Interfacial Assembly of Ti3 C2 Tx /ZnIn2 S4 Heterojunction for High-Performance Photodetectors

Aptamer-Modified Ti3C2Tx MXene Fluorescent Nanoprobe for Monitoring ATP and GTP during a Mild-Photothermal-Activated Nucleolar Stress Process in Living Cells

Understanding the molecular energy metabolism of single cells in the nucleolus stress response induced by mild-photothermal therapy (mPTT) is of great importance for investigating the photothermal lethal mechanism. Herein, we successfully fabricated a "turn-on"-type fluorescent nanoprobe based on the fluorescently labeled aptamers (FAM-ATP-apt and Cy3-GTP-apt) and Ti3C2TX MXene. When the adapters on the nanoprobes bonded to intracellular ATP and GTP, the fluorescence of the nanoprobes was restored. We used the nanoprobes to monitor the variation of ATP and GTP contents in individual tumor cells and normal cells during the mPTT. Interestingly, we found that NPM1 translocated from the nucleolus to the nucleoplasm in MCF-7 cancer cells within 12 min of mPTT laser irradiation, which did not occur in normal MCF-10A cells. However, the content changes of ATP and GTP in tumor cells during the mPTT treatment were significantly higher than that of normal cells. The developed Ti3C2Tx-ATP/GTP nanoprobe enables simultaneous imaging of ATP and GTP in single living cells for bioimaging and molecular detection applications.

Photo-electrochemical sensor based on BiOI/ZnIn2S4 heterojunction for detecting hydrogen peroxide and dopamine

Photoelectrochemical (PEC) detection as a potential development strategy for hydrogen peroxide and dopamine sensors has received extensive attentions. Herein, BiOI/ZnIn2S4-X (X = n (BiOI)/n(ZnIn2S4)) heterojunction was synthesized using various molar ratios via a two-step method. A series of characterization techniques were employed to analyze the composition, surface structure, valence state, and optical properties of BiOI/ZnIn2S4-X. The results show that BiOI/ZnIn2S4-X perform significantly better than both BiOI and ZnIn2S4. Furthermore, BiOI/ZnIn2S4-9% exhibits superior visible light absorption capacity and photocurrent response among all of the BiOI/ZnIn2S4-X tested. Therefore, a PEC sensor was developed using BiOI/ZnIn2S4-9% for the detection of hydrogen peroxide and dopamine. The linear detection range for hydrogen peroxide spans from to 1 ~ 40,000 µM, with the LOD of 0.036 µM (S/N = 3). For dopamine, the corresponding values are 2 ~ 250 µM for the linear detection range, and 0.017 μM for the LOD, respectively. The sensor exhibits demonstrates excellent stability, reproducibility and resistance to interference, enabling the detection of real samples and thus holds promising application potential.

Chemical Intercalation of Layered Materials: From Structure Tailoring to Applications

The intercalation of layered materials offers a flexible approach for tailoring their structures and generating unexpected properties. This review provides perspectives on the chemical intercalation of layered materials, including graphite/graphene, transition metal dichalcogenides, MXenes, and some particular materials. The characteristics of the different intercalation methods and their chemical mechanisms are discussed. The influence of intercalation on the structural changes of the host materials and the structural change how to affect the intrinsic properties of the intercalation compounds are discussed. Furthermore, a perspective on the applications of intercalation compounds in fields such as energy conversion and storage, catalysis, smart devices, biomedical applications, and environmental remediation is provided. Finally, brief insights into the challenges and future opportunities for the chemical intercalation of layered materials are provided.

Room-Temperature High-Performance Photodetector and Phototransistor Based on PdSe2/ZnIn2S4 Alloy Heterojunctions

Various semiconductor devices have been developed based on 2D heterojunction materials owing to their distinctive optoelectronic properties. However, to achieve efficient charge transfer at their interface remains a major challenge. Herein, an alloy heterojunction concept is proposed. The sulfur vacancies in ZnIn2S4 are filled with selenium atoms of PdSe2. This chemically bonded heterojunction can significantly enhance the separation of photocarriers, providing notable advantages in the field of photoelectric conversion. As a demonstration, a two-terminal photodetector based on the PdSe2/ZnIn2S4 heterojunction materials is fabricated. The photodetector exhibits stable operation in ambient conditions, showcasing superior performance in terms of large photocurrent, high responsivity (48.8 mA W-1) and detectivity (1.98 × 1011 Jones). To further validate the excellent optoelectronic performance of the heterojunction, a tri-terminal phototransistor is also fabricated. Benefiting from gate voltage modulation, the photocurrent is amplified to milliampere level, and the responsivity is increased to 229.14 mA W-1. These findings collectively demonstrate the significant potential of the chemically bonded PdSe2/ZnIn2S4 alloy heterojunction for future optoelectronic applications.

Sandwiched WS2/MoTe2/WS2 Heterostructure with a Completely Depleted Interlayer for a Photodetector with Outstanding Detectivity

Photodetectors based on two-dimensional van der Waals (2D vdW) heterostructures with high detectivity and rapid response have emerged as promising candidates for next-generation imaging applications. However, the practical application of currently studied 2D vdW heterostructures faces challenges related to insufficient light absorption and inadequate separation of photocarriers. To address these challenges, we present a sandwiched WS2/MoTe2/WS2 heterostructure with a completely depleted interlayer, integrated on a mirror electrode, for a highly efficient photodetector. This well-designed structure enhances light-matter interactions while facilitating effective separation and rapid collection of photocarriers. The resulting photodetector exhibits a broadband photoresponse spanning from deep ultraviolet to near-infrared wavelengths. When operated in self-powered mode, the device demonstrates an exceptional response speed of 22/34 μs, along with an impressive detectivity of 8.27 × 1010 Jones under 635 nm illumination. Additionally, by applying a bias voltage of -1 V, the detectivity can be further increased to 1.49 × 1012 Jones, while still maintaining a rapid response speed of 180/190 μs. Leveraging these outstanding performance metrics, high-resolution visible-near-infrared light imaging has been successfully demonstrated using this device. Our findings provide valuable insights into the optimization of device architecture for diverse photoelectric applications.

A wearable electrostimulation-augmented ionic-gel photothermal patch doped with MXene for skin tumor treatment

A wearable biological patch capable of producing multiple responses to light and electricity without interfering with daily activities is highly desired for skin cancer treatment, but remains a key challenge. Herein, the skin-mountable electrostimulation-augmented photothermal patch (eT-patch) comprising transparent ionic gel with MXene (Ti3C2Tx) doping is developed and applied for the treatment of melanoma under photostimulation at 0.5 W/cm2. The eT-patch designed has superior photothermal and electrical characteristics owing to ionic gels doped with MXene which provides high photothermal conversion efficiency and electrical conductivity as a medium. Simultaneously, the ionic gel-based eT-patch having excellent optical transparency actualizes real-time observation of skin response and melanoma treatment process under photothermal and electrical stimulation (PES) co-therapy. Systematical cellular study on anti-tumor mechanism of the eT-patch under PES treatment revealed that eT-patch under PES treatment can synergically trigger cancer cell apoptosis and pyroptosis, which together lead to the death of melanoma cells. Due to the obvious advantages of relatively safe and less side effects in healthy organs, the developed eT-patch provides a promising cost-effective therapeutic strategy for skin tumors and will open a new avenue for biomedical applications of ionic gels.

Chloroplast-Inspired Carrier Circulation for Improved Photoelectrochemical Photodetectors Based on Ti2CTx Nanosheets

Here, a photoelectrochemical (PEC) photodetector with good flexibility and high photoresponsivity was successfully fabricated in a vertical structure, where the MXene (Ti2CTx) nanosheet and carbon black electrode were separated by adenosine triphosphate/nicotinamide adenine dinucleotide phosphate (ATP/NADPH)-incorporated solid-state electrolyte. The photocurrent and photoresponsivity can reach 1.84 μA/cm2 and 8.89 μA/W, respectively, under a light intensity of 90 mW/cm2 at a bias potential of 0.6 V, which are approximately 2.3 times those of Ti2CTx nanosheets. The addition of ATP and NADPH to the electrolyte also leads to a large decrease of the rise time from 0.76 to 0.26 s. Furthermore, the photodetector can continue to function and maintain stability under 45° bending and after 500 cycles of bending, indicating a robust device structure and great flexibility. The performance enhancement of the PEC photodetector can be attributed to the synergistic effect of electrolyte additives on Ti2CTx nanosheets, where ATP and NADPH greatly enhance the circulation and utilization of photogenerated carriers. This work suggests that the incorporation of chloroplast-inspired carrier circulation with two-dimensional nanosheets could achieve efficient light-current conversion, providing a new strategy to improve the performance of PEC-type photodetectors.