Diabetes affects millions of people worldwide and the number of diagnoses continues to climb annually. Though several effective medications and therapeutic methods have been developed to treat type 1 (T1DM) and type 2 (T2DM) diabetes mellitus, direct insulin injection remains the only effective treatment for insulin resistant (IR) diabetes patients. Here, we immobilize insulin in a crystalline mesoporous metal-organic framework (MOF), NU-1000, and obtain a high loading of ∼40 wt % in only 30 min. The acid-stable MOF capsules are found to effectively prevent insulin from degrading in the presence of stomach acid and the digestive enzyme, pepsin. Furthermore, the encapsulated insulin can be released from NU-1000 under simulated physiological conditions.

Metal-organic frameworks (MOFs) are porous, crystalline materials comprised of metal nodes and organic linkers. Here, a Zr-based MOF named NU-1000 is used to encapsulate and protect an enzyme. The encapsulation and subsequent protection of enzymes in solid supports is important for the potential industrialization of enzymes as chemical catalysts. NU-1000 is shown to be capable of stabilizing the enzyme under harsh conditions, and in addition, the encapsulated enzyme is shown to maintain full functionality.

The versatile optical and biological properties of a localized surface plasmon resonance (LSPR) sensor that responds to protein conformational changes are illustrated. The sensor detects conformational changes in a surface-bound construct of the calcium-sensitive protein calmodulin. Increases in calcium concentration induce a 0.96 nm red-shift in the spectral position of the LSPR extinction maximum (λ max ). Addition of a calcium chelating agent forces the protein to return to its original conformation and is detected as a reversal of the λ max shift. As opposed to previous work, this work demonstrates that these conformational changes produce a detectable shift in λ max even in the absence of a protein label, with a signal:noise ratio near 500. In addition, the protein conformational changes reversibly switch both the wavelength and intensity of the resonance peak, representing an example of a bimodal plasmonic component that simultaneously relays two distinct forms of optical information. This highly versatile plasmonic device acts as a biological sensor, enabling the detection of calcium ions with a biologically-relevant limit of detection of 23 μM, as well as the detection of calmodulin-specific protein ligands.

Natural inspiration: A bioinspired functional material in the form of a hydrogel created by cross‐linking an engineered version of calmodulin, a protein which undergoes a conformational change in response to ligand binding (see schematic representation), with a four‐armed poly(ethylene glycol) molecule terminated with acrylate groups decreased in volume by 20 % when treated with the ligand trifluoperazine. Multiple cycles of gel swelling and shrinkage were possible.