Naphthalene and its Derivatives: Efficient Fluorescence Probes for Detecting and Imaging Purposes

Naphthylated LEGO-lipophosphonoxin antibiotics used as a fluorescent tool for the observation of target membrane perturbations preceding its disruption

Linker-Evolved-Group-Optimized-Lipophosphonoxins (LEGO-LPPO) are small synthetic modular peptidomimetics with promising antimicrobial activity. The LEGO-LPPO mechanism of antibacterial action has been determined to be the depolarization and disruption of bacterial membranes. Their modular nature is advantageous for fine tuning their biological properties. In order to optimize the structure of LEGO-LPPO even further, it is important to understand the interaction of LEGO-LPPO with bacterial membranes at the molecular level. In this work, we present the synthesis of five LEGO-LPPO (designated as1_naph2-4-G to5_naph2-4-G) molecules bearing fluorescent naphtylethyl moieties and their usage in the study of LEGO-LPPO behaviour in the membrane. Our goal was to characterize fluorescently labelled LEGO-LPPO under conditions that do not completely disrupt the membrane, mostly in the form of membrane-bound monomers. We observed the intramolecular interactions of hydrophobic modules of1_naph2-4-G in the buffer by detecting dynamic naphthyl excimers and their disappearance after1_naph2-4-G bind into the membranes. In the membrane, the molecule1_naph2-4-G slightly affects the membrane fluidity of DOPG membranes above the phase transition. The naphthyl fluorophore itself has fast and almost unrestricted rotation around ethylene linking groups (rinf= 0.010), which indicates a considerable chaotropic effect of the hydrophobic modules of1_naph2-4-G at the given depth of the membrane.1_naph2-4-G proved to be a useful model for observing the interaction of LEGO-LPPO antibiotics with the phospholipid bilayer enabling us to decipher its effects on membrane state and dynamics; its binding and penetration into the membrane, its structure and the particular depth that it occupies.

Environmentally sensitive fluorescence of the topical retinoid adapalene

Intrinsic fluorescence of drugs brings valuable information on their localization in the organism and their interaction with key biomolecules. In this work, we investigate the absorption and emission properties of the topical retinoid adapalene in different solvents and biological media. While the UVA/UVB absorption band does not exhibit any significant solvent-dependent behavior, a strong positive solvatochromism is observed for the emission. These results are in line with molecular modeling and simulations that show the presence of two quasi-degenerate states, i.e., a local π-π* and an intermolecular charge-transfer (ICT) state. However, molecular modeling also revealed that, whatever the solvent, at the corresponding equilibrium geometry the lowest and emissive excited state is the local π-π*. Finally, the potential of adapalene to act as a biological probe is demonstrated using albumin, DNA and micelles.

Unnatural Amino Acids for Biological Spectroscopy and Microscopy

Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.

A Synthetic Route to Highly Substituted 1-Aminonaphthalenes from Readily Available Benzaldehydes

We report an efficient route for the synthesis of highly substituted 1-aminonaphthalenes from benzaldehydes. The method employs a stereoselective Still-Gennari modification of the Horner-Wadsworth-Emmons olefination to afford (E)-benzylidenesuccinonitrile precursors, which undergo Bronsted acid mediated benzannulation to afford 1-aminonaphthalene derivatives in 35-95% yield. The abundance of commercially available benzaldehydes, coupled with the simplicity of our method, enables many previously unexplored naphthalene substitution patterns to become readily accessible.

Nanotechnology for brain tumor imaging and therapy based on π-conjugated materials: state-of-the-art advances and prospects

In contemporary biomedical research, the development of nanotechnology has brought forth numerous possibilities for brain tumor imaging and therapy. Among these, π-conjugated materials have garnered significant attention as a special class of nanomaterials in brain tumor-related studies. With their excellent optical and electronic properties, π-conjugated materials can be tailored in structure and nature to facilitate applications in multimodal imaging, nano-drug delivery, photothermal therapy, and other related fields. This review focuses on presenting the cutting-edge advances and application prospects of π-conjugated materials in brain tumor imaging and therapeutic nanotechnology.