Lasers are the pillars of modern optics and sensing. Microlasers based on whispering-gallery modes (WGMs) are miniature in size and have excellent lasing characteristics suitable for biosensing. WGM lasers have been used for label-free detection of single virus particles, detection of molecular electrostatic changes at biointerfaces, and barcode-type live-cell tagging and tracking. The most recent advances in biosensing with WGM microlasers are described in this review. We cover the basic concepts of WGM resonators, the integration of gain media into various active WGM sensors and devices, and the cutting-edge advances in photonic devices for micro- and nanoprobing of biological samples that can be integrated with WGM lasers.

Metal-organic frameworks (MOFs) have settled in the scientific community over the last decades as versatile materials with several applications. Among those, zeolitic imidazolate framework 8 (ZIF-8) is a well-known MOF that has been applied in various and diverse fields, from drug-delivery platforms to microelectronics. However, the complex role played by the reaction parameters in controlling the size and morphology of ZIF-8 particles is still not fully understood. Even further, many individual reports propose different nucleation and growth mechanisms for ZIF-8, thus creating a fragmented view for the behavior of the system. To provide a unified view, we have generated a comprehensive data set of synthetic conditions and their final outputs and applied machine learning techniques to analyze the data. Our approach has enabled us to identify the nucleation and growth mechanisms operating for ZIF-8 in a given sub-space of synthetic variables space (chemical space) and to reveal their impact on important features such as final particle size and morphology. By doing so, we draw connections and establish a hierarchy for the role of each synthetic variable and provide with rule of thumb for attaining control on the final particle size. Our results provide a unified roadmap for the nucleation and growth mechanisms of ZIF-8 in agreement with mainstream reported trends, which can guide the rational design of ZIF-8 particles which ultimately determine their suitability for any given targeted application. Altogether, our work represents a step forward in seeking control of the properties of MOFs through a deeper understanding of the rationale behind the synthesis procedures employed for their synthesis.

Nanoarchitectonics can lead to electrode materials with enhanced electrocatalytic properties.

Composite materials featuring a synergic combination of interesting properties such as stimuli responsiveness and tailored porosity are highly appealing due to their multiple possible applications. We hereby present an example which brings together such features by using poly(N-isopropyl-acrylamide)-derived thermo-responsive microgels and Zn-based Metal Organic Framework (MOF) ZIF-8, capable of selective adsorption. Such a composite was obtained by including methacrylic acid as a co-monomer in the microgel, in order to position carboxylic acid moieties within the polymeric matrix, which via preconcentration of MOF precursors would trigger confined heterogeneous nucleation. The highly integrated composite obtained features thermoresponsivity and permanent porosity. Methylene blue adsorption/desorption experiments were performed, revealing a dramatic enhancement of its cargo capacity together with an increased release efficiency.