Two-dimensional (2D) MXenes have shown a great potential for chemical sensing due to their electric properties. In this work, a Ti₃C₂T_x/polypyrrole (MXene/PPy) nanocomposite has been synthesized and immobilized into a glassy carbon electrode to enable the simultaneous recognition of dopamine (DA) and uric acid (UA) under the interference of ascorbic acid (AA). The multilayer Ti₃C₂T_x MXene was prepared via the aqueous acid etching method and delaminated to a single layer nanosheet, benefiting the in-situ growth of PPy nanowires. The controllable preparation strategy and the compounding of PPy material remain great challenges for further practical application. A facile chemical oxidation method was proposed to regulate magnitude and density during the forming process of PPy nanowire, which promotes the conductivity and the electrochemical active site of this as-prepared nanomaterial. The MXene/PPy nanocomposite-modified electrode exhibited the selective determination of DA and UA in the presence of a high concentration of AA, as well as a wide linear range (DA: 12.5–125 μM, UA: 50–500 μM) and a low detection limit (DA: 0.37 μM, UA: 0.15 μM). More importantly, the simultaneous sensing for the co-existence of DA and UA was successfully achieved via the as-prepared sensor.

Exosomes derived from cancer cells have been recognized as a promising biomarker for minimally invasive liquid biopsy. Herein, a novel sandwich-type biosensor was fabricated for highly sensitive detection of exosomes. Amino-functionalized Fe₃O₄ nanoparticles were synthesized as a sensing interface with a large surface area and rapid enrichment capacity, while two-dimensional MXene nanosheets were used as signal amplifiers with excellent electrical properties. Specifically, CD63 aptamer attached Fe₃O₄ nanoprobes capture the target exosomes. MXene nanosheets modified with epithelial cell adhesion molecule (EpCAM) aptamer were tethered on the electrode surface to enhance the quantification of exosomes captured with the detection of remaining protein sites. With such a design, the proposed biosensor showed a wide linear range from 10² particles μL⁻¹ to 10⁷ particles μL⁻¹ for sensing 4T1 exosomes, with a low detection limit of 43 particles μL⁻¹. In addition, this sensing platform can determine four different tumor cell types (4T1, Hela, HepG2, and A549) using surface proteins corresponding to aptamers 1 and 2 (CD63 and EpCAM) and showcases good specificity in serum samples. These preliminary results demonstrate the feasibility of establishing a sensitive, accurate, and inexpensive electrochemical sensor for detecting exosome concentrations and species. Moreover, they provide a significant reference for exosome applications in clinical settings, such as liquid biopsy and early cancer diagnosis.

Exosomes have attracted increasing attention in the early diagnosis of tumors due to their participation in physiological and pathological processes. Herein, a novel label-free aptasensor based on the CuNi bimetallic metal–organic frameworks (MOFs) that was decorated with MXene quantum dots (MQDs) was fabricated for exosome sensing. The CuNi-MOFs functionalized with dual specific aptamers, CD63 and MUC1, served as an ideal nanocarrier and catalyst for efficient recognition and capture of target exosomes. Meanwhile, the MQDs with excellent electron transfer can promote the electrochemical catalytic performance of this designed aptasensor. It is noteworthy that the large specific surface area of 2D bimetallic CuNi-MOF nanosheets can offer plenty of exposed active sites and facilitate the connection of aptamers, thereby achieving the goal of specific capture and detection of exosomes. The as-prepared electrochemical aptasensor possesses a wide linear range of 1 × 10¹ to 1 × 10⁶ particles μL⁻¹ for exosome detection and a low detection limit of 5 particles μL⁻¹ (S/N = 3). Besides, the as-prepared aptasensor exhibited satisfactory electrochemical stability for the detection of exosomes, which can provide new ideas for clinical detection and tumor diagnosis.

With the aggravation of bacterial infections, sensitive detection and effective elimination materials are extensively essential to overcoming bacterial threats. Herein, a sensing and treating bio-platform was constructed by using MXene and silver nanowires (AgNWs) wrapped carbon fiber films (CMA). AgNWs with high aspect ratios were synthesized and then modified with MXene films via self-assembly to serve as the bio-platform. Due to the synergistic effect of conductive networks and surface chemistry, this bio-platform enabled the electrochemical detection of S. aureus in the range of 2 × 10²–2 × 10⁷ CFU per mL with a low detection limit of 0.35 CFU per mL, followed by high sensitivity, reproducibility, and reliability in real samples. Furthermore, this synergistic bio-platform exhibited a highly effective elimination rate of 99.45% against S. aureus and 99.8% against E. coli, respectively. This strategy demonstrates a facile approach to simultaneously enhancing bacterial identification and antibacterial performance.