Innate Immune Mechanisms with a Focus on Small-Molecule Microbe-Host Cross Talk

Biofilm aggregates and the host airway-microbial interface

Biofilms are multicellular microbial aggregates that can be associated with host mucosal epithelia in the airway, gut, and genitourinary tract. The host environment plays a critical role in the establishment of these microbial communities in both health and disease. These host mucosal microenvironments however are distinct histologically, functionally, and regarding nutrient availability. This review discusses the specific mucosal epithelial microenvironments lining the airway, focusing on: i) biofilms in the human respiratory tract and the unique airway microenvironments that make it exquisitely suited to defend against infection, and ii) how airway pathophysiology and dysfunctional barrier/clearance mechanisms due to genetic mutations, damage, and inflammation contribute to biofilm infections. The host cellular responses to infection that contribute to resolution or exacerbation, and insights about evaluating and therapeutically targeting airway-associated biofilm infections are briefly discussed. Since so many studies have focused on Pseudomonas aeruginosa in the context of cystic fibrosis (CF) or on Haemophilus influenzae in the context of upper and lower respiratory diseases, these bacteria are used as examples. However, there are notable differences in diseased airway microenvironments and the unique pathophysiology specific to the bacterial pathogens themselves.

A Review of Recent Advances in Flexible Wearable Sensors for Wound Detection Based on Optical and Electrical Sensing

Chronic wounds that are difficult to heal can cause persistent physical pain and significant medical costs for millions of patients each year. However, traditional wound care methods based on passive bandages cannot accurately assess the wound and may cause secondary damage during frequent replacement. With advances in materials science and smart sensing technology, flexible wearable sensors for wound condition assessment have been developed that can accurately detect physiological markers in wounds and provide the necessary information for treatment decisions. The sensors can implement the sensing of biochemical markers and physical parameters that can reflect the infection and healing process of the wound, as well as transmit vital physiological information to the mobile device through optical or electrical signals. Most reviews focused on the applicability of flexible composites in the wound environment or drug delivery devices. This paper summarizes typical biochemical markers and physical parameters in wounds and their physiological significance, reviews recent advances in flexible wearable sensors for wound detection based on optical and electrical sensing principles in the last 5 years, and discusses the challenges faced and future development. This paper provides a comprehensive overview for researchers in the development of flexible wearable sensors for wound detection.

Electrochemical Detection of Multianalyte Biomarkers in Wound Healing Efficacy

The targeted diagnosis and effective treatments of chronic skin wounds remain a healthcare burden, requiring the development of sensors for real-time monitoring of wound healing activity. Herein, we describe an adaptable method for the fabrication of carbon ultramicroelectrode arrays (CUAs) on flexible substrates with the goal to utilize this sensor as a wearable device to monitor chronic wounds. As a proof-of-concept study, we demonstrate the electrochemical detection of three electroactive analytes as biomarkers for wound healing state in simulated wound media on flexible CUAs. Notably, to follow pathogenic responses, we characterize analytical figures of merit for identification and monitoring of bacterial warfare toxin pyocyanin (PYO) secreted by the opportunistic human pathogen Pseudomonas aeruginosa. We also demonstrate the detection of uric acid (UA) and nitric oxide (NO^•), which are signaling molecules indicative of wound healing and immune responses, respectively. The electrochemically determined limit of detection (LOD) and linear dynamic range (LDR) for PYO, UA, and NO^• fall within the clinically relevant concentrations. Additionally, we demonstrate the successful use of flexible CUAs for quantitative, electrochemical detection of PYO from P. aeruginosa strains and cellular NO^• from immune cells in the wound matrix. Moreover, we present an electrochemical examination of the interaction between PYO and NO^•, providing insight into pathogen-host responses. Finally, the effects of the antimicrobial agent, silver (Ag⁺), on P. aeruginosa PYO production rates are investigated on flexible CUAs. Our electrochemical results show that the addition of Ag⁺ to P. aeruginosa in wound simulant decreases PYO secretion rates.