Encapsulation of enzyme into mesoporous cages of metal–organic frameworks for the development of highly stable electrochemical biosensors

Abstract

The thermal stability of biosensors based on the confinement of an enzyme within MOFs was significantly improved.

Light or Heat? The Origin of Cargo Release from Nanoimpeller Particles Containing Upconversion Nanocrystals under IR Irradiation

“…The absolute quantum yield of the UV and blue emission of Tm 3+ doped upconversion nanocrystals under a moderate irradiation power density has not been reported, thus we calculate its upper limit based on the value of a two‐photon upconversion process, which was reported as 0.10 ± 0.05% for a 30 nm NaYF 4 :Yb 3+ , Er 3+ nanocrystal, or 0.30 ± 0.10% for a 30 nm NaYF 4 :Yb 3+ , Er 3+ @NaYF 4 nanocrystal under a 150 W cm −2 980 nm irradiation . Under the commonly used power density for biological applications (1–10 W cm −2 ), these values are reduced to 0.0035% and 0.010% at 4 W cm −2 , considering the quantum yield is a constant in the saturation region and reduces linearly with the power density in the region below the saturation threshold (about 115 W cm −2 ) (see the Supporting Information). For a UV or blue light activated photochemical reaction, a three‐photon upconversion process is required.…”

“…In photodynamic therapy, this reaction involves the excitation of photosensitizers (such as zinc phthalocyanine, hypericin, and chlorin e6) and subsequent energy transfer to generate singlet oxygen . Other photoreactions that have been studied include the photocleavage of o‐nitrobenzyl ester or ether (where the breaking of the C–O bonds results in the release of molecules such as fluorescein, siRNA, D‐luciferin, and folic acid) the photo‐induced collapse of polymer backbones,and ring‐opening and closing reactions of dithienylethene isomers triggered by the upconverted light . In these examples, the product generation is based on the reaction occurrence, regardless of its efficiency.…”

Shaping Luminescent Properties of Yb3+ and Ho3+ Co‐Doped Upconverting Core–Shell β‐NaYF4 Nanoparticles by Dopant Distribution and Spacing

“…This is typically attributed to the significantly increased surface‐to‐volume ratio of small UCNPs favoring quenching of the activator luminescence by surface defects as well as ligands and solvent molecules with high‐energy vibrations . This can be diminished by passivating core nanoparticles with a sufficiently thick and close shell . The need to improve UCNP performance inspired the synthesis of many sophisticated multishell structures involving inert and active, that is, lanthanide‐doped shells, to better control energy transfer processes, minimize surface defects, and shield sensitizer and activator lanthanide ions from the potentially quenching environment .…”

Micro‐ and Nanoscopic Imaging of Enzymatic Electrodes: A Review

“…The respective dimensions of enzyme and MOF cavity are 4 × 4.4 × 6.8 nm 3 and 5.5 nm in diameter. Confocal image of a crystal of MOF (around 2 μm) showed an even distribution of enzyme throughout the crystal, [63] which was furthermore confirmed by SEM-EDS images showing even distribution of sulfur in the crystal (Figure 3). This characterization was performed before immobilization of the enzyme-loaded MOF on a glassy carbon electrode, on which MET was established with hydroquinone as a redox mediator.…”