Binding Interaction of Organofluorine–Serum Albumin: A Comparative Ligand-Detected 19F NMR Analysis

Self-Assembly of Precisely Fluorinated Albumin for Dual Imaging-Guided Synergistic Chemo-Photothermal-Photodynamic Cancer Therapy

Although albumin has been extensively used in nanomedicine, it is still challenging to fluorinate albumin into fluorine-19 magnetic resonance imaging (¹⁹F MRI)-traceable theranostics because existing strategies lead to severe ¹⁹F signal splitting, line broadening, and low ¹⁹F MRI sensitivity. To this end, 34-cysteine-selectively fluorinated bovine serum albumins (BSAs) with a sharp singlet ¹⁹F peak have been developed as ¹⁹F MRI-sensitive and self-assembled frameworks for cancer theranostics. It was found that fluorinated albumin with a non-binding fluorocarbon and a long linker is crucial for avoiding ¹⁹F signal splitting and line broadening. With the fluorinated BSAs, paclitaxel (PTX) and IR-780 were self-assembled into stable, monodisperse, and multifunctional nanoparticles in a framework-promoted self-emulsion way. The high tumor accumulation, efficient cancer cell uptake, and laser-triggered PTX sharp release of the BSA nanoparticles enabled ¹⁹F MRI-near infrared fluorescence imaging (NIR FLI)-guided synergistic chemotherapy (Chemo), photothermal and photodynamic therapy of xenograft MCF-7 cancer with a high therapeutical index in mice. This study developed a rational synthesis of ¹⁹F MRI-sensitive albumin and a framework-promoted self-emulsion of multifunctional BSA nanoparticles, which would promote the development of protein-based high-performance biomaterials for imaging, diagnosis, therapy, and beyond.

Solution-state NMR evaluation of molecular interaction between monoaromatic carboxylic acids and dissolved humic acid

Understanding the nature of interactions between the aromatic organic pollutants with dissolved humic acid (HA) is fundamental for the prediction of their environmental fate and subsequent development of efficient remediation methods. The present study employs solution-state ¹H/¹⁹F NMR methods to investigate the non-covalent interaction between aqueous peat humic acid (Aldrich HA) and monoaromatic carboxylic acids (CA), viz., 2, 6 diflourobenzoic acid (DFBA) and its non-fluorinated analog, benzoic acid (BA). NMR self-diffusion measurement of HA protons confirmed micellar nature indicating possibility of encapsulation of small molecules through host-guest interaction. ¹⁹F-¹H and ¹H-¹H saturation transfer difference (STD) experiments reveal the mode of insertion of CA into HA superstructure. The strength of interaction has been evaluated by analyzing T₁/T₂ relaxation times and self-diffusion coefficients of CA as a function of HA concentration. Association constants extracted for CA-HA complexes from NMR diffusion experiments reflected that the association between DFBA-HA (2.34 mM^-1) is significantly higher than that of BA-HA (0.97 mM^-1). The experimental outcome reiterated that substitution of -H with halogen atoms (-F in specific) to aromatic ring plays a dominant role in modulating the strength of association and mode of insertion of organic pollutants into HA superstructure. The present study emphasizes that AHA can be a potential remediating agent for organic contaminants due to its superior binding affinity compared to less humified extracted HA (EHA) from Karwar, Rajasthan, India.