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Precise, real-time monitoring of temperature in flexible and bioconformable formats finds applications in healthcare and disease diagnostics. There is interest in the fabrication of biocompatible and biodegradable devices that can be safely resorbed inside the body or easily disposed of in the environment, reducing waste. Here, a fully organic, silk-protein-based temperature sensor is reported with attractive properties such as flexibility, transparency, conformability, durability, and biodegradability together with high sensitivity and accuracy. The sensor is composed of a flexible, photoactive silk fibroin substrate, on which interdigitated electrodes are photolithographically micropatterned using a photoactive silk sericin–PEDOT:PSS conductive ink. A temperature sensitive layer comprising photoactive silk sericin and rGO is integrated on the electrodes. Finally, the sensor is sheathed in a fibroin layer to eliminate interference from humidity. The sensor exhibits a high sensitivity of −0.99% °C−1 in the temperature range of 20–50 °C along with excellent stability in humidity from 10 to 90% RH. It possesses high cycling stability over multiple heating/cooling cycles. These layers are covalently integrated, improving mechanical stability and the retention of electrochemical behavior under deformation. The sensor is shown for the monitoring of surface temperature, including rapid measurement of skin temperature with accuracy. Finally, the temperature sensor is able to effectively degrade over a period of ∼10 days under proteolytic conditions. Such sensors have potential in personalized healthcare monitoring devices, improving efficient disease detection and diagnosis.

Herein, we report the synthesis of silver nanoparticles (AgNPs) by a green route using the aqueous leaf extract of Morus indica L. V1. The synthesized AgNPs exhibited maximum UV-Vis absorbance at 460 nm due to surface plasmon resonance. The average diameter (~54 nm) of AgNPs was measured from HR-TEM analysis. EDX spectra also supported the formation of AgNPs, and negative zeta potential value (−14 mV) suggested its stability. Moreover, a shift in the carbonyl stretching (from 1639 cm−1 to 1630 cm−1) was noted in the FT-IR spectra of leaf extract after AgNPs synthesis which confirm the role of natural products present in leaves for the conversion of silver ions to AgNPs. The four bright circular rings (111), (200), (220) and (311) observed in the selected area electron diffraction pattern are the characteristic reflections of face centered cubic crystalline silver. LC-MS/MS study revealed the presence of phytochemicals in the leaf extract which is responsible for the reduction of silver ions. MTT assay was performed to investigate the cytotoxicity of AgNPs against two human cell lines, namely HepG2 and WRL-68. The antibacterial study revealed that MIC value of the synthesized AgNPs was 80 µg/ml against Escherichia coli K12 and Staphylococcus aureus (MTCC 96). Finally, the synthesized AgNPs at 10 µg/ml dosages showed beneficial effects on the survivability, body weights of the Bombyx mori L. larvae, pupae, cocoons and shells weights via enhancing the feed efficacy.

Thin polymeric films are being explored for biomedical uses such as drug delivery, biofiltration, biosensors, and tissue regeneration. Of specific interest is the formation of mechanically flexible sheets, which can be formed with controllable thickness for sealing wounds, or as biomimetic cellular constructs. Flexible substrates with precise micro‐ and nanopatterns can function as supports for cell growth with conformal contact at the biointerface. To date, approaches to form free‐standing, thin sheets are limited in the ability to present patterned architectures and micro/nanotextured surfaces. Other materials have a lack of degradability, precluding their application as cellular scaffolds. An approach is suggested using biocompatible and biodegradable films fabricated from silk fibroin. This work presents the fabrication and characterization of flexible, micropatterned, and biodegradable 2D fibroin sheets for cell adhesion and proliferation. A facile and scalable technique using photolithography is shown to fabricate optically transparent, strong, and flexible fibroin substrates with tunable and precise micropatterns over large areas. By controlling the surface architectures, the control of cell adhesion and spreading can be observed. Additionally, the base material is fully degradable via proteolysis. Through mechanical control and directing the adherent cells, it is possible to explore interactions of cells and the microscale geometric topography.

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The development of sustainable and degradable biosensors and bioelectronics has implications for implantable systems, as well in addressing issues of electronic waste. Mechanically flexible and bioresorbable sensors can find applications at soft biological interfaces. While devices typically use metallic and synthetic components and interconnects that are non-degradable or have the potential to cause adverse tissue reactions, the use of nature-derived materials and conducting polymers can provide distinct advantages. In particular, silk fibroin and sericin can provide a unique palette of properties, providing both structural and functional elements. Here, a fully organic, mechanically flexible biosensor in an integrated 3-electrode configuration is demonstrated. Silk sericin conducting ink is micropatterned on a silk fibroin substrate using a facile photolithographic process. Next, using a conducting polymer wire sheathed in silk fibroin, organic interconnects are used to form the electrical connections. This fully organic electrochemical system has competitive performance metrics for sensing in comparison to conventional systems, as verified by detection of a model analyte-ascorbic acid. The stability of the silk biosensor through biodegradation was observed, showing that the sensors can function for several days prior to failure. Such protein-based systems can provide a useful tool for biomonitoring of analytes in the body or environment for controlled periods of time, followed by complete degradation, as transient systems for various applications.

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