Peptide nucleic acid and antifouling peptide based biosensor for the non-fouling detection of COVID-19 nucleic acid in saliva.

The electrochemical biosensor with outstanding sensitivity and low cost is regarded as a viable alternative to current clinical diagnostic techniques for various disease biomarkers. However, their actual analytical use in complex biological samples is severely hampered due to the biofouling, as they are also highly sensitive to nonspecific adsorption on the sensing interfaces. Herein, we have constructed a non-fouling electrochemical biosensor based on antifouling peptides and the electroneutral peptide nucleic acid (PNA), which was used as the recognizing probe for the specific binding of the viral RNA of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Different from the negatively charged DNA probes that will normally weaken the biosensors' antifouling capabilities owing to the charge attraction of positively charged biomolecules, the neutral PNA probe will generate no side-effects on the biosensor. The biosensor demonstrated remarkable sensitivity in detecting SARS-CoV-2 viral RNA, possessing a broad linear range (1.0 fM - 1.0 nM) and a detection limit down to 0.38 fM. Furthermore, the sensing performance of the constructed electrochemical biosensor in human saliva was nearly similar to that in pure buffer, indicating satisfying antifouling capability. The combination of PNA probes with antifouling peptides offered a new strategy for the development of non-fouling sensing systems capable of assaying trace disease biomarkers in complicated biological media.

Antibacterial and Antiviral Coating on Surfaces through Dopamine-Assisted Codeposition of an Antifouling Polymer and In Situ Formed Nanosilver.

Bacteria and viruses can adhere onto diverse surfaces and be transmitted in multiple ways. A bifunctional coating that integrates both antibacterial and antiviral activities is a promising approach to mitigate bacterial and viral infections arising from a contaminated surface. However, current coating approaches encounter a slow reaction, limited activity against diverse bacteria or viruses, short-term activity, difficulty in scaling-up, and poor adaptation to diverse material surfaces. Here, we report a new one-step strategy for the development of a polydopamine-based nonfouling antibacterial and antiviral coating by the codeposition of various components. The in situ formed nanosilver in the presence of polydopamine was incorporated into the coating and served as both antibacterial and antiviral agents. In addition, the coassembly of polydopamine and a nonfouling hydrophilic polymer was constructed to prevent the adhesion of bacteria and viruses on the coating. The coating was prepared on model surfaces and thoroughly characterized using various surface analytical techniques. The coating exhibited strong antifouling properties with a reduction of nonspecific protein adsorption up to 90%. The coating was tested against both Gram-positive and Gram-negative bacteria and showed long-term antibacterial effectiveness, which correlated with the composition of the coating. The antiviral activity of the coating was evaluated against human coronavirus 229E. A possible mechanism of action of the coating was proposed. We anticipate that the optimized coating will have applications in the development of infection prevention devices and surfaces.

A novel antibacterial and antifouling nanocomposite coated endotracheal tube to prevent ventilator-associated pneumonia.

BACKGROUND: The endotracheal tube (ETT) is an essential medical device to secure the airway patency in patients undergoing mechanical ventilation or general anesthesia. However, long-term intubation eventually leads to complete occlusion, ETTs potentiate biofilm-related infections, such as ventilator-associated pneumonia. ETTs are mainly composed of medical polyvinyl chloride (PVC), which adheres to microorganisms to form biofilms. Thus, a simple and efficient method was developed to fabricate CS-AgNPs@PAAm-Gelatin nanocomposite coating to achieve dual antibacterial and antifouling effects. RESULTS: The PAAm-Gelatin (PAAm = polyacrylamide) molecular chain gel has an interpenetrating network with a good hydrophilicity and formed strong covalent bonds with PVC-ETTs, wherein silver nanoparticles were used as antibacterial agents. The CS-AgNPs@PAAm-Gelatin coating showed great resistance and antibacterial effects against Staphylococcus aureus and Pseudomonas aeruginosa. Its antifouling ability was tested using cell, protein, and platelet adhesion assays. Additionally, both properties were comprehensively evaluated using an artificial broncho-lung model in vitro and a porcine mechanical ventilation model in vivo. These remarkable results were further confirmed that the CS-AgNPs@PAAm-Gelatin coating exhibited an excellent antibacterial capacity, an excellent stain resistance, and a good biocompatibility. CONCLUSIONS: The CS-AgNPs@PAAm-Gelatin nanocomposite coating effectively prevents the occlusion and biofilm-related infection of PVC-ETTs by enhancing the antibacterial and antifouling properties, and so has great potential for future clinical applications.

Novel Barrier Enclosure for Both Aerosol and Droplet Protection Model.

Emergency physicians are on the front lines of treating patients with highly infectious respiratory diseases. Personal protective equipment is one defense against contamination from droplet and aerosol secretions. Intubation is a procedure that greatly can increase provider's risk of exposure. Utilization of an intubation box has been discussed and recommended on social media platforms. There has been scant literature demonstrating the effectiveness of such devices. This study aimed to determine degree of droplet contamination to the intubator utilizing a novel barrier enclosure with a fluorescent simulated respiratory contagion. This model confirmed both added protection to the providers preforming intubation, and reduction of spread of the droplets when such a device is applied to patient care.

On the effect of biofouling on the minimum propulsion power of ships for safe navigation in realistic conditions.

This study first examines the minimum power requirements of a tanker according to the IMO 2013 Interim Guideline (IMO 2013). For the estimation of the added resistance in waves a recently introduced semi-empirical method is used. Secondly, the influence of the increase in surface roughness of the hull and propeller due to fouling is investigated, reflecting the actual condition of a ship in service. The results show that even if ships are fulfilling the IMO 2013 Guideline, they may become unsafe in operation. Lastly, the uncertainties involved in the assessment procedure are discussed. The investigation conducted is particularly of interest for the assessment of the safety of ships now being idle or used as floating storage due to the impact of the pandemic COVID-19 on the world economy, while they are expected to go again into service once the demand for transport recovers.