Effective drug delivery system based on hydrophobin and halloysite clay nanotubes for sustained release of doxorubicin

Bio-Based Surfactants and Biosurfactants: An Overview and Main Characteristics

Natural surfactants are surface-active molecules synthesized from renewable resources (i.e., plants, animals, or microorganisms) and possess properties comparable to conventional surfactants, making them an environmentally friendly potential alternative to petrochemical surfactants. Additionally, they exhibit biological properties such as anti-microbial properties, biodegradability, and less toxicity, allowing their use in everyday products with minimal risk to human health and the environment. Based on their mode of production, natural surfactants can be classified into first-generation or bio-based surfactants and second-generation or biosurfactants, although their definition may vary depending on the author in the literature. This review offers an extensive classification of bio-based surfactants and biosurfactants, focusing on their composition, natural sources, production methods, and potential applications across various industries. Furthermore, the main challenges and future perspectives are discussed.

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.

Cefixime loaded bare and functionalized halloysite nanocarriers and their biomedical applications

Effective drug delivery for is the foremost requirement for the complete recovery of the disease. Nanomedicine and nanoengineering has provided so many spaces and ideas for the drug delivery design, whether controlled, targeted, or sustained. Different types of nanocarriers or nanoparticles are aggressively designed for the drug delivery applications. Clay minerals are identified as a one of the potential nanocarrier for the drug delivery. Owing to their biocompatibility and very low cytotoxicity, clay minerals showing effective therapeutic applications. In the present investigation, clay mineral, i.e., Halloysite nano tubes are utilized as a nanocarrier for the delivery of antibiotic cefixime (CFX), a third-generation cephalosporin. The HNT was first functionalized with the sulfuric acid and then further treated with the 3-(aminopropyl)triethoxysilane (APTES). The drug is loaded on three different classifications of HNTs, i.e., Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT and their comparative analysis is established. Different characterization techniques such as X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), Transmission electron microscopy TEM), Brunauer-Emmett-Teller (BET), adsorption studies, and Thermogravimetric analysis (TGA) were performed to evaluate their chemical, structural, morphological, and thermal properties. TGA confirmed the encapsulation efficiency of Bare-CFX-HNT, Acid-CFX-HNT, and APTES-CFX-HNT as 42.65, 52.19, and 53.43%, respectively. Disk diffusion and MTT assay confirmed that the drug loaded HNTs have potential antibacterial activities and less cytotoxicity. The adsorption capacity of CFX with different HNTs are evaluated and Different adsorption and kinetic models have been discussed. Drug release studies shows that APTES-CFX-HNT showing sustained release of cefixime as compared to Bare-CFX-HNT and Acid-CFX-HNT.

Engineering design of asymmetric halloysite/chitosan/collagen sponge with hydrophobic coating for high-performance hemostasis dressing

Uncontrolled massive hemorrhage is a crucial cause of death, and developing efficient hemostatic materials are of great medical importance. Herein, we prepared a halloysite-chitosan-collagen composite sponge by directional freeze-drying method and coating the sponge by hydrophobic polydimethylsiloxane coating for rapid and effective hemostasis. The aligned channel structure of the sponge with a pore size of ~30 μm was beneficial for the transport of blood. Morphology and spectrum results suggested that chitosan and collagen are capable of adsorbing on the outer surface of HNTs due to the hydrogen bonding and electrostatic attractions. The directional freeze-dried sponge absorbed the majority of the blood within 10 s, and that process essentially completed in 30 s, which are faster than its non-directional counterpart. The composite sponges exhibited high antibacterial properties towards E. coli and S. aureus, and they are non-cytotoxic towards mouse fibroblasts and have high hemocompatibility. The hemostatic dressing avoided unnecessary blood loss because of excessive blood absorption. In vivo experiments of rats also confirmed the ability of the asymmetric sponges to rapidly clot and reduce reducing blood loss. This work developed a high-performance and hemostatic dressing by material design and processing technique, which shows a promising application in wound healing.

In Vitro Binding and Release Mechanisms of Doxorubicin from Nanoclays

Nanoclays have been developed as drug delivery systems, but their mechanisms of DOX delivery are unclear. Herein, unmodified nanoclays (halloysite, kaolinite, montmorillonite) were comprehensively studied on their in vitro binding and release mechanisms of DOX from both experimental and theoretical aspects. These nanoclays with high loading capacity (>50%) and encapsulation efficiency capacity (>90%) of DOX are attributed to the exposed hydroxyl groups and the Lewis base sites on the surfaces. Density functional theory calculations also confirmed that DOX is preferentially adsorbed on the Al-OH surfaces while adsorption on Si-O surfaces is limited. Besides this, the pH-responsive profiles of DOX release from nanoclays are related to the protonation of negatively charged nanoclays in weakly acidic solutions that makes it easier to dissociate with positively charged DOX. The in-depth mechanistic method in this work is widely applicable and demonstrates that nanoclays can be used as efficient nanocarriers for more biomedical applications.

Innovative surface bio-functionalization by fungal hydrophobins and their engineered variants

Research on innovative surface functionalization strategies to develop materials with high added value is particularly challenging since this process is a crucial step in a wide range of fields (i.e., biomedical, biosensing, and food packaging). Up to now, the main applied derivatization methods require hazardous and poorly biocompatible reagents, harsh conditions of temperature and pressure, and are time consuming and cost effective. The discovery of biomolecules able to adhere by non-covalent bonds on several surfaces paves the way for their employment as a replacement of chemical processes. A simple, fast, and environment-friendly method of achieving modification of chemically inert surfaces is offered by hydrophobins, small amphiphilic proteins produced by filamentous fungi. Due to their structural characteristics, they form stable protein layers at interfaces, serving as anchoring points that can strongly bind molecules of interest. In addition, genetic engineering techniques allow the production of hydrophobins fused to a wide spectrum of relevant proteins, providing further benefits in term of time and ease of the process. In fact, it is possible to bio-functionalize materials by simply dip-casting, or by direct deposition, rendering them exploitable, for example, in the development of biomedical and biosensing platforms.