Electrochemiluminescence Enhanced by a Non-Emissive Dual Redox Mediator.

A sulfonated tris(1-phenylpyrazolato)iridium(III) complex ([Ir(sppz)3]3-) serves as a proof-of-concept non-emissive enhancer of the widely used ECL detection system of tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)3]2+) with tri-n-propylamine (TPrA) co-reactant, acting through electrocatalysis of TPrA oxidation and efficient chemi-excitation of the luminophore. Using self-interference ECL spectroscopy, we show that the enhancer extends diffusion of the required electrogenerated precursors from the electrode surface. Previously reported enhancement through these pathways has been confounded by the inherent ECL of the enhancer, but the increase in [Ru(bpy)3]2+ ECL intensity using [Ir(sppz)3]3- was obtained without its concomitant emission. The most prominent enhancement (11-fold) occurred at low potentials associated with the 'indirect' co-reactant ECL pathway, which translated to between 2- and 6-fold enhancement when the luminophore was immobilised on microbeads as a general model for enhanced ECL assays.

Iridium(III) solvent complex-based electrogenerated chemiluminescence method for the detection of 3-methylhistidine in urine.

3-Methylhistidine (3-MeHis) is increasingly used as an indicator of muscle protein breakdown. The development of a sensitive, simple, and non-invasive method for 3-MeHis assay is important in clinical practice. Herein, a sensitive, simple, and non-invasive electrogenerated chemiluminescence (ECL) method was proposed for the quantitation of 3-MeHis in urine by using an iridium(III) solvent complex ([Ir(dfppy)2(DMSO)Cl], dfppy = 2-(2,4-difluorophenyl)pyridine, Ir-DMSO) as a signal reagent. The photoluminescence (PL) and ECL responses of Ir-DMSO to 3-MeHis were studied. The ECL intensity of Ir-DMSO was enhanced in the presence of 3-MeHis because of the coordination recognition between Ir-DMSO and the imidazole group of 3-MeHis. Based on the enhancement of ECL intensity, 3-MeHis can be sensitively detected in the range of 5 to 25 µM. The detection limit was 0.4 µM. This is the first report of an ECL method for the quantitation of 3-MeHis. Further, to investigate the feasibility of the Ir-DMSO-based ECL method in practical applications, the developed ECL method was applied for 3-MeHis assay in urine samples of 28 healthy volunteers and 2 patients. The urine samples from patients hospitalized with obesity and kidney disease and healthy individuals were distinguished by the ECL responses of Ir-DMSO. The proposed ECL method based on the coordination recognition between iridium(III) solvent complex and the imidazole group of 3-MeHis allows inexpensive, fast, non-invasive, and sensitive detection of 3-MeHis in urine, which is promising for assessing large volumes of patients for routine analysis in clinical practices.

Electrogenerated chemiluminescence from luminol-labelled microbeads triggered by in situ generation of hydrogen peroxide.

We developed a sensing strategy that mimics the bead-based electrogenerated chemiluminescence immunoassay. However, instead of the most common metal complexes, such as Ru or Ir, the luminophore is luminol. The electrogenerated chemiluminescence of luminol was promoted by in situ electrochemical generation of hydrogen peroxide at a boron-doped diamond electrode. The electrochemical production of hydrogen peroxide was achieved in a carbonate solution by an oxidation reaction, while at the same time, microbeads labelled with luminol were deposited on the electrode surface. For the first time, we proved that was possible to obtain light emission from luminol without its direct oxidation at the electrode. This new emission mechanism is obtained at higher potentials than the usual luminol electrogenerated chemiluminescence at 0.3-0.5 V, in conjunction with hydrogen peroxide production on boron-doped diamond at around 2-2.5 V (vs Ag/AgCl).

Electrochemiluminescence Microscopy.

Electrochemiluminescence (ECL) is rapidly evolving from an analytical method into an optical microscopy. The orthogonality of the electrochemical trigger and the optical readout distinguishes it from classic microscopy and electrochemical techniques, owing to its near-zero background, remarkable sensitivity, and absence of photobleaching and phototoxicity. In this minireview, we summarize the recent advances in ECL imaging technology, emphasizing original configurations which enable the imaging of biological entities and the improvement of the analytical properties by increasing the complexity and multiplexing of bioassays. Additionally, mapping the (electro)chemical reactivity in space provides valuable information on nanomaterials and facilitates deciphering ECL mechanisms for improving their performances in diagnostics and (electro)catalysis. Finally, we highlight the recent achievements in imaging at the ultimate limits of single molecules, single photons or single chemical reactions, and the current challenges to translate the ECL imaging advances to other fields such as material science, catalysis and biology.

Electrogenerated Chemiluminescence Biosensor for Quantization of Matrix Metalloproteinase-3 in Serum via Target-Induced Cleavage of Oligopeptide.

A highly sensitive and selective electrogenerated chemiluminescence (ECL) biosensor was developed for the determination of matrix metalloproteinase 3 (MMP-3) in serum via the target-induced cleavage of an oligopeptide. One ECL probe (named as Ir-peptide) was synthesized by covalently linking a new cyclometalated iridium(III) complex ([(3-pba)2Ir(bpy-COOH)](PF6)) (3-pba = 3-(2-pyridyl) benzaldehyde, bpy-COOH = 4'-methyl-2,2'-bipyridine-4-carboxylic acid) with an oligopeptide (CGVPLSLTMGKGGK). An ECL biosensor was fabricated by firstly casting Nafion and gold nanoparticles (AuNPs) on a glassy carbon electrode and then self-assembling both of the ECL probes, 6-mercapto-1-hexanol and zwitterionic peptide, on the electrode surface, from which the AuNPs could be used to amplify the ECL signal and Ir-peptide could serve as an ECL probe to detect the MMP-3. Thanks to the MMP-3-induced cleavage of the oligopeptide contributing to the decrease in ECL intensity and the amplification of the ECL signal using AuNPs, the ECL biosensor could selectively and sensitively quantify MMP-3 in the concentration range of 10-150 ng·mL-1 and with both a limit of quantification (26.7 ng·mL-1) and a limit of detection (8.0 ng·mL-1) via one-step recognition. In addition, the developed ECL biosensor showed good performance in the quantization of MMP-3 in serum samples, with a recovery of 92.6% ± 2.8%-105.6% ± 5.0%. An increased level of MMP-3 was found in the serum of rheumatoid arthritis patients compared with that of healthy people. This work provides a sensitive and selective biosensing method for the detection of MMP-3 in human serum, which is promising in the identification of patients with rheumatoid arthritis.

Chemiluminescence and electrochemiluminescence of water-soluble iridium(III) complexes containing a tetraethylene-glycol functionalised triazolylpyridine ligand.

BACKGROUND: Iridium(III) complexes, exhibiting high luminescence quantum yields and a wide range of emission colours, are promising alternatives to tris(2,2'-bipyridine)ruthenium(II) for chemiluminescence (CL) and electrochemiluminescence (ECL) detection. This emerging class of reagent, however, is limited by the poor solubility of many iridium(III) complexes in aqueous solution, and lack of understanding of their remarkably variable selectivities towards different analytes. RESULTS: Seven [Ir(C^N)2(pt-TEG)]+ complexes, exhibiting a wide range of reduction potentials and emission energies, were examined with six model analytes. For CL, cerium(IV) was used as the oxidant. The alkylamine analytes generally produced greater CL and ECL with the more readily oxidised Ir(III) complexes (C^N = piq, bt, ppy), predominantly through the 'direct' pathway requiring oxidation of both metal complex and analyte. Aniline derivatives that did not also contain secondary or tertiary alkylamines elicited CL from the less readily oxidised complexes (C^N = df-ppy-CF3, df-ppy) via energy transfer. The most difficult to oxidise complexes (C^N = df(CF3)-ppy-Me, df(CN)-ppy) gave poor responses due to the limited potential window of the solvent and inefficiency of energy transfer to their high energy excited states. Greater CL and/or ECL intensities were generally obtained for each analyte with at least one Ir(III) complex than with [Ru(bpy)3]2+; superior limits of detection for two analytes were demonstrated. SIGNIFICANCE: This exploration of CL/ECL in which the properties of luminophore, analyte and oxidant are all varied provides a new understanding of the influence of the metal-complex potentials and excited state energy on the light-producing and quenching pathways, and consequently, their distinct selectivity towards different analytes. These findings will guide the development of water-soluble Ir(III) complexes as CL and ECL reagents.

Electrochemiluminescence of a First-Row d6 Transition Metal Complex.

We report the electrochemiluminescence (ECL) of a 3d6 Cr(0) complex ([Cr(LMes)3]; λem=735 nm) with comparable photophysical properties to those of ECL-active complexes of 4d6 or 5d6 precious metal ions. The electrochemical potentials of [Cr(LMes)3] are more negative than those of [Ir(ppy)3] and render the [Cr(LMes)3]* excited state inaccessible through conventional co-reactant ECL with tri-n-propylamine or oxalate. ECL can be obtained, however, through the annihilation route in which potentials sufficient to oxidise and reduce the luminophore are alternately applied. When combined with [Ir(ppy)3] (λem=520 nm), the annihilation ECL of [Cr(LMes)3] was greatly enhanced whereas that of [Ir(ppy)3] was diminished. Under appropriate conditions, the relative intensities of the two spectrally distinct emissions can be controlled through the applied potentials. From this starting point for ECL with 3d6 metal complexes, we discuss some directions for future development.

Electrogenerated Chemiluminescence Imaging of Single-Atom Nanocatalysts.

Single-atom catalysts (SACs), distinguished by their maximum atom efficiency and precise control over the coordination and electronic properties of individual atoms, show great promise in electrocatalysis. Gaining a comprehensive understanding of the electrochemical performance of SACs requires the screening of electron transfer process at micro/nano scale. This research pioneers the use of electrogenerated chemiluminescence microscopy (ECLM) to observe the electrocatalytic reactions at individual SACs. It boasts sensitivity at the single photon level and temporal resolution down to 100 ms, enabling real-time capture of the electrochemical behavior of individual SACs during potential sweeping. Leveraging the direct correlation between ECL emission and heterogeneous electron transfer processes, we introduced photon flux density for quantitative analysis, unveiling the electrocatalytic efficiency of individual SACs. This approach systematically reveals the relationship between SACs based on different metal atoms and their peroxidase (POD)-like activity. The outcomes contribute to a fundamental understanding of SACs and pave the way for designing SACs with diverse technological and industrial applications.

Ratiometric electrogenerated chemiluminescence sensing microRNA based on electrochemically controlled release of lucigenin from silica/chitosan/lucigenin nanoparticles.

The dye-doped silica nanoparticles-based electrogenerated chemiluminescence (ECL) has been widely explored for analytical purposes due to its high sensitivity, simplicity and wide dynamic concentration range. However, only a few of dye molecules located at the near surface of nanoparticles can participate in the ECL reaction due to the poor conductivity of silica nano-matrix. In addition, the ECL signal is easy to be affected by environmental interference, which results in poor accuracy. Herein, a ratiometric ECL sensing method is established based on the electrochemically controlled release of lucigenin molecules from silica/chitosan/lucigenin composite nanoparticles (Lu/CS NPs) with the aid of sulfide ions. Firstly, H+ produced from the electrochemical oxidation of HS- ions can combine with SiO- and displace lucigenin from Lu/CS NPs. The released lucigenin molecules react with the reactive oxygen species (ROS) generated from the electroreduction of dissolved oxygen to produce the cathodic ECL signal. In addition, the excited elemental sulfur from the electrooxidation of HS- ions transfers its energy to lucigenin molecules and makes them be excited to produce energy-transfer anodic ECL signal. Based on these findings, a ratiometric ECL sensor is developed taking the anodic ECL intensity of lucigenin as a reference signal for the cathodic ECL of lucigenin. The proposed ratiometric ECL sensor has been successfully applied to the detection of let-7a with a wide linear range of 0.1-9.0 pM, a low detection limit of 28 fM, high selectivity and good reproducibility. Moreover, the developed approach was used to detect let-7a in human serum composite samples with good recoveries.

Coreactant-free strong Ru(bpy)32+ ECL at ionic liquid modified electrode and its application in sensitive detection of glucose based on resonance energy transfer.

In this work, we have realized the strong anodic ECL emission of Ru(bpy)32+ at ionic liquid (N-butylpyridinium tetrafluoroborate) modified electrode without additional coreactant. Methylene blue (MB) could accept the energy of Ru(bpy)32+ ECL to construct resonance energy transfer (ECL-RET) system, leading to the decrease of ECL signal. In the presence of glucose oxidase, hydrogen peroxide generated from the oxidation process of glucose could oxidize MB and block the ECL-RET route, resulting in the recovery of ECL signal. As a consequence, the designed sensor showed outstanding performance for "signal-on" detection of glucose in the concentration range of 10 µM to 1 mM, and the detection limit was determined as 1.75 µM. Importantly, this study revealed new roles of ILs in the fabrication of coreactant-free ECL sensing, which might open up a promising route for the potential design and implement in clinical analysis.

Electrochemiluminescence bioassay with anti-fouling ability for determination of matrix metalloproteinase 9 secreted from living cells under external stimulation.

An electrochemiluminescence (ECL) bioassay with high sensitivity and anti-fouling ability was developed for determination of matrix metalloproteinase 9 (MMP-9) secreted from living cells under external stimulation. A peptide with sequence of CLGRMGLPGK and a new cyclometalated iridium(III) complex bearing carboxyl group, (pq)2Ir(dcbpy) (pq = 2-phenylquinoline, dcbpy = 2,2'-bipyridyl-4,4'-dicarboxyli acid, abbreviated as Ir) were employed as molecular recognition substrate and ECL emitter, respectively. The peptide was labelled with the Ir to form Ir-peptide as ECL probe. Ir-peptide was self-assembled onto Nafion and gold nanoparticles (AuNPs) modified glassy carbon electrode (AuNPs/Nafion/GCE) and then both of 6-mercapto-1-hexanol (MCH) and zwitterionic peptide as blocking reagents were co-assembled on Ir-peptide/AuNPs/Nafion/GCE to form an anti-fouling ECL peptide-based biosensor. MMP-9 can be quantified in the range 1.0-50 ng·mL-1 with a detection limit of 0.50 ng·mL-1 based on the decreased ECL intensity. Relative standard derivation was 2.3% for six fabricated anti-fouling ECL peptide-based biosensors after reaction with 50 ng·mL-1 MMP-9. The anti-fouling ECL peptide-based biosensor can be used to monitor MMP-9 secreted from living cells under external stimulation. 96.0%-108.0% of recoveries were obtained in 60-diluted cell culture media. This study demonstrates that the ECL biosensor by the combination of iridium(III) complex-based sensitive ECL method and the anti-fouling interface provides a promising way for the determination of MMP-9 in biological sample, which is viable in clinical diagnosis and point-of-care test of protease.

Regulating highly photoelectrochemical activity of Zr-based mixed-linker metal-organic frameworks toward sensitive electrogenerated chemiluminescence sensing of α-glucosidase.

The conductivity and emission efficiency of metal-organic frameworks (MOFs) remain challenging factors that limit their electrogenerated chemiluminescence (ECL) sensing applications. Herein, we report a facile approach to address these challenges by integrating an electroactive linker (H2-TCPP) with an ECL active electrogenerated chemiluminescence linker (H4-TBAPy) to construct a highly photoelectrochemical active mixed-linker MOFs (ML-MOFs). ECL results revealed a remarkable 15.4-fold enhancement for the top-performing ML-MOFs (M6-MOFs), surpassing the single linker MOFs. In addition, M6-MOFs also exhibit a remarkable 73-fold enhancement in ECL efficiency compared to commercial Ru (bpy)32+. This improvement should be attributed to the synergistic effects resulting from the combination of two linkers. Furthermore, M6-MOFs are found to be served as a model ECLphore for sensitive and selective detection of α-glucosidase for the first time with good potential practicability in human serum samples. This work represents a promising direction to guide for designing good conductivity and high ECL efficiency MOFs in terms of linker functionalization and thus bandgap modulation for advancing their ECL sensing applications.

Photoinduced Electrogenerated Chemiluminescence Imaging of Plasmonic Photoelectrochemistry at Single Nanocatalysts.

In this study, we proposed a novel imaging technique, photoinduced electrogenerated chemiluminescence microscopy (PECLM), to monitor redox reactions driven by hot carriers on single gold nanoparticles (AuNPs) on TiO2. Under laser irradiation, plasmon-generated hot carriers were separated by an electric field, leaving hot holes on the surface of AuNPs to drive ECL reactions. PECL intensity was highly sensitive to the number of hot carriers. Through quantitative image analysis, we found that PECL density on individual AuNPs decreased significantly with an increase in particle diameter, indicating that particle size has a significant impact on photoelectrochemical conversion efficiency. For the first time, we verified the feasibility of PECLM in mapping the catalytic activity of single photocatalysts. PECLM opens a new prospect for the in situ imaging of photocatalysis in a high-throughput way, which not only facilitates the optimization of plasmonic photocatalysts but also contributes to the dynamic study of photocatalytic processes on micro/nanointerfaces.

Cadmium ions mediated turn-on electrogenerated chemiluminescence of ZnS nanoparticles for highly selective cadmium detection in seafood.

Cd2+ is one of the most toxic heavy metal ions that can be easily accumulated in human body via food chain. Thus, the onsite detection of Cd2+ in food is very important. However, present methods for Cd2+ detection either require the use of large equipment, or suffer from the severe interference from other analogical metal ions. This work establishes a facile Cd2+ mediated turn-on ECL method for highly selective detection of Cd2+ via cation exchanging with the nontoxic ZnS nanoparticles, owing to the unique surface-state ECL properties of CdS nanomaterials. The linear range of the calibration curve is from 7.0 × 10-8 to 1.0 × 10-6 M, while other analogical metal ions do not interfere, facilitating the selective detection of Cd2+ in oyster samples. The result agrees well with that obtained using atomic emission spectroscopy, indicating the potential for wider application of this approach.

Performance enhancement of electrochemiluminescence magnetic microbiosensors by using double magnetic field actuation for cancer biomarkers and exosomes.

This work reports the performance enhancement strategies on magnetic beads (MBs)-based electrochemiluminescence (ECL) platforms by using double magnetic field actuation of the ECL magnetic microbiosensors (MMbiosensors) for highly sensitive determination of cancer biomarker and exosomes. To obtain the high sensitivity and reproducibility of the ECL MMbiosensors, a series of strategies have been developed including replacing a conventional photomultiplier tube (PMT) with a diamagnetic PMT, replacing the stacked ring-disc magnets with circular-disc magnets lain-in glassy carbon electrode, adding a pre-concentration process of MBs using external magnet actuation. For fundamental research, the ECL MBs taken as the substitute of ECL MMbiosensors were prepared by binding biotinylated DNA tagged with Ru(bpy)32+ derivative (Ru1) to streptavidin-coated MB(MB@SA) were which showed that the developed strategies can enhance 45-fold sensitivity. Importantly, the developed MBs-based ECL platform was estimated by determination of prostate specific antigen (PSA) and exosomes. For PSA, MB@SA•biotin-Ab1(PSA) was taken as the capture probe and Ru1-labeled Ab2 (PSA) was done as ECL probe, while for exosomes, MB@SA•biotin-aptamer (CD63) was taken as the capture probe and Ru1-labeled Ab (CD9) was done as the ECL probe. The experiment results showed that the developed strategies can enhance 33-fold sensitivity of ECL MMbiosensors for PSA and exosomes. The detection limit is 0.28 ng mL-1 for PSA and 4.9 × 102 particle mL-1 for exosomes. This work demonstrated that a series of proposed magnetic field actuation strategies greatly increase the sensitivity of the ECL MMbiosensors. The developed strategies can be expanded to MBs-based ECL and electrochemical biosensors for clinical analysis with greater sensitivity.

Washing-free electrogenerated chemiluminescence magnetic microbiosensors based on target assistant proximity hybridization for multiple protein biomarkers.

This work reports washing-free electrogenerated chemiluminescence (ECL) magnetic microbiosensors based on target assistant proximity hybridization (TAPH) for multiple protein biomarkers for the first time. As a principle-of-proof, alpha-fetoprotein (AFP) was chosen as a model analyte, and biotin-DNA1 bound streptavidin-coated magnetic microbeads (MMB@SA⋅biotin-DNA1) were designed as the universal capture MMB, while the corresponding two antibodies tagged with DNA2 or DNA3 were utilized as hybrid recognition probes, and ruthenium complex-tagged DNA4-10A was designed as a universal ECL signal probe. When the capture MMB was added into the mixture solution (containing the analyte, hybrid recognition probes, signal probe and tri-n-propylamine), biocomplexes were formed on the MMB. After the resulting MMB was efficiently brought to the surface of a magnetic glassy carbon electrode (MGCE), ECL measurement was performed without a washing step, resulting in an increase in the ECL intensity. A model for ECL measuring the second-order rate constants of hybridization reactions on MMB was derived. It was found that the rate constants for hybridization reactions on MMB in rotating mode are 1.6-fold higher than those in shaking mode, and a suitable DNA length of the signal probe can improve the signal-to-noise ratio. The washing-free ECL method was developed for the determination of AFP with a much lower detection limit (LOD) of 0.04 ng mL-1. The developed flexible strategy has been extended to determine D-dimer with an LOD of 0.1 ng mL-1 and myoglobinglobin with an LOD of 1.1 ng mL-1. This work demonstrated that the proposed strategy of ECL TAPH on MMB at MGCE is a washing-free and flexible promising strategy, and can be extended to qualify other multiple protein biomarkers in real clinical assays.

Ultrasound-pretreatment combined with Ti3C2-TiO2-AuNPs enhancing the electrogenerated chemiluminescence of the air-saturated luminol for exosomes detection.

It is still a great challenge to develop effective strategies to improve the low electrogenerated chemiluminescence (ECL) of air-saturated luminol. Herein, the synergistic effects of Ti3C2-TiO2-AuNPs nano hybrid and high-intensity focused ultrasound pretreatment (ultrasound-pretreatment) were used to significantly improve the ECL emission of the air-saturated luminol, and the mechanism was proposed. The ultrasound-pretreatment as a green method with the cavitation effect could form O2-• and H2O2 in situ as an initiator. TiO2 and Au nanoparticles (AuNPs) were in situ decorated on the Ti3C2 surface to form Ti3C2-TiO2-AuNPs, and it was proved as a highly efficient booster which could catalyze and aggregate H2O2 to the O2-•. The utilization rate of intermediates has been greatly improved. Exosomes as model targets can be sensitively detected by the ECL sensor. The detection limit was 195 particles µL-1. The detection results of exosomes in actual samples are satisfactory. We believe that the ultrasound-pretreatment strategy could be extended to the sensitive detection in the biological sample.

Iridium(III) solvent complex-based electrogenerated chemiluminescence and photoluminescence sensor array for the discrimination of bases in oligonucleotides.

Development of rapid and sensitive method for the discrimination of bases in oligonucleotides is of great importance in clinical diagnosis. Here, we demonstrate the first case of single iridium(III) solvent complex-based electrogenerated chemiluminescence (ECL) and photoluminescence (PL) sensor array for the discrimination of bases in oligonucleotides. One iridium (III) solvent complex ([Ir(ppy)2(DMSO)Cl], ppy = 2-phenylpyridine, probe 1) was designed as both ECL and PL probe while five bases (guanine, adenine, cytosine, thymine and uracil) were chosen as analytes. Two-element sensor array was built for the discrimination of five bases based on the fingerprint response of probe 1 to bases via coordination interactions. The combination of unique ECL and PL variations with principal component analysis was applied for the quantitative analysis of five bases in a linear range of 1.0 µM-10 µM and for the effective discrimination of individual base, the mixture of bases and oligonucleotides. Moreover, the sensor array was successfully applied to discriminate different mismatched ss-DNAs from HIV gene (a fully-matched ss-DNA), even at single-base difference. This work demonstrates that the sensor array using single iridium (III) solvent complex is a promising approach for the discrimination of bases with good sensitivity and simpleness in clinical diagnosis.

Sensitive and selective electrogenerated chemiluminescence aptasensing method for the determination of dopamine based on target-induced conformational displacement.

Dopamine (DA) is an important neurotransmitter associated with many diseases. It is very significant to detect DA with high sensitivity and good selectivity. Here, a sensitive and selective electrogenerated chemiluminescence (ECL) aptasensing method was developed for the determination of DA based on target-induced conformational displacement. An anti-DA specific aptamer spliting into two ss-DNA (S1 and S2) was used as molecular recognition elements while an ss-DNA labeled with ferrocene (Fc-CS1, complementary to S1) was used as quenching probe. An ECL platform was prepared by dropping the mixture of Nafion, gold nanoparticles (AuNPs) and Ru(bpy)32+ onto glassy carbon electrode (GCE). After hybridization of S1 and Fc-CS1, ds-DNA (S1-CS1-Fc) was self-assembled onto the ECL platform to form an ECL aptasensing platform. In the presence of DA and S2, a S1-S2-DA complex was formed and then Fc-CS1 was released from the electrode surface, resulting in an increase of ECL intensity. DA can be sensitively detected in the range of 1.0 × 10-9 M to 5 × 10-8 M with a lower detection limit of 0.32 nM. This is first report of ECL aptasensing method for the determination of DA based on target-induced conformational displacement. The proposed ECL aptasensing method, exploiting both the aptamer recognition and ECL detection, allows direct detection of DA in diluted serum samples with high sensitivity and good selectivity, which may be further applicable in other neurochemicals assay and biomedical research.

Toward Next-Generation Mobile Diagnostics: Near-Field Communication-Powered Electrochemiluminescent Detection.

Mobile phones have been used in combination with point of care (PoC) devices for over a decade now. However, their use seems restricted to the detection of sensing events using the video and camera functions. In contrast, the complementary ability to use mobile phones to power such PoC devices has been largely unexplored. This work demonstrates the proof-of-principle that a smartphone can be used to both power and analyze an electrochemiluminescence (ECL) detection system. A printed device is presented featuring an electrochemical cell connected in series to a rectenna that is able to use the Near Field Communication (NFC, 13.56 MHz) signal to provide the energy needed to generate ECL from Ru(bpy)32+/tri-n-propylamine. The emitted light, the intensity of which is directly proportional to the concentration of the ruthenium complex, can then be captured by the mobile phone camera and analyzed. This work presents the fabrication and the electrical and electrochemical characterization of the device. Effective voltages ranging from 0.90 to 4.50 V have been recorded, depending on the coupling between emitter and receiver, which translate into working electrode potentials ranging from 0.76 up to 1.79 V vs Ag. Detection and quantification limits of 0.64 and 1.52 µM, respectively, have been achieved for Ru(bpy)32+, and linear ranges up to 0.1 mM (red channel) and no less than 1.0 mM (green channel) have been found.