Electrical monitoring of infection biomarkers in chronic wounds using nanochannels

Point-of-care detection devices for wound care and monitoring

Healthcare resources are heavily burdened by infections that impede the wound-healing process. A wide range of advanced technologies have been developed for detecting and quantifying infection biomarkers. Finding a timely, accurate, non-invasive diagnostic alternative that does not require a high level of training is a critical step toward arresting common clinical patterns of wound health decline. There is growing interest in the development of innovative diagnostics utilizing a variety of emerging technologies, and new biomarkers have been investigated as potential indicators of wound infection. In this review, we summarize diagnostics available for wound infection, including those used in clinics and still under development.

Electrochemical monitoring of enzymatic cleavage in nanochannels with nanoparticle-based enhancement: determination of MMP-9 biomarker

For the first time the use of nanoparticles as carriers of an enzymatic substrate immobilized inside nanoporous alumina membranes is proposed with the aim of amplifying the nanochannel blocking produced and, consequently, improving the efficiency of an enzyme determination through enzymatic cleavage. Streptavidin-modified polystyrene nanoparticles (PSNPs) are proposed as carrier agents, contributing to the steric and the electrostatic blockage due to the charge they present at different pH values. Electrostatic blockage is the predominant effect that governs the blockage in the interior of the nanochannel and is dependent not just in the charge inside the channel, but also in the polarity of the redox indicator used. Hence, the effect of using negatively charged ([Fe(CN)₆]^4-) and positively charged ([Ru(NH₃)₆]³⁺) redox indicator ions is studied for the first time. Under the optimum conditions, matrix-metalloproteinase 9 (MMP-9) is detected at clinically relevant levels (100-1200 ng/mL) showing a detection limit of 75 ng/mL and a quantification limit of 251 ng/mL with good reproducibility (RSD: 8%) and selectivity, also showing an excellent performance in real samples with acceptable recovery percentages (in the range around 80-110%). Overall, our approach represents a cheap and fast sensing methodology of great potential in point-of-care diagnostics.

Microbial Interplay in Skin and Chronic Wounds

Purpose of Review

Microbial infections in chronic wounds can often lead to lower-limb amputation, decrease in quality of life, and increase in mortality rate, and there is an unmet need to distinguish between pathogens and colonisers in these chronic wounds. Hence, identifying the composition of healthy skin microbiota, microbes associated with chronic wound and healing processes, and microbial interactions and host response in healing wounds vs. non-healing wounds can help us in formulating innovative individual-centric treatment protocols.

Recent Findings

This review highlights various metabolites and biomarkers produced by microbes that have been identified to modulate these interactions, particularly those involved in host–microbe and microbe–microbe communication. Further, considering that many skin commensals demonstrate contextual pathogenicity, we provide insights into promising initiatives in the wound microbiome research.

Summary

The skin microbiome is highly diverse and variable, and considering its importance remains to be a hotspot of medical investigations and research to enable us to prevent and treat skin disorders and chronic wound infections. This is especially relevant now considering that non-healing and chronic wounds are highly prevalent, generally affecting lower extremities as seen in diabetic foot ulcers, venous leg ulcers, and pressure ulcers. Pathogenic bacteria are purported to have a key role in deferring healing of wounds. However, the role of skin microflora in wound progression has been a subject of debate. In this review, we discuss biomarkers associated with chronic wound microenvironment along with the relevance of skin microflora and their metabolites in determining the chronicity of wounds.