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Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury. After various types of tissue injury, the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction. There is increasing evidence that oxidative stress, which is characterized by excessive production of hydrogen peroxide (H2O2), is an important cause of fibrosis. Therefore, we synthesized a biosensitive and efficient electrochemical H2O2sensor based on PtNi nanoparticle-doped N-reduced graphene oxide (PtNi-N-rGO) to detect H2O2released from transforming growth factor β1 (TGFβ1)-induced myofibroblast. In addition, the sensor could easily detect changes in H2O2in the lung and bronchoalveolar lavage fluid (BALF) of mice with pulmonary fibrosis. Furthermore, the sensor could also detect H2O2in activated hepatic stellate cells and the liver of carbon tetrachloride (CCl4)-induced liver fibrosis. Moreover, the alterations in H2O2detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) protein expression and the staining results of pathological sections. Taken together, these results highlight the use of H2O2sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.

Microneedles are considered to be an effective, convenient, non-invasive, biosafety and compliant medical technology for vaccinations, biomarker testing, medical aesthetics and other related fields. Nonetheless, further clinical and commercial translation of regular microneedles is hampered by challenges in manufacturability, cost variability, insufficient comfort, contamination and so on. Recent innovations in functional biomaterials and chemical engineering technologies have been applied to develop extensible and swellable hydrogel-forming microneedles, achieving precise and controlled drug delivery and localized sampling from the target tissues. In this review, we systematically summarize the latest development of the extensible and swellable hydrogel-forming microneedles, including deep point-of-care testing, drug deployment, wound healing and mucoadhesion improvement. In addition, further analysis of the challenges and prospects for clinical application of current strategies is well presented. It is believed that the combined efforts of engineering, material, pharmaceutical and clinical research will contribute to the future success of this clinical and commercial translation.