Hydrophobin HGFI improving the nanoparticle formation, stability and solubility of Curcumin

Preparation and Characterization of Hydrophobin 4-Coated Liposomes for Doxorubicin Delivery to Cancer Cells

Background: The properties of nanoparticle surfaces are crucial in influencing their interaction with biological environments, as well as their stability, biocompatibility, targeting abilities, and cellular uptake. Hydrophobin 4 (HFB4) is a class II HFB protein produced by filamentous fungi that has a natural ability to self-assemble at hydrophobic-hydrophilic interfaces. The biocompatible, non-toxic, biodegradable, and amphipathic properties of HFB4 render it valuable for improving the solubility and bioavailability of hydrophobic drugs. We have investigated the physicochemical properties, cellular uptake, and anticancer effects of empty and Doxorubicin (Dox)-loaded HFB4 liposomes (HFB4L) and compared them to those of PEGylated liposomes (PPL). Methods: The Pichia pastoris KM71H strain was used for HFB4 purification. Liposomes were prepared through the thin film hydration method and characterized. The cytotoxic effects of free Dox, Dox-HFB4, and Dox-PPL were assessed in MCF7 cells using the SRB Assay. Results: All formulations showed good size homogeneity and a spherical shape. The HFB4 coating enhanced the physicochemical stability of Dox-HFB4L over 60 days at 4 °C without significantly affecting Dox release from HFB4L. It increased Dox release at pH 5.4 compared to pH 7.4, indicating higher delivery of drugs into acidic tumor environments, similar to Dox-PPL. While both formulations showed increased cellular uptake compared to free Dox, they exhibited a lower anticancer effect due to the sustained release of Dox. Notably, Dox-HFB4L displayed greater cytotoxicity than Dox-PPL in MCF7 cells. Conclusions: HFB4L may offer superior benefits in terms of delivering drugs to an acidic tumor environment in a stable, non-toxic, and sustained manner.

Surface-Induced Hydrophobin Assemblies with Versatile Properties and Distinct Underlying Structures

Hydrophobins are remarkable proteins due to their ability to self-assemble into amphipathic coatings that reverse surface wettability. Here, the versatility of the Class I hydrophobins EASΔ15 and DewY in diverse nanosuspension and coating applications is demonstrated. The hydrophobins are shown to coat or emulsify a range of substrates including oil, hydrophobic drugs, and nanodiamonds and alter their solution and surface behavior. Surprisingly, while the coatings confer new properties, only a subset is found to be resistant to hot detergent treatment, a feature previously thought to be characteristic of the functional amyloid form of Class I hydrophobins. These results demonstrate that substrate surface properties can influence the molecular structures and physiochemical properties of hydrophobin and possibly other functional amyloids. Functional amyloid assembly with different substrates and conditions may be analogous to the propagation of different polymorphs of disease-associated amyloid fibrils with distinct structures, stability, and clinical phenotypes. Given that amyloid formation is not required for Class I hydrophobins to serve diverse applications, our findings open up new opportunities for their use in applications requiring a range of chemical and physical properties. In hydrophobin nanotechnological applications where high stability of assemblies is required, simultaneous structural and functional characterization should be carried out. Finally, while results in this study pertain to synthetic substrates, they raise the possibility that at least some members of the pseudo-Class I and Class III hydrophobins, reported to form assemblies with noncanonical properties, may be Class I hydrophobins adopting alternative structures in response to environmental cues.