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Targeted imaging is playing an increasingly important role in the early detection and precise diagnosis of cancer. This need has motivated research into sensory nanomaterials that can be constructed into imaging agents to serve as biosensors. Graphene quantum dots (GQDs) as a valuable nanoprobe show great potential for use in two-photon biological imaging. However, most as-prepared GQDs exhibit a low two-photon absorption cross-section, narrow spectral coverage, and "one-to-one" signal conversion mode, which greatly hamper their wide application in sensitive early-stage cancer detection. Herein, a versatile strategy has been employed to fabricate an aptamer Sgc8c-functionalized hybrid as a proof-of-concept of the signal amplification strategy for targeted cancer imaging. In this study, GQDs with two-photon imaging performance, and silica nanoparticles (SiO2 NPs) as nanocarriers to provide amplified recognition events by high loading of GQD signal tags, were adopted to construct a two-photon hybrid-based signal amplification strategy. Thus, the obtained hybrid (denoted SiO2@GQDs) enabled extremely strong fluorescence with a quantum yield up to 0.49, excellent photostability and biocompatibility, and enhanced bright two-photon fluorescence up to 2.7 times that of bare GQDs (excitation at 760 nm; emission at 512 nm). Moreover, further modification with aptamer Sgc8c showed little disruption to the structure of the SiO2@GQDs-hybrid and the corresponding two-photon emission. Hence, SiO2@GQDs–Sgc8c showed specific responses to target cells. Moreover, it could be used as a signal-amplifying two-photon nanoprobe for targeted cancer imaging with high specificity and great efficiency, which exhibits a distinct green fluorescence compared to that of GQDs–Sgc8c or SiO2@GQDs. This signal amplification strategy holds great potential for the accurate early diagnosis of tumors and offers new tools for the detection a wide variety of analytes in clinical application. [ABSTRACT FROM AUTHOR]

To realize early fire identification in cotton harvesting operations, a mid-infrared carbon monoxide (CO) sensor system was developed. To match the broadband light source with a 15° divergence angle, a multipass gas cell (MPGC) with an effective path length of 180 cm was designed to improve sensor sensitivity, leading to a limit of detection (LoD) of 0.83 parts-per-million by volume (ppmv). A damping module with springs at the bottom and front/back sides was fabricated, which can effectively reduce the vibration intensity by >80%. The sensor system can operate normally from −40 °C to 85 °C by stabilizing the temperature of the optical module through heating or cooling as well as using automotive electronic components. An adaptive early fire identification algorithm based on a dual-parameter threshold alarming method was proposed to avoid false and missing alarms. Field deployments on a harvester verified the good practicability of the sensor system. [ABSTRACT FROM AUTHOR]

Effective methods are required to quantify the organochlorine pesticide procymidone due to its potentially harmful effects toward human health and the environment. Here, hydrophilic hollow imprinted microspheres were prepared via a simple method as fluorescent sensors (@MIH-prm) for the sensitive and selective detection of PRM in ginseng. A new method of adsorption efficiency evaluation for @MIH-prm was subsequently introduced (EBS%), the effective binding site, which provided a comprehensive evaluation of the performance compared with conventional methods. The results showed that @MIH-prm could detect PRM in filtered and diluted ginseng juice with high sensitivity (LOD, 0.569 nM) and a rapid detection rate (quantitative detection of PRM within 18 min). Good selectivity was observed in the presence of combinations of different pesticides, and the adsorption of PRM could be described by the pseudo-second-order kinetic model. PRM concentrations exhibited good linearity over 1–40 nM, and the accuracy (recovery rates, 99.2 to 103.1%) and precision (RSD at 1.0 × 10−9 M, 3.14%) indicated that @MIH-prm could be used for the quantitative analysis of PRM in complex matrices. Hence, @MIH-prm has good application potential in pollution control monitoring and enforcement. [ABSTRACT FROM AUTHOR]