ABSTRACT
An efficient electrochemiluminescence (ECL) emitter, Ir(ppy)3-based molecules has recently been reported to exhibit aggregation-induced electrochemiluminescence (AIECL) phenomenon. However, it remains a significant challenge to control the aggregation states of these molecules and achieve uniform aggregates with intense ECL emission. In this work, a biosensor was developed to detect microcystin-LR (MC-LR) based on Ir(ppy)3-functionalized zeolitic imidazolate framework-8 (Ir-ZIF-8) as the ECL emitter and the trans-cleavage activity of CRISPR-Cas12a as the methodological strategy. The Ir-ZIF-8, a functional metal-organic framework (MOF), exhibited the AIECL phenomenon via the spatial domain-limiting effect of encapsulating Ir(ppy)3 into the mesopores of ZIF-8, while the porosity and highly ordered topological structure of ZIF-8 effectively limited the molecular motion of Ir(ppy)3. CRISPR-Cas12a was employed to indiscriminately cleave double-stranded DNA decorated with carboxy tetramethylrhodamine (TAMRA), which quenched the ECL signal of Ir-ZIF-8 by resonance energy transfer and then separated the quencher from Ir-ZIF-8 to reactivate the signal. The concentration of MC-LR was designed to correlate with both the quencher amount and the activity of Cas12a. Then, two linear regression equations for MC-LR detection were constructed to improve the accuracy of the biosensor, and the constructed biosensor showed remarkable reproducibility, stability, and selectivity. The accurate detection of MC-LR with limits of detection of 1.2 and 5.9 pg/mL was made possible by the high quenching efficiency of TAMRA and the effective cutting ability of the editable CRISPR-Cas12a system.
Subject(s)
Biosensing Techniques , CRISPR-Cas Systems , Electrochemical Techniques , Luminescent Measurements , Marine Toxins , Microcystins , Microcystins/analysis , Microcystins/chemistry , Marine Toxins/chemistry , CRISPR-Cas Systems/genetics , Biosensing Techniques/methods , Zeolites/chemistry , Metal-Organic Frameworks/chemistry , Imidazoles/chemistry , Limit of Detection , CRISPR-Associated Proteins/metabolism , CRISPR-Associated Proteins/chemistryABSTRACT
The sensitivity and specificity of electrochemiluminescence (ECL)-based biosensor directly rely on the property of luminophor, the type of sensing carriers and the effectiveness of signal amplification used in the sensor design, which poses a major challenge to manage these elements simultaneously. In this work, an aggregation-induced electrochemiluminescence (AIECL) microfluidic sensing chip using 4',4â³,4â´,4â´'-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid (TPE)-derived hafnium-based metal-organic framework (Hf-MOF) as emitter was developed. An easily overlooked marine pollutant, okadaic acid (OA) with different concentrations ranging from 5.00 ng/mL to 1.50 × 104 ng/mL at the electrode is visualized imaging benefit from high luminescence efficiency of Hf-MOF coupled the rolling circle amplification strategy assisted by trans-cleavage activity of CRISPR/Cas12a. These highlights will solve the long-lasting task in the accurate analysis of small molecule pollutants, which can be able to provide more worthy reference solution about construction of novel ECL luminophor and signal extraction of low-abundance disease-related biomarkers.
Subject(s)
Biosensing Techniques , Electrochemical Techniques , Luminescent Measurements , Metal-Organic Frameworks , Okadaic Acid , Biosensing Techniques/methods , Biosensing Techniques/instrumentation , Luminescent Measurements/methods , Luminescent Measurements/instrumentation , Electrochemical Techniques/methods , Okadaic Acid/analysis , Metal-Organic Frameworks/chemistry , Lab-On-A-Chip Devices , Limit of Detection , Equipment DesignABSTRACT
In this letter, a sensitive microfluidic immunosensor chip was developed using tetrakis(4-aminophenyl)ethene (TPE)-derived covalent organic frameworks (T-COF) as aggregation-induced electrochemiluminescence (AIECL) emitters and nanobodies as efficient immune recognition units for the detection of thymic stromal lymphopoietin (TSLP), a novel target of asthma. The internal rotation and vibration of TPE molecules were constrained within the framework structure, forcing nonradiative relaxation to convert into pronounced radiative transitions. A camel-derived nanobody exhibited superior specificity, higher residual activity and epitope recognition postcuring compared to monoclonal antibodies. Benefiting from the affinity between silver ions (Ag+) and cytosine (C), a double-stranded DNA (dsDNA) embedded with Ag+ was modified onto the surface of TSLP. A positive correlation was obtained between the TSLP concentration (1.00 pg/mL to 4.00 ng/mL) and ECL intensity, as Ag+ was confirmed to be an excellent accelerator of the generation of free radical species. We propose that utilizing COF to constrain luminescent molecules and trigger the AIECL phenomenon is another promising method for preparing signal tags to detect low-abundance disease-related markers.