions onto cellulose fibers, as signal amplification probes, were successfully fabricated by the integration of photoelectrochemical (PEC)/colorimetric analysis technologies into a paper sensing platform for the ultrasensitive detection of alpha-fetoprotein (AFP). Specifically, to achieve an impressive PEC performance of the lab-on-paper device, the WO₃/BiVO₄ heterojunction was in situ grown onto the surface of cellulose fibers assisted with Au nanoparticle (Au NP) functionalization for enhancing the conductivity of the working zone of the device. With the target concentration increased, more immune conjugates could be captured by the proposed paper photoelectrode, which could lead to a quantitative decrease in the photocurrent intensity, eventually realizing the accurate PEC signal readout. To meet the requirement of end-user application, a colorimetric signal readout system was designed for the lab-on-paper device based on the color reaction of 3,3'5,5'-tetramethylbenzidine (TMB) oxidized by WO₃/BiVO₄ nanoflowers in the presence of H₂O₂. Noticeably, it is the first time that the WO₃/BiVO₄ heterojunction is in situ grown onto cellulose fibers, which enhances the sensitivity in view of both their PEC activity and catalytic ability. By controlling the conversion process of hydrophobicity and hydrophilicity on the lab-on-paper device combined with diverse origami methods, the dual-mode PEC/colorimetric signal output for the ultrasensitive AFP detection was realized. Under optimal conditions, the proposed dual-mode lab-on-paper device could enable the sensitive PEC/colorimetric diagnosis of AFP in the linear range of 0.09-100 ng mL^-1 and 5-100 ng mL^-1 with the limit of detection of 0.03 and 1.47 ng mL^-1, respectively.

A Photoelectrochemical Platform Based on Polyaniline-Modified Titanium Dioxide Facet Heterostructure

A photoelectrochemical (PEC) electrode for glucose detection was built based on polyaniline (PANI) modified titanium dioxide heterojunction (FH-TiO₂) structures. Ultrathin titanium dioxide (TiO₂) nanosheets are assembled onto rutile nanorods (TiO₂ NRs). Experiments show that the main exposed faces of these nanosheets are (101) or (111) crystal planes. Proven by theoretical calculation, the bottom of the conduction band (CB) of (111) is 0.15 eV lower than the bottom of the conduction band of (101). Therefore, when the material is excited by light, photogenerated electrons are able to transfer from the conduction band of (101) to the conduction band of (111). PANI was introduced as a medium to effectively conduct photogenerated charges between glucose oxidase and titanium dioxide. A photoelectric detection electrode for glucose was fabricated by loading glucose oxidase onto PANI@FH-TiO₂. This electrode showed excellent performance in 0.2-1.0 mM linear range with a sensitivity 15.63 μA mM^-1 cm^-2 and 1.0-15.0 mM linear range with a sensitivity of 1.42 μA mM^-1 cm^-2.

Photoelectrochemical IL-6 Immunoassay Manufactured on Multifunctional Catecholate-Modified TiO2 Scaffolds

There is an increasing interest in using photoelectrochemistry for enhancing the signal-to-noise ratio and sensitivity of electrochemical biosensors. Nevertheless, it remains challenging to create photoelectrochemical biosensors founded on stable material systems that are also easily biofunctionalized for sensing applications. Herein, a photoelectrochemical immunosensor is reported, in which the concentration of the target protein directly correlates to a change in the measured photocurrent. The material system for the photoelectrode signal transducer involves using catecholate ligands to modify the properties of TiO₂ nanostructures in a three-pronged approach of morphology tuning, photoabsorption enhancement, and facilitating bioconjugation. The catecholate-modified TiO₂ photoelectrode is combined with a signal-off direct immunoassay to detect interleukin-6 (IL-6), a key biomarker for diagnosing and monitoring various diseases. Catecholate ligands are added during hydrothermal synthesis of TiO₂ to enable the growth of three-dimensional nanostructures to form highly porous photoelectrodes that provide a three-dimensional scaffold for immobilizing capture antibodies. Surface modification by catecholate ligands greatly enhances photocurrent generation of the TiO₂ photoelectrodes by improving photoabsorption in the visible range. Additionally, catecholate molecules facilitate bioconjugation and probe immobilization by forming a Schiff-base between their -COH group and the -NH₂ group of the capture antibodies. The highest photocurrent achieved herein is 8.89 μA cm^-2, which represents an enhancement by a factor of 87 from unmodified TiO₂. The fabricated immunosensor shows a limit-of-detection of 3.6 pg mL^-1 and a log-linear dynamic range of 2-2000 pg mL^-1 for IL-6 in human blood plasma.

Enhanced photoelectrochemical biosensing performance for Au nanoparticle–polyaniline–TiO2 heterojunction composites

A new photoelectrochemical (PEC) sensing platform comprising TiO₂ nanotube arrays (TiONTAs), polyaniline (PANI), and gold nanoparticles (AuNPs) was successfully fabricated. After loading the enzyme, this Au–PANI–TiONTA electrode showed excellent response to glucose at a linear range of 2–36 mM with a 0.02 mM detection limit. Good PEC performance was obtained due to the following advantages of the material: high visible-light harvesting ability for excellent light trapping capacity of PANI and AuNPs, good separation of the photo-induced charges related to the specific Au–PANI–TiONTA heterostructure, efficient electrode surface reaction kinetics derived from the large specific surface area of TiONTAs and improved electrode catalytic activity. This work proposed a new and general PEC enzymatic format and can be extended to prepare different PEC biosensors for biomolecules such as DNA, proteins and substrates of oxidases.

A novel photoelectrode for glucose PEC biosensing composed of TiONTAs, PANI, and AuNPs was successfully obtained. The GOx@Au–PANI–TiONTA electrode exhibited a wide response range (2–36 mM) with a low detection limit (0.02 mM) and good stability.

Facile synthesis of novel reduced graphene oxide@polystyrene nanospheres for sensitive label-free electrochemical immunoassay

Nanosized reduced graphene oxide@polystyrene nanospheres were first synthesized and further exploited for highly sensitive label-free electrochemical immunoassay applications.

Amplified oxygen reduction signal at a Pt-Sn-modified TiO2 nanocomposite on an electrochemical aptasensor

In this work, a metallic composite with strong electrocatalytic property was designed by uniformly decorating Pt and Sn nanoparticles on the surface of TiO₂ nanorods (Pt-Sn@TiO₂). A detection scheme was then developed based on a dual signal amplification strategy involving the Pt-Sn@TiO₂ composite and exonuclease assisted target recycling. The Pt-Sn@TiO₂ composite exhibited an enhanced oxygen reduction current owing to the synergistic effect between Pt and Sn, as well as high exposure of Pt (111) crystal face. Initially, a Pt-Sn@TiO₂ modified glassy carbon electrode produced an amplified electrochemical signal for the reduction of dissolved oxygen in the analyte solution. Next, a DNA with a complementary sequence to a streptomycin aptamer (cDNA) was immobilised on the Pt-Sn@TiO₂ modified electrode, followed by the streptomycin aptamer that hybridised with cDNA. The corresponding oxygen reduction current was diminished by 51% attributable to the hindrance from the biomolecules. After a mixture of streptomycin and RecJ_f exonuclease was introduced, both the streptomycin-aptamer complex and the cDNA were cleaved from the electrode, making the Pt-Sn and Pt (111) surface available for oxygen reduction. RecJ_f would also release streptomycin from the streptomycin-aptamer complex, allowing it to complex again with aptamers on the electrode. This has then promoted a cyclic amplification of the oxygen reduction current by 85%, which is quantitatively related to streptomycin. Under optimal conditions, the aptasensor exhibited a linear range of 0.05-1500 nM and a limit of detection of 0.02±0.0045 nM streptomycin. The sensor was then used in the real-life sample detection of streptomycin to demonstrate its potential applications to bioanalysis.

A novel enzyme-free electrochemical biosensor for rapid detection of Pseudomonas aeruginosa based on high catalytic Cu-ZrMOF and conductive Super P

Pseudomonas aeruginosa (P. aeruginosa) is one of the most intractable multidrug-resistant bacteria of nosocomial infections. The conventional detection methods for P. aeruginosa are time-consuming or low detection sensitivity. Here, a novel enzyme-free electrochemical biosensor was constructed to detect P. aeruginosa rapidly and sensitively. Firstly, the ZrMOF with large surface area was synthesized, which offers excellent adsorption. Further, it was connected with a specific amount of Cu²⁺ to synthesize Cu-ZrMOF with high catalytic activity. Then the Cu-ZrMOF@Aptamer@DNA nanocomposite was composed and served as the signal probe to catalyse the decomposition of H₂O₂. Moreover, high conductive Super P was introduced to increase the electron transfer for satisfactory detection sensitivity. The proposed biosensor was constructed and used to quantify P. aeruginosa with a wide linearity range of 10-10⁶ CFU mL^-1 and a low limit of detection of 2 CFU mL^-1 (S/N = 3). Compared with conventional methods, the new method of present biosensor is more sensitive, and less time-consuming (only within 120 min). The analytical performance evaluation indicated that the biosensor exhibits good reproducibility and specificity. Finally, the biosensor was successfully applied to quantify P. aeruginosa in spiked urine samples. These results show that the proposed electrochemical biosensor might be a potential laboratory tool for detecting P. aeruginosa in the clinic.

A visible light photoelectrochemical sandwich aptasensor for adenosine triphosphate based on MgIn2S4-TiO2 nanoarray heterojunction

This work designed a MgIn₂S₄-TiONA heterojunction by growing MgIn₂S₄ nanoplates on TiO₂ nanowire array (TiONA) for preparation of visible light photoelectrochemical (PEC) sensing platform. The heterojunction exhibited strong absorption of visible light, large surface area and high loading of biomolecules, leading to high sensing sensitivity. Using adenosine triphosphate (ATP), a marker of cell vitality, as the target model, a PEC sandwich aptasensor was constructed by immobilizing capture DNA₁ on MgIn₂S₄ surface. In the presence of ATP and signal DNA₂ with terminal ferrocene as the electron donor, a sandwiched DNA₁-ATP-DNA₂ complex could be formed on the PEC aptasensor. The aptasensor showed excellent performance with a wide linear range from 50 fM to 100 nM and a detection limit of 20 fM. The sensing performance including specificity, reproducibility, stability and practical use were also evaluated, showing promising application of the MgIn₂S₄-TiONA heterojunction in PEC biosensing.

A highly sensitive electrochemical aptasensor for detection of microcystin-LR based on a dual signal amplification strategy

In this work, a sensitive and selective electrochemical aptasensor for determination of microcystin-LR (MC-LR) was developed based on a dual signal amplification system consisting of a novel ternary composite and horseradish peroxidase (HRP). The ternary composite was prepared by depositing gold nanoparticles (AuNPs) on molybdenum disulfide (MoS2) covered TiO2 nanobeads (TiONBs). MoS2 nanosheet modified TiONBs provided a large surface area for immobilization of AuNPs and biomolecules. The ternary composite also possesses an improved electron transfer and catalytic capability. To construct the aptasensor, thiolated MC-LR aptamers were immobilized on the AuNP@MoS2-TiONB modified electrode through a gold-sulfur bond. Then, biotin-cDNA with a sequence complementary to the MC-LR aptamer competed with MC-LR for binding to the immobilized aptamer. The current signal catalyzed by avidin-HRP decreased with the increase of MC-LR, based on which a linear range of 0.005-30 nM and a detection limit of 0.002 nM were obtained.

An investigation into non-covalent functionalization of a single-walled carbon nanotube and a graphene sheet with protein G:A combined experimental and molecular dynamics study

Investigation of non-covalent interaction of hydrophobic surfaces with the protein G (PrG) is necessary due to their frequent utilization in immunosensors and ELISA. It has been confirmed that surfaces, including carbonous-nanostructures (CNS) could orient proteins for a better activation. Herein, PrG interaction with single-walled carbon nanotube (SWCNT) and graphene (Gra) nanostructures was studied by employing experimental and MD simulation techniques. It is confirmed that the PrG could adequately interact with both SWCNT and Gra and therefore fine dispersion for them was achieved in the media. Results indicated that even though SWCNT was loaded with more content of PrG in comparison with the Gra, the adsorption of the PrG on Gra did not induce significant changes in the IgG tendency. Several orientations of the PrG were adopted in the presence of SWCNT or Gra; however, SWCNT could block the PrG-FcR. Moreover, it was confirmed that SWCNT reduced the α-helical structure content in the PrG. Reduction of α-helical structure of the PrG and improper orientation of the PrG-SWCNT could remarkably decrease the PrG tendency to the Fc of the IgG. Importantly, the Gra could appropriately orient the PrG by both exposing the PrG-FcR and also by blocking the fragment of the PrG that had tendency to interact with Fab in IgG.

Electrochemical performance of myoglobin based on TiO2-doped carbon nanofiber decorated electrode and its applications in biosensing

A new biosensing strategy based on a TiO₂-doped carbon nanofiber (CNF) composite modified electrode was developed. TiO₂@CNF was prepared by electrospinning with further carbonization, before being characterized by various methods and used for electrode modification on the surface of carbon ionic liquid electrode (CILE). Myoglobin (Mb) was further immobilized on the modified electrode surface. The results of ultraviolet-visible (UV-vis) and Fourier transform infrared (FT-IR) spectroscopy showed that Mb maintained its native structure without denaturation in the composite film. Direct electron transfer and the electrocatalytic properties of Mb on the electrode surface were further investigated. A pair of quasi-reversible redox peaks appeared on the cyclic voltammogram, indicating that direct electrochemistry of Mb was realized in the nanocomposite film. This could be attributed to the specific properties of TiO₂@CNF nanocomposite, including a large surface-to-volume ratio, good biocompatibility and high conductivity. Nafion/Mb/TiO₂@CNF/CILE exhibited an excellent electrochemical catalytic ability in the reduction of trichloroacetic acid, NaNO₂ and H₂O₂. All results demonstrated potential applications of TiO₂@CNF in third-generation electrochemical biosensors.

A new biosensing strategy based on a TiO₂-doped carbon nanofiber (CNF) composite modified electrode was developed.

A specific electrochemiluminescence sensor for selective and ultra-sensitive mercury(ii) detection based on dithiothreitol functionalized copper nanocluster/carbon nitride nanocomposites

A novel electrochemiluminescence sensor based on the combination of copper nanoclusters and carbon nitride nanosheets was fabricated for detecting Hg²⁺.

Dual nanoenzyme modified microelectrode based on carbon fiber coated with AuPd alloy nanoparticles decorated graphene quantum dots assembly for electrochemical detection in clinic cancer samples

The development of high-efficient technologies for cancer biomarkers detection has attracted tremendous research effort for its great clinic significance. In this work, we designed a new type of flexible and robust nanohybrid microelectrode by modifying carbon fiber with dual nanoenzyme, i.e., AuPd alloy nanoparticles (AuPd-ANPs) decorated graphene quantum dots (GQDs) assembly, and explored its practical application in electrochemical sensing system for sensitive detection of cancer biomarker hydrogen peroxide (H₂O₂) in human breast cancer cells and tissue. For the preparation of dual nanoenzyme modified microelectrode, ionic liquid was used as the electrolyte for the effective electrodeposition of GQDs on carbon fiber substrate to form a close-packed assembly under a very negative potential, then the highly dense AuPd-ANPs were uniformly decorated on GQDs assembly by electrodeposition. In virtue of the structural merits and synergistic contribution of dual nanoenzyme in enhancing the electrocatalytic activity to H₂O₂, the resultant nanohybrid microelectrode exhibited good sensing performances for electrochemical detection of H₂O₂, including a high sensitivity of 371 μA cm^-2 mM^-1, a wide linear range from 1.0 μM to 18.44 mM, a low detection limit of 500 nM (a signal-to-noise ratio of 3:1), as well as good selectivity and biocompatibility, which could be used for real-time tracking H₂O₂ released from different types of human breast cells and in situ sensitive detection of H₂O₂ in clinical breast cancer tissue.

A novel cytosensor based on Pt@Ag nanoflowers and AuNPs/Acetylene black for ultrasensitive and highly specific detection of Circulating Tumor Cells

Circulating tumor cells (CTCs), as the cellular origin of metastasis, are cancer cells that break away from a primary tumor and circulate in the peripheral blood. And they provide a wealth of information about tumor phenotype. Here, this work reported a novel ultrasensitive immunoassay protocol for the detection of CTCs by using Pt@Ag nanoflowers (Pt@AgNFs) and AuNPs/Acetylene black (AuNPs/AB) nanomaterial. In the established approach, AuNPs/AB nanomaterial was used as substrate material to increase the specific surface area and enhance the conductivity of the gold electrode. Protein G was used for oriented immobilization of capture antibody, which strongly improved the capture efficiency of MCF-7 cells. The innovatively synthesized Pt@AgNFs by our group with high specific surface area and good biocompatibility were not only as the carriers of signal antibodies (Ab₂) but also catalyzed the reduction of H₂O₂, which effectually amplified the current signal. A linear relationship between current signals and the concentrations of CTCs was obtained in the range from 20 to 1×10⁶ cells mL^-1 and the detection limit is as low as 3 cells mL^-1 on condition of acceptable stability and reproducibility. Furthermore, the as-proposed cytosensor showed excellent performance in the detection of CTCs in human blood samples. These results suggest that the proposed cytosensor will be a promising application for accurately quantitative detection of CTCs.

Metal-Organic Framework-Based Sensors for Environmental Contaminant Sensing

Increasing demand for timely and accurate environmental pollution monitoring and control requires new sensing techniques with outstanding performance, i.e., high sensitivity, high selectivity, and reliability. Metal-organic frameworks (MOFs), also known as porous coordination polymers, are a fascinating class of highly ordered crystalline coordination polymers formed by the coordination of metal ions/clusters and organic bridging linkers/ligands. Owing to their unique structures and properties, i.e., high surface area, tailorable pore size, high density of active sites, and high catalytic activity, various MOF-based sensing platforms have been reported for environmental contaminant detection including anions, heavy metal ions, organic compounds, and gases. In this review, recent progress in MOF-based environmental sensors is introduced with a focus on optical, electrochemical, and field-effect transistor sensors. The sensors have shown unique and promising performance in water and gas contaminant sensing. Moreover, by incorporation with other functional materials, MOF-based composites can greatly improve the sensor performance. The current limitations and future directions of MOF-based sensors are also discussed.

Recent Advances in Electrochemical Immunosensors

Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes), or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017.