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The extraction of interstitial fluid (ISF) from skin using microneedles (MNs) has attracted growing interest in recent years due to its potential for minimally invasive diagnostics and biosensors. ISF collection by absorption into a hydrogel MN patch is a promising way that requires the materials to have outstanding swelling ability. Here, a gelatin methacryloyl (GelMA) patch is developed with an 11 × 11 array of MNs for minimally invasive sampling of ISF. The properties of the patch can be tuned by altering the concentration of the GelMA prepolymer and the crosslinking time; patches are created with swelling ratios between 293% and 423% and compressive moduli between 3.34 MPa and 7.23 MPa. The optimized GelMA MN patch demonstrates efficient extraction of ISF. Furthermore, it efficiently and quantitatively detects glucose and vancomycin in ISF in an in vivo study. This minimally invasive approach of extracting ISF with a GelMA MN patch has the potential to complement blood sampling for the monitoring of target molecules from patients., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Atopic dermatitis (AD), a chronic and inflammatory skin disease, has brought huge physiological and psychological burdens to patients, which causes wide concerns in society. Herein, a multifunctional microneedle (MN) patch is proposed integrated with a desirable moisturizer and intelligent drug delivery capacity for AD treatment. Such MN patch consists of hyaluronic acid (HA) backing and near‐infrared (NIR) responsive tips containing black phosphorous quantum dots (BPQDs), low‐melting agarose, polyvinylpyrrolidone (PVP), and triamcinolone acetonide (TA). Among them, the soluble HA serves as a long‐term moisturizer for relieving dryness symptoms of AD. By introducing the NIR excitable and photothermal responsive BPQDs into agarose, the state of the composite material can be adjusted intelligently via NIR, thus achieving controllable release of the encapsulated TA in tips. Besides, PVP with enough mechanical strength can help MNs successfully penetrate the thickened skin of AD patients. Based on these advantages, it is demonstrated that the multifunctional MN patch reveals a satisfactory therapeutic effect in the AD model of Balb/c mice. These results indicate the potential values of the proposed MN patch in the treatment of AD skin diseases and other related biomedical fields. [ABSTRACT FROM AUTHOR]

Soft tissue injuries (STIs) are the most common cause of extremity pain and motion dysfunction. Persistent inflammatory activation of immune cells characterized by senescence‐associated secretory phenotype (SASP) and mitochondrial stress are considered the primary causes of STIs, a pathological process also termed inflammaging. Meanwhile, scavenging excessive "cellular waste" in the inflammaging microenvironment and further activating tissue repair processes remain elusive. Herein, an anti‐inflammaging photothermal hydrogel microneedle patch for treating STIs is developed. Taurine‐loaded Prussian blue nanoparticles (Taurine@PB) are encapsulated in a methacrylate‐based hyaluronic acid hydrogel (HAMA) and further fabricated into taurine@PB@HAMA@microneedles (TPH@MN) patches. The acidic microenvironment of chronic inflammation and mild photothermal effects promote taurine release and anti‐inflammaging immunomodulation, inhibiting mitochondrial stress via the SIRT3‐NF‐κB axis to promote glycolytic metabolic microenvironment of neutrophils reprogramming toward oxidative phosphorylation metabolism. Furthermore, TPH@MN activates macrophage efferocytosis and initiates the process of tissue repair. In mouse models of chronic diabetic wounds and tibialis anterior (TA) muscle injury, TPH@MN inhibits SASP expression and promotes STIs healing through thermosensitized anti‐inflammaging immunomodulation. In summary, TPH@MN circumvents the side effects of systemic administration, providing new translatable options in the treatment modalities for patients suffering from STIs worldwide. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is an emerging technique for treating tumors. Especially, topical administration of photosensitizers (PSs) is more favorable for superficial tumor treatments with low systematic phototoxicity. Yet, ineffective migration of PSs to targeted tumor tissues and rapid consumption of O2 during PDT greatly limit their effects. Herein, PS‐loaded microneedle (MN) patches with O2 propellant for a deeper and faster transdermal delivery of PS and improved PDT by embedding sodium percarbonate (SPC) into dissolving poly(vinyl pyrrolidone) MNs are presented. It is shown that SPC in the MNs can react with surrounding fluid to generate gaseous oxygen bubbles, forming vigorous fluid flows and thus greatly enhancing PS of chlorin e6 (Ce6) penetration in both hydrogel models and skin tissues. Reactive oxygen species (ROS) in hypoxic breast cancer cells (4T1 cells) are greatly increased by rapid penetration of PS and relief of hypoxia in vitro, and Ce6‐loaded SPC MNs show an excellent cell‐killing effect. Moreover, lower tumor growth rate and tumor mass after a 20‐d treatment in tumor‐bearing mice model verify the improved PDT in gaseous oxygen‐droved delivery of PS. This study demonstrates a facile yet effective route of MN delivery of PSs for improved PDT in hypoxic tumor treatment. [ABSTRACT FROM AUTHOR]