Protein-Based Films as Antifouling and Drug-Eluting Antimicrobial Coatings for Medical Implants

Polyaromatic Hydrocarbon-Functionalized 2D MXene-Based 3D Porous Antifouling Nanocomposite with Long Shelf Life for High-Performance Electrochemical Immunosensor Applications

Affinity-based electrochemical (AEC) biosensors have gained more attention in the field of point-of-care management. However, AEC sensing is hampered by biofouling of the electrode surface and degradation of the antifouling material. Therefore, a breakthrough in antifouling nanomaterials is crucial for the fabrication of reliable AEC biosensors. Herein, for the first time, we propose 1-pyrenebutyric acid-functionalized MXene to develop an antifouling nanocomposite to resist biofouling in the immunosensors. The nanocomposite consisted of a 3D porous network of bovine serum albumin cross-linked with glutaraldehyde with functionalized MXene as conductive nanofillers, where the inherited oxidation resistance property of functionalized MXene improved the electrochemical lifetime of the nanocomposite. On the other hand, the size-extruded porous structure of the nanocomposite inhibited the biofouling activity on the electrode surface for up to 90 days in real samples. As a proof of concept, the antifouling nanocomposite was utilized to fabricate a multiplexed immunosensor for the detection of C-reactive protein (CRP) and ferritin biomarkers. The fabricated sensor showed good selectivity over time and an excellent limit of detection for CRP and ferritin of 6.2 and 4.2 pg/mL, respectively. This research successfully demonstrated that functionalized MXene-based antifouling nanocomposites have great potential to develop high-performance and low-cost immunosensors.

Aptasensor-encapsulating semi-permeable proteinosomes for direct target detection in non-treated biofluids

Detecting biomarkers in biofluids directly without sample treatments makes molecular diagnostics faster and more efficient. Aptasensors, the nucleic acid-based molecular biosensors, can detect a wide range of target molecules, but their susceptibility to degradation and aggregation by nucleases and charged proteins, respectively, limits their direct use in clinical samples. In this work, we demonstrate that when aptasensors are encapsulated in proteinosomes, the protein-based liposome mimics, clinically important small molecules can be sensitively and selectively detected in non-treated specimens, such as 100 % unpurified serum. As serum albumin is used to form the membrane, the nanomeshed proteinosomes become semi-permeable and antifouling, which enables exclusive admission of small molecules while blocking unwanted large proteins. Consequently, the enclosed aptasensors can maintain close-to-optimal performance for target binding, and nucleolytic degradation and electrostatic aggregation are effectively suppressed. Three different structure-switching aptamers specific for estradiol, dopamine, and cocaine, respectively, are demonstrated to fully conserve their high affinities and specificities inside the microcapsules. The shielding effect of proteinosomes is indeed exceptional; the enclosed DNA aptasensors remain completely intact over 18 h in serum and even in an extremely concentrated DNase solution (1 mg/ml, ∼300,000× the serum level). Moreover, the proteinosome-mediated compartmentalization enables independent operation of multiple aptasensors in the same mixture. Hence, simultaneous real-time sensing of two different targets is demonstrated with different operation modes, 'recording' target appearance and 'reporting' target concentration changes. This work is the first demonstration of small-molecule-specific aptasensors operating with optimal performance in serum environments and will find promising applications in molecular diagnostics.

Protein-based bioactive coatings: from nanoarchitectonics to applications

Protein-based bioactive coatings have emerged as a versatile and promising strategy for enhancing the performance and biocompatibility of diverse biomedical materials and devices. Through surface modification, these coatings confer novel biofunctional attributes, rendering the material highly bioactive. Their widespread adoption across various domains in recent years underscores their importance. This review systematically elucidates the behavior of protein-based bioactive coatings in organisms and expounds on their underlying mechanisms. Furthermore, it highlights notable advancements in artificial synthesis methodologies and their functional applications in vitro. A focal point is the delineation of assembly strategies employed in crafting protein-based bioactive coatings, which provides a guide for their expansion and sustained implementation. Finally, the current trends, challenges, and future directions of protein-based bioactive coatings are discussed.

Transparent and Superhydrophilic Flexible Protein Films with Antifogging and Self-Cleaning Attributes

Cyanoglycoside-modified flexible protein films, exhibiting a high level of transparency of ≈46 to 83%, were successfully prepared from lysozyme and glycerol with varying amounts of amygdalin (20, 40, and 60%) using water as a solvent. The increasing percentage of amygdalin leads to a drastic improvement of the hydrophilicity of the surface with a decrease in the water contact angle to 5.6°, resulting in superhydrophilicity. The increasing percentage of amygdalin led to a significant improvement in the surface's hydrophilicity, resulting in a reduced water contact angle of 5.6° and achieving superhydrophilicity. This superhydrophilic characteristic is particularly relevant to the excellent antifogging and self-cleaning properties of the resulting protein films. In addition to enhanced flexibility, the films also exhibited considerably improved thermal stability with a 40% loading of amygdalin in the protein solution. The superior mechanical, optical, and thermal properties of amygdalin-modified films are due to the strong hydrogen bonding with the peptides of lysozyme, as evidenced by the disappearance of amide bands in the cured protein films. Therefore, these transparent protein films, with their antifogging and enhanced thermal stability properties, can be potentially used for different packaging and coating applications.

Controlled Release of Drug-Encapsulated Protein Films with Various Sodium Dodecyl Sulfate Concentrations

Protein-based drug carriers are ideal drug-delivery platforms because of their biocompatibility, biodegradability, and low toxicity. Many types and shapes of protein-based platforms, including nanoparticles, hydrogels, films, and minipellets, have been prepared to deliver drug molecules. In this study, protein films containing the desired amounts of doxorubicin (DOX) as cancer drugs were developed using a simple mixing method. The release ratio and rate of DOXs were dependent on the surfactant concentration. The drug release ratio was controlled within the range of 20-90% depending on the amount of the surfactant used. The protein film surface was analyzed using a microscope before and after drug release, and the relationship between the degree of film swelling and the drug release ratio was discussed. Moreover, the effects of cationic surfactants on the protein film were investigated. Non-toxic conditions of the protein films were confirmed in normal cells, while the toxicity of the drug-encapsulated protein film was confirmed in cancer cells. Remarkably, it was observed that the drug-encapsulated protein film could eliminate 10-70% of cancer cells, with the extent of efficacy varying based on the surfactant amount.

Phase Behavior of Aqueous Mixtures of Sodium Alginate with Fish Gelatin: Effects of pH and Ionic Strength

The phase behavior of aqueous mixtures of fish gelatin (FG) and sodium alginate (SA) and complex coacervation phenomena depending on pH, ionic strength, and cation type (Na⁺, Ca²⁺) were studied by turbidimetric acid titration, UV spectrophotometry, dynamic light scattering, transmission electron microscopy and scanning electron microscopy for different mass ratios of sodium alginate and gelatin (Z = 0.01-1.00). The boundary pH values determining the formation and dissociation of SA-FG complexes were measured, and we found that the formation of soluble SA-FG complexes occurs in the transition from neutral (pH_c) to acidic (pH_φ1) conditions. Insoluble complexes formed below pH_φ1 separate into distinct phases, and the phenomenon of complex coacervation is thus observed. Formation of the highest number of insoluble SA-FG complexes, based on the value of the absorption maximum, is observed at рH_opt and results from strong electrostatic interactions. Then, visible aggregation occurs, and dissociation of the complexes is observed when the next boundary, pH_φ2, is reached. As Z increases in the range of SA-FG mass ratios from 0.01 to 1.00, the boundary values of рН_c, рH_φ1, рH_opt, and рH_φ2 become more acidic, shifting from 7.0 to 4.6, from 6.8 to 4.3, from 6.6 to 2.8, and from 6.0 to 2.7, respectively. An increase in ionic strength leads to suppression of the electrostatic interaction between the FG and SA molecules, and no complex coacervation is observed at NaCl and CaCl₂ concentrations of 50 to 200 mM.

Recent Developments in Multifunctional Antimicrobial Surfaces and Applications toward Advanced Nitric Oxide-Based Biomaterials

Implant-associated infections arising from biofilm development are known to have detrimental effects with compromised quality of life for the patients, implying a progressing issue in healthcare. It has been a struggle for more than 50 years for the biomaterials field to achieve long-term success of medical implants by discouraging bacterial and protein adhesion without adversely affecting the surrounding tissue and cell functions. However, the rate of infections associated with medical devices is continuously escalating because of the intricate nature of bacterial biofilms, antibiotic resistance, and the lack of ability of monofunctional antibacterial materials to prevent the colonization of bacteria on the device surface. For this reason, many current strategies are focused on the development of novel antibacterial surfaces with dual antimicrobial functionality. These surfaces are based on the combination of two components into one system that can eradicate attached bacteria (antibiotics, peptides, nitric oxide, ammonium salts, light, etc.) and also resist or release adhesion of bacteria (hydrophilic polymers, zwitterionic, antiadhesive, topography, bioinspired surfaces, etc.). This review aims to outline the progress made in the field of biomedical engineering and biomaterials for the development of multifunctional antibacterial biomedical devices. Additionally, principles for material design and fabrication are highlighted using characteristic examples, with a special focus on combinational nitric oxide-releasing biomedical interfaces. A brief perspective on future research directions for engineering of dual-function antibacterial surfaces is also presented.

Plasmonic photoreactors-coated plastic tubing as combined-active-and-passive antimicrobial flow sterilizer

Plastic materials are ubiquitous in medical devices and consumer goods. As bacterial contamination of plastic surfaces can pose significant health risks, there is a need for effective approaches both to inactivate bacteria on plastic surfaces and to prevent colonization of plastic surfaces. In this study, we evaluate a plasmonic photoreactor coating for plastic surfaces that provides both active and passive antimicrobial effects and implement a visible light-driven antibacterial flow sterilizer. We demonstrate that this approach inactivates bacteria in an aqueous suspension passed through a photoreactor-coated polyethylene tubing, achieving log reduction values (LRVs) > 5 for both Gram-positive and -negative bacteria under resonant LED illumination. Importantly, the antimicrobial flow sterilizers do not cause a detectable loss of functionality for monoclonal antibodies that were included in this work as an example of high-value biologics that require sterilization. Under ambient light illumination, the plasmonic photoreactor coating exhibits a significant inhibitory effect on bacterial colonization and biofilm formation. The inhibitory effect was substantially weaker for mammalian cells, indicating some selectivity in the protection provided by the coating.