Salmonella enterica biofilm-mediated dispersal by nitric oxide donors in association with cellulose nanocrystal hydrogels

Protected by extracellular polymers, microbes within biofilms are significantly more resistant to disinfectants. Current research has been instrumental in identifying nitric oxide donors and hydrogels as potential disinfectant additives. Nitric oxide (NO) donors are considered a very promising molecule as biofilm dispersal agents and hydrogels have recently attracted a lot of interest due to their biocompatible properties and ability to form stable thin films. When the NO donor MAHMA NONOate was dissolved in phosphate saline buffer, it was able to reduce the biomass of well-established biofilms up to 15% for at least 24 h of contact time. Encapsulation of MAHMA NONOate and molsidomine within a hydrogel composed of cellulose nanocrystals (CNC) has shown a synergistic effect in dispersing well-established biofilms: after 2 h of exposure, moderate but significant dispersion was measured. After 6 h of exposure, the number of cells transitioning from the biofilm to the planktonic state was up to 0.6 log higher when compared with non-treated biofilms. To further explore the transport processes of NO donors within hydrogels, we measured the nitric oxide flux from gels, at 25°C for a composite of 0.1 µM MAHMA NONOate–CNC. Nitric oxide diffuses up to 500 µm from the hydrogel surface, with flux decreasing according to Fick’s law. 60% of NO was released from the hydrogel composite during the first 23 min. These data suggest that the combined treatments with nitric oxide donor and hydrogels may allow for new sustainable cleaning strategies

In situ electrochemical generation of nitric oxide for neuronal modulation

Understanding the function of nitric oxide, a lipophilic messenger in physiological processes across nervous, cardiovascular and immune systems, is currently impeded by the dearth of tools to deliver this gaseous molecule in situ to specific cells. To address this need, we have developed iron sulfide nanoclusters that catalyse nitric oxide generation from benign sodium nitrite in the presence of modest electric fields. Locally generated nitric oxide activates the nitric oxide-sensitive cation channel, transient receptor potential vanilloid family member 1 (TRPV1), and the latency of TRPV1-mediated Ca2+ responses can be controlled by varying the applied voltage. Integrating these electrocatalytic nanoclusters with multimaterial fibres allows nitric oxide-mediated neuronal interrogation in vivo. The in situ generation of nitric oxide in the ventral tegmental area with the electrocatalytic fibres evoked neuronal excitation in the targeted brain region and its excitatory projections. This nitric oxide generation platform may advance mechanistic studies of the role of nitric oxide in the nervous system and other organs.National Institute of Neurological Disorders and Stroke (Grant 5R01NS086804)National Institutes of Health BRAIN Initiative (Grant 1R01MH111872

Influence of polymer composition on the sensitivity towards nitrite and nitric oxide of colorimetric disposable test strips

The influence of polymer composition on the sensitivity towards nitrite (NO 2 − ) and nitric oxide (NO) of a series of 19 polymeric hydrogel films has been stud- ied. The polymers, based on the hydrophilic monomer 2- hydroxyethylmethacrylate (HEMA), are able to encapsu- late the colorimetric indicator 1,2-diaminoanthraquinone (DAQ) and to respond to NO 2 − and NO by visual chang- es. In the case of nitrite, the calculated limits of detection (LOD) for two of the polymeric sensors (10 μ M) are very close to the sensitivity estimated for free DAQ in solution (LOD 5 μ M), but with the advantage of a solid supported sensor with the format of a disposable test- strip made with affordable starting chemicals. The re- sults are interpreted taking into account the nature and proportions of monomers and cross-linkers used for the synthesis of polymers. Key factors for obtaining sensi- tive materials are the hydro philic character of the film along with the utilization of low levels of cross-linker and the use of an acidic monomer, like acrylic acid, as a building block.Financial support from the Spanish MINECO (CTQ2015-68429-R) and Fundació Caixa Castelló-UJI (P1·1B2015-76) is acknowledged. V. F. thanks the financial support from UJI (predoctoral fellowship). We thank SCIC/UJI for technical assistance