Antimicrobial Peptides: Powerful Biorecognition Elements to Detect Bacteria in Biosensing Technologies

Abstract

Bacterial infections represent a serious threat in modern medicine. In particular, biofilm treatment in clinical settings is challenging, as biofilms are very resistant to conventional antibiotic therapy and may spread infecting other tissues. To address this problem, biosensing technologies are emerging as a powerful solution to detect and identify bacterial pathogens at the very early stages of the infection, thus allowing rapid and effective treatments before biofilms are formed. Biosensors typically consist of two main parts, a biorecognition moiety that interacts with the target (i.e., bacteria) and a platform that transduces such interaction into a measurable signal. This review will focus on the development of impedimetric biosensors using antimicrobial peptides (AMPs) as biorecognition elements. AMPs belong to the innate immune system of living organisms and are very effective in interacting with bacterial membranes. They offer unique advantages compared to other classical bioreceptor molecules such as enzymes or antibodies. Moreover, impedance-based sensors allow the development of label-free, rapid, sensitive, specific and cost-effective sensing platforms. In summary, AMPs and impedimetric transducers combine excellent properties to produce robust biosensors for the early detection of bacterial infections.

Label-Free Biosensors for Laboratory-Based Diagnostics of Infections: Current Achievements and New Trends

“…The need to develop electrochemical sensors has become especially urgent for biological agent indication systems in which early detection or monitoring (for example, environmental safety, biosafety, or monitoring molecular markers of the infection process) is of great importance [71,73,[96][97][98].…”

“…The prospect of electrochemical label-free biosensors is undeniable, since they do not require complex or expensive equipment, can be used in the field, and even be implanted into the human body for continuous monitoring of various biologically active compounds [48,71,73,96].…”

“…To expand the analytical capabilities of electrochemical biosensors, work is underway to improve the methods of immobilization of the biocomponent on the electrode, to miniaturize the sensor elements, and to increase their stability. The main limitation of the use of biosensors in medicine, biomedical research, and environmental protection is associated with the need to use one type of sensor to determine only one compound [50,71,73,96].…”

“…The applied layer increases stiffness, thus, raising the Q-factor of the oscillator, which has a positive effect on sensitivity of the biosensor. In sensors with the applied piezoelectric layer, the sensitivity to variations in the attached mass reaches 175 Hz/pg [96].…”

Pseudonajide is an antibiotic peptide derived from snake venom that alter cell wall and membrane integrity interfering on biofilm formation.

“…Microcolonies then form and mature, with establishment and maintenance of the structure occurring by both matrix and cell accumulation (9), followed by dispersion, the final step of biofilm formation (10). There are several advantages to this form (11): a biofilm community is difficult to treat due to the physical barrier against antibiotics and immune system factors (12); and the structure is related to much higher antimicrobial resistance (13). In most cases, the first treatment option for biofilm on medical devices is removal of the devices themselves, leading to increases in both patient suffering and health system financial expenditures (14).…”