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Desorption electrospray ionization mass spectrometry imaging (DESI‐MSI) is one of the least specimen destructive ambient ionization mass spectrometry tissue imaging methods. It enables rapid simultaneous mapping, measurement, and identification of hundreds of molecules from an unmodified tissue sample. Over the years, since its first introduction as an imaging technique in 2005, DESI‐MSI has been extensively developed as a tool for separating tissue regions of various histopathologic classes for diagnostic applications. Recently, DESI‐MSI has also emerged as a versatile technique that enables drug discovery and can guide the efficient development of drug delivery systems. For example, it has been increasingly employed for uncovering unique patterns of in vivo drug distribution, the discovery of potentially treatable biochemical pathways, revealing novel druggable targets, predicting therapeutic sensitivity of diseased tissues, and identifying early tissue response to pharmacological treatment. These and other recent advances in implementing DESI‐MSI as the tool for the development of novel therapies are highlighted in this review. [ABSTRACT FROM AUTHOR]

[Display omitted] Nose-to-brain delivery presents an attractive administration route for neuroactive drugs that suffer from compromised bioavailability or fail to pass the blood–brain barrier. However, the conventional gauge of effectiveness for intranasal delivery platforms primarily involves detecting the presence of the administered drug within the brain, with little insight into its precise localization within brain structures. This may undermine the therapeutic efficacy of drugs and hinder the design of systems that target specific brain regions. In this study, we designed two intranasal delivery systems for the antipsychotic drug, olanzapine, and evaluated its distribution in the rat brain following intranasal administration. The first evaluated system was an olanzapine-loaded microemulsion and the second one was nanoparticulate aqueous dispersion of olanzapine. Both systems exhibited characteristics that render them compatible for intranasal administration, and successfully delivered olanzapine to the brain. We further employed an ambient mass spectrometry imaging method, called desorption electrospray ionization mass spectrometry imaging, to visualize the signal intensity of olanzapine in different brain regions following the intranasal administration of these two systems. Substantial variations in the distribution patterns of olanzapine across various brain structures were revealed, potentially highlighting the importance of mass spectrometry imaging in designing and evaluating intranasal drug delivery platforms. [ABSTRACT FROM AUTHOR]

Cu 2+ -ion-modified graphene oxide nanoparticles, Cu 2+ -GO NPs, act as a heterogeneous catalyst mimicking functions of horseradish peroxidase, HRP, and of NADH peroxidase. The Cu 2+ -GO NPs catalyze the oxidation of dopamine to aminochrome by H 2 O 2 and catalyze the generation of chemiluminescence in the presence of luminol and H 2 O 2 . The Cu 2+ -GO NPs provide an active material for the chemiluminescence detection of H 2 O 2 and allow the probing of the activity of H 2 O 2 -generating oxidases and the detection of their substrates. This is exemplified with detecting glucose by the aerobic oxidation of glucose by glucose oxidase and the Cu 2+ -GO NP-stimulated chemiluminescence intensity generated by the H 2 O 2 product. Similarly, the Cu 2+ -GO NPs catalyze the H 2 O 2 oxidation of NADH to the biologically active NAD + cofactor. This catalytic system allows its conjugation to biocatalytic transformations involving NAD + -dependent enzyme, as exemplified for the alcohol dehydrogenase-catalyzed oxidation of benzyl alcohol to benzoic acid through the Cu 2+ -GO NPs-catalyzed regeneration of NAD + .