Analysis & sensing最新文献

Editor in Chief Jonathan Faiz looks back at the developments in Analysis & Sensing in 2022, and introduces our new Commissioning Editors.

We report here a colorimetric carbon dioxide (CO₂) optode sensor with a polypropylene microporous membrane on top of a thin layer (30 μm) of polyurethane hydrogel. The diffusion of CO₂ across the polypropylene membrane induced pH changes in the hydrogel containing a lipophilic indicator, a cation exchanger, and a cationic amine. The ratio of the indicator and the cation exchanger was successfully utilized to adjust the sensitivity of the CO₂ response. Increasing the relative amount of the cation exchanger made the sensor much more sensitive to CO₂ in the lower concentration range. Moreover, the carbarmic formation reaction between the primary amine and CO₂ was investigated. The results indicated a very small contribution of carbarmic formation to the overall pH change. With a detection limit of 0.014 % for the CO₂ partial pressure, the sensor was successful applied to monitor CO₂ evolution during yeast catalyzed flour fermentation.

Chemiluminescence (CL) provides ideal conditions for point-of-care testing (POCT) with wide dynamic ranges, superior sensitivities, and detection simplicity. It has not arrived routinely in the POCT field due to naturally low quantum yields of typical probes and the lack of sensitive low-cost detection devices. Here, we developed a universal microfluidic paper-based analytical device (μPAD) using l-lactate as model analyte. We demonstrate that a smartphone camera can compete with a scientific CCD camera as performance benchmark when using the strong CL emitter, m-carboxy luminol, resulting in extraordinary signal-to-noise ratios of 67. The μPAD provides CV<10 %, stability at room temperature for≥3 months and simple processing. Furthermore, the μPAD enables the detection of picomoles of the luminophore providing additional design flexibility. Thus, this new CL-μPAD is available for translating the many CL standard analytical assays performed in microtiter plates, microarrays or other more complex detection strategies to the POC.

Catalytic hairpin assembly (CHA), as an enzyme-free isotheral nucleic acid amplification method, can easily cooperate with other amplification procedures to improve the sensitivity and accuracy of detection. Herein, we constructed a cascaded CHA sensing platform for breast cancer biomarker detection. Introducing a short double nucleic acid stand avoids the product of CHA1 to directly trigger the CHA2 reaction, which simplifies the design of the CHA hairpins. Compared with the single CHA2 reaction, the cascaded CHA biosensor activated by microRNA-155 holds nearly 10 times the amplification efficiency with detection limit down to 47.4 pM and quantifies the target in the range from 50 pM to 200 nM. Besides, the magnetic bead-confined CHA2 taking 3D DNA walking as the display form contributes to decreasing the environmental interference. As expected, the strategy sensitively distinguishes expression levels of microRNA-155 in different cell lines and cancer patients, which are consistent with the results of traditional qRT-PCR method. More importantly, simply adjusting the microRNA recognition sequence of CHA1 can extend the cascaded CHA platform to a wider detection range. Therefore, the robustness and efficiency of the approach enable the potential applications for detection of microRNA and early clinical disease diagnosis.

The cover feature image shows a fast-responding gating system by using horseradish peroxidase (HRP)-loaded functional RNA superstructures (HRP@3D RNA). The specificity of RNA aptamer-ligand interaction serves as a triggered manner to release the loaded HRP from HRP@3D RNA. Based on this, a disposable origami paper-based analytical device (doPAD) was developed for tetracycline (TC) detection. More information can be found in the Research Article by Meng Liu and co-workers.

Invited for this month′s cover is the collaborating groups of Prof. Sho Hideshima at Tokyo City University, Prof. Tetsuya Osaka at Waseda University, and Prof. Hiroaki Tateno at National Institute of Advanced Industrial Science and Technology, Japan. The cover picture shows a semiconductor-based biosensor with potential to detect the presence of a specific biomarker of human induced pluripotent stem cell (hiPSCs) in a culture medium. More information can be found in the Research Article by S. Hideshima, T. Osaka, and co-workers.

The cover picture represents selective visualization of hydrogen polysulfides (H₂S_n, n≥2) over other RSS, ROS and RNS by a fluorogenic reaction of 3′-O-(2-nitrobenzenesulfonyl)fluorescein, chosen as a practical H₂S_n probe from the candidate pool of 2- or 4-nitrobenzenesulfonylated fluorescein derivatives that were evaluated. This fluorogenic response occurred by straightforward one-step deprotection of the probe with H₂S_n in a selective and sensitive manner. Cover design by Yuka Shinohara. More information can be found in the Research Article by K. Tsukamoto, H. Maeda, and co-workers.

Invited for this month's cover is the group of Prof. Hatsuo Maeda at Hyogo Medical University, Japan. The cover picture features selective visualization of hydrogen polysulfides (H₂S_n, n ≥ 2) over other related species through a fluorogenic reaction of 3′-O-(2-nitrobenzenesulfonyl)fluorescein, that was screened as the best practical H₂S_n probe among 2- or 4-nitrobenzenesulfonylated fluorescein derivatives. More information can be found in the Research Article by K. Tsukamoto, H. Maeda, and co-workers.

Many DNA aptamers have been reported to target the spike protein (S-protein) of SARS-CoV-2. These aptamers display different affinities or recognize different epitopes of the S-protein. We conducted a comparative study of 9 DNA aptamers for binding to several variants of the S-protein and pseudoviruses using the same testing methods, including dot-blot assays and enzyme-linked aptamer binding assays, to evaluate their affinity ranking and analytical utility. Moreover, the binding sites of these aptamers on the S-protein were examined using aptamer competition assays to understand the effect of S-protein mutations on aptamer affinity and the degree of overlapping of the binding sites by these aptamers.

The cover feature image shows electrochemical sensing using single-atom materials (SAMs) featuring isolated metal sites embedded inside inorganic or organic supports. Thanks to the well-defined active sites, SAMs have demonstrated expectational performance. The current research progress of metal-inorganic/organic SAMs is discussed, providing an introductive outline of the rational sensor design toward higher sensitivity, selectivity, and stability. Cover design by Weiran Zheng. More information can be found in the Review by Weiran Zheng.