Rational Design of Amphiphilic Peptides and Its Effect on Antifouling Performance

Electrochemical sensing interfaces based on hierarchically architectured zwitterionic peptides for ultralow fouling detection of alpha fetoprotein in serum

Herein, an electrochemical sensing platform based on zwitterionic peptide with a hierarchical structure was constructed for ultralow fouling and highly sensitive protein quantification. Through the combination of CPPPPEKEKEKEK and CPPPPEKEKEK peptides, hierarchical antifouling peptide brushes were formed and exhibited excellent antifouling property, which can be further modified with alpha fetoprotein (AFP) aptamer to achieve highly sensitive detection of AFP. The hierarchical peptide brush-based sensor system achieved an AFP quantification range from 1.0 fg mL^-1 to 1.0 ng mL^-1, with a very low limit of detection as low as 0.59 fg mL^-1. In addition, due to the superior antifouling property of the newly designed hierarchical peptide brushes, the electrochemical biosensor supported the quantification of AFP in solutions with a high concentration of nonspecific proteins without sacrifice in sensitivity. It is worth noting that the constructed antifouling biosensor ensured quantitative recruitment of AFP in clinical serum samples with acceptable accuracy when compared with the commonly used method in the hospital. The strategy of constructing sensing interfaces based on designed hierarchical peptide brushes provided an effective way to develop biosensors with both excellent antifouling capability and high sensitivity.

Surface Modification by Nano-Structures Reduces Viable Bacterial Biofilm in Aerobic and Anaerobic Environments

Bacterial biofilm formation on wet surfaces represents a significant problem in medicine and environmental sciences. One of the strategies to prevent or eliminate surface adhesion of organisms is surface modification and coating. However, the current coating technologies possess several drawbacks, including limited durability, low biocompatibility and high cost. Here, we present a simple antibacterial modification of titanium, mica and glass surfaces using self-assembling nano-structures. We have designed two different nano-structure coatings composed of fluorinated phenylalanine via the drop-cast coating technique. We investigated and characterized the modified surfaces by scanning electron microscopy, X-ray diffraction and wettability analyses. Exploiting the antimicrobial property of the nano-structures, we successfully hindered the viability of Streptococcus mutans and Enterococcus faecalis on the coated surfaces in both aerobic and anaerobic conditions. Notably, we found lower bacteria adherence to the coated surfaces and a reduction of 86–99% in the total metabolic activity of the bacteria. Our results emphasize the interplay between self-assembly and antimicrobial activity of small self-assembling molecules, thus highlighting a new approach of biofilm control for implementation in biomedicine and other fields.

Amphiphilic Peptide with Dual Functionality Resists Biofouling

Biofouling, the accumulation of organisms on surfaces, can lead to several undesirable phenomena, including hospital-acquired infections, blockage of water purification systems, and food contamination. The solution to the problem should be nontoxic and environmentally friendly, so that it could be applied on different surfaces and could come into contact with food, water, or human tissues. Peptides can provide such a solution, since they are biocompatible and biodegradable materials that can resist biofouling, either by preventing the attachment of organisms to the surface (antifouling) or by killing the bacteria (antimicrobial activity). This paper presents an amphiphilic peptide with antifouling, antimicrobial, and adhesive properties. The peptide adheres to titanium surfaces and inhibits the adhesion of both Gram-negative and Gram-positive bacteria to surfaces. In addition, it reduces the growth of bacteria in solution. This peptide has both antifouling and antimicrobial properties, which could be useful in health care systems, food packaging, and other systems that suffer from biocontamination.

The design and development of short peptide-based novel smart materials to prevent fouling by the formation of non-toxic and biocompatible coatings

Biofouling refers to the undesirable process that leads to the accumulation of microorganisms such as bacteria or fungi on substrates. This is one of the major concerns associated with several components of our regular life such as food, health, water and energy. In the healthcare sector, biofouling on medical devices is known to cause infections, which are often resistant to conventional antibiotics and lead to increase in the number of hospital and surgery-related deaths. One of the better ways to tackle the problem of biofouling is the development of smart antifouling materials that can produce a biocompatible, non-toxic, eco-friendly and functional coating and maintain a biological environment without any adverse effect. To this end, in the present study, we have reported the design and synthesis of two simple chemically modified peptides, namely, PA1 (PFB-VVD) and PA2 (PFB-LLE). The design as well as the amino acid sequence of the peptides contains three basic components that enable their ability to (i) self-assemble into functional coatings, (ii) bind with the desired surface via the bi-dentate coordination of dicarboxylate groups and (iii) exhibit antifouling activity and generate a non-toxic biocompatible supramolecular coating on the desired surface. PA1 having aspartic acid as the anchoring moiety exhibits better antifouling activity compared to PA2 that has glutamic acid as the anchoring moiety. This is probably due to the greater adhesive force or binding affinity of aspartic acid to the examined surface compared to that of glutamic acid, as confirmed by force measurement studies using AFM. Most importantly, the simple drop-coating method promises great advantages due to its ease of operation, which leads to a reduction in the production cost and increase in the scope of commercialization. To the best of our knowledge, this is the first attempt to develop an ultra-short peptide-based smart antifouling material with a dicarboxylate group as the surface binding moiety. Furthermore, these findings promise to provide further insights into antifouling mechanisms in the future by the development of a smart material using a dicarboxylate group as an anchoring moiety.

Durable, Stable, and Functional Nanopores Decorated by Self-Assembled Dipeptides

Nanopores have become an important tool for the detection and analysis of molecules at the single-molecule level. Surface modification of solid-state nanopores can improve their durability and efficiency. Peptides are ideal for surface modifications as they allow tailoring of multiple properties by a rational design of their sequence. Here, silicon nitride nanopores were coated by a dipeptide layer where a l-3,4-dihydroxyphenylalanine (DOPA) residue is the anchoring element and the other amino acid moiety is the functional element. DOPA binds tightly to many types of surfaces and allows a one-step functionalization of surfaces by simple immersion. As a result, the lifetime of coated nanopores increased from hours to months and the current-stability has significantly improved with respect to uncoated pores. This improvement is achieved by controlling the surface wettability and charge. Peptide-coated nanopores can be utilized as sensitive sensors that can be adjusted based on the choice of the functional moiety of the coated peptide. In addition, the coating slows down dsDNA translocation because of the DNA interaction with the pore coating.

Current Trends in Protein Engineering: Updates and Progress

Proteins are one of the most important and resourceful biomolecules that find applications in health, industry, medicine, research, and biotechnology. Given its tremendous relevance, protein engineering has emerged as significant biotechnological intervention in this area. Strategic utilization of protein engineering methods and approaches has enabled better enzymatic properties, better stability, increased catalytic activity and most importantly, interesting and wide range applicability of proteins. In fact, the commercialization of engineered proteins have manifested in economically beneficial and viable solutions for industry and healthcare sector. Protein engineering has also evolved to become a powerful tool contributing significantly to the developments in both synthetic biology and metabolic engineering. The present review revisits the current trends in protein engineering approaches such as rational design, directed evolution, de novo design, computational approaches etc. and encompasses the recent progresses made in this field over the last few years. The review also throws light on advanced or futuristic protein engineering aspects, which are being explored for design and development of novel proteins with improved properties or advanced applications.