Although great headway has been made in DNAzyme-based detection of Pb 2+ , its adaptability, sensitivity, and accessibility in complex media still need to be improved. For this, we introduce new ways to surmount these hurdles. First, a spherical nucleic acid (SNA) fluorescence probe (Au nanoparticles-DNAzyme probe) is utilized to specifically identify Pb 2+ and its suitability for precise detection of Pb 2+ in complex samples due to its excellent nuclease resistance. Second, the sensitivity of Pb 2+ detection is greatly enhanced via the use of a clustered regularly interspaced short palindromic repeats-Cas12a with target recognition accuracy to amplify the fluorescent signal upon the trans cleavage of the SNA (signal probe), and the limit of detection reaches as low as 86 fM. Third, we boost the fluorescence on photonic crystal chips with a bionic periodic arrangement by employing a straightforward detection device (smartphone and portable UV lamp) to achieve on-site detection of Pb 2+ with the limit of detection as low as 24 pM. Based on the abovementioned efforts, the modified Pb 2+ fluorescence sensor has the advantages of higher sensitivity, better specificity, accessibility, less sample consumption, and so forth. Moreover, it can be applied to accurately detect Pb 2+ in complex biological or environmental samples, which is of great promise for widespread applications.

The detection of hydrogen sulfide (H 2 S), the third gas signaling molecule, is a promising strategy for identifying the occurrence of certain diseases. However, the conventional single-or dual-signal detection can introduce false-positive or false-negative results, which ultimately decreases the diagnostic accuracy. To address this limitation, we developed a luminescent, photothermal, and electrochemical triple-signal detection platform by optically trapping the synthetic highly doped upconversion coupled SiO 2 microbeads coated with metal−organic frameworks H-UCNP-SiO 2 @HKUST-1 (H-USH) to detect the concentration of H 2 S. The H-USH was first synthesized and proved to have stable structure and excellent luminescent, photothermal, and electrochemical properties. Under 980 nm optical trapping and 808 nm irradiation, H-USH showed great detection linearity, a low limit of detection, and high specificity for H 2 S quantification via triple-signal detection. Moreover, H-USH was captured by optical tweezers to realize quantitative detection of H 2 S content in serum of acute pancreatitis and spontaneously hypertensive rats. Finally, by analyzing the receiver operating characteristic (ROC) curve, we concluded that triple-signal detection of H 2 S was more accurate than single-or dual-signal detection, which overcame the problem of false-negative/ positive results in the detection of H 2 S in actual serum samples.