Hydrophobin‐Coated Solid Fluorinated Nanoparticles for ¹⁹F‐MRI

Abstract

In recent years, fluorine‐magnetic resonance imaging (19F‐MRI) has emerged as a promising diagnostic technique, complementary to traditional proton magnetic resonance imaging (1H‐MRI) and easily translatable for clinical use, providing in‐depth in vivo quantification without the use of radioactive agents. This creates a need for the development of appropriate delivery systems for highly omniphobic fluorinated probes. The use of the film‐forming protein hydrophobin (HFBII) represents a sustainable and simple method to invert the philicity of fluorinated surfaces. Here, the ability of HFBII to form a rigid protein monolayer on superfluorinated coatings rendering them hydrophilic is shown, a property that is also retained in biological environment. This approach is then translated to directly disperse a solid superfluorinated 19F‐MRI probe, PERFECTA, in aqueous solution through the formation of core‐shell hydrophobin stabilized PERFECTA nanoparticles (NPs). The obtained NPs are fully characterized in terms of morphology, magnetic properties, colloidal stability, protein corona formation, cellular viability, and imaging performance.

Multibranched-Based Fluorinated Materials: Tailor-Made Design of 19F-MRI Probes

“…Being solid at room temperature, established liquid PFC formulation procedures cannot be directly applied, thus requiring the development of different approaches. To date, we developed several types of colloidal formulations containing PERFECTA, which display optimal relaxation times, T 1 and T 2 and confirm its excellent suitability as 19 F-MR tracer (Figure a–h). ,, …”

“…PEG-based surfactants typically display a stealth effect to ensure stability in the physiological milieu and reduce formation of protein corona, which is necessary to minimize undesired blood clearance . However, it has been shown that PEG can lead to antibody formation, thus accelerating blood clearance, , promoting researchers to explore PEG alternatives. ,, Therefore, we explored a class of amphiphilic proteins, hydrophobins, as possible nonimmunogenic stabilizers for obtaining PERFECTA formulations with reduced sizes and stealth properties (Figure c,g) . Hydrophobin-II (HFBII) displays a highly hydrophobic patch enabling, for example, the formation of HFBII films on hydrophobic and fluorinated switching surface. − This rationale was applied to disperse PERFECTA in HFBII aqueous solutions resulting in the formation of 50 nm PERFECTA solid NPs coated by a protein shell.…”

“…According to these results, the PERFECTA half-life could be further improved by exploiting the ultrastructure of polymeric formulations. Importantly, these polymeric NPs show excellent colloidal stability, high loading yields, and effective MRI properties as a reduced T 1 compared to those obtained with earlier PERFECTA formulations, resulting in efficient imaging tracers. ,, …”

“…(h) 19 F cellular uptake quantified using both 19 F-NMR and 19 F-MRI (SNR) experiments for microglial cells labeled with HFBII-NPs for different incubation times. Reproduced with permission from ref . Copyright 2022 The Authors.…”

“…(g) @PERFECTA HFBII-FNPs (scale bar 100 nm). Reproduced with permission from ref . Copyright 2022 The Authors.…”