Label-free super-resolution chemical imaging of biomedical specimens

Raman microscopy provides chemically selective imaging by exploiting intrinsic vibrational properties of specimens. Yet, a fast acquisition, low phototoxicity, and non-specific (to a vibrational/electronic mode) super-resolution method has been elusive for tissue imaging. We demonstrate a single-pixel-based approach, combined with robust structured illumination, that enables fast super-resolution in stimulated Raman scattering microscopy at low power levels. The methodology is straightforward to implement and compatible with thick biological specimens, therefore paving the way for probing complex biological systems when exogenous labelling is challenging.

Designing Chemically Selective Liquid Crystalline Materials that Respond to Oxidizing Gases

Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively...

New chlorin e6 amide derivatives with fragments of 1,3-diaminopropane

In this work, we studied the interaction of methylpheophorbide a with 1,3-diaminopropane and proposed a simple method for the synthesis of chlorin e6 derivatives with one, two, and three amino groups on the periphery of the macrocycle. It is shown that, when methylpheophorbide a acts on 1,3-diaminopropane in a medium of chloroform or methylene chloride, the exocycle opens chemically selectively and chlorin e6 13-amide derivative of with an amino group attached by a spacer of three methylene groups forms (chlorin e6 13-N-(3-aminopropyl)amide 15,17-dimethyl ether). By the action of 1,3-diaminopropane on chlorin e6 13-N-(3-aminopropyl)amide 15,17-dimethyl ether at room temperature without solvent, chlorin e6 13,17-N,N'-(3-aminopropyl) can be chemically selective diamide 15-methyl ether and chlorin e6 13,17-N,N',N''-(3-aminopropyl)triamide with two and three amino groups, respectively. The preparation of di- and triaminochlorins can be carried out both from chlorin e6 13-N-(3-aminopropyl)amide of 15,17-dimethyl ether, and directly from methylpheophorbide a without isolation of the intermediate monoaminochlorin. In the latter case, after the methylpheophorbide a exocycle is opened with 1,3-diaminopropane in chloroform or methylene chloride medium, the solvent is distilled off from the reaction mixture and the resulting monoaminochlorin reacts with the 1,3-diaminopropane present in the mixture without solvent. The structure of the obtained mono-, di, and triaminochlorins is confirmed by IR and NMR spectroscopy.

Electrochemistry of Single-Vesicle Events

Neuronal transmission relies on electrical signals and the transfer of chemical signals from one neuron to another. Chemical messages are transmitted from presynaptic neurons to neighboring neurons through the triggered fusion of neurotransmitter-filled vesicles with the cell plasma membrane. This process, known as exocytosis, involves the rapid release of neurotransmitter solutions that are detected with high affinity by the postsynaptic neuron. The type and number of neurotransmitters released and the frequency of vesicular events govern brain functions such as cognition, decision making, learning, and memory. Therefore, to understand neurotransmitters and neuronal function, analytical tools capable of quantitative and chemically selective detection of neurotransmitters with high spatiotemporal resolution are needed. Electrochemistry offers powerful techniques that are sufficiently rapid to allow for the detection of exocytosis activity and provides quantitative measurements of vesicle neurotransmitter content and neurotransmitter release from individual vesicle events. In this review, we provide an overview of the most commonly used electrochemical methods for monitoring single-vesicle events, including recent developments and what is needed for future research.