Ionophore-Based Potassium Selective Fluorescent Organosilica Nano-Optodes Containing Covalently Attached Solvatochromic Dyes

Fluorescent nanoprobes containing ionophores and solvatochromic dyes (SDs) were previously reported as an alternative to chromoionophore-based nano-optodes. However, the small-molecular SDs are prone to leakage and sequestration in complex samples. Here, we chemically attached the SDs to the surface of organosilica nanospheres through copper-catalyzed Click chemistry to prevent dye leakage. The nano-optodes remained well responsive to K+ even after exposure to a large amount of cation-exchange resin, which acted as a sink of the SDs. The potassium nanoprobes exhibited a dynamic range between 1 μM to 10 mM and a good selectivity thanks to valinomycin. Preliminary sensing device based on a nylon filter paper and agarose hydrogel was demonstrated. The results indicate that the covalent anchoring of SDs on nanospheres is promising for developing ionophore-based nanoprobes.

Investigating homeopathic potencies with membrane bound solvatochromic dyes

Background Solvatochromic dyes have demonstrated themselves to be useful probes in the molecular-level study of homeopathic potencies. The range of dyes available, and their broad division into two main electronic structural groups, is permitting a detailed investigation of the fundamental nature of potencies. The immobilisation of solvatochromic dyes on transparent membranes takes these investigations to a new level of investigative precision. Aims To attach as many different solvatochromic dyes as possible to triacetylcellulose membranes, and where successful, to observe in detail the spectroscopic changes that occur on exposure to potencies. Immobilisation of dyes onto membranes de-couples the initial dye-potency interaction from later aggregation processes, thereby allowing a host of questions to be asked about what exactly potencies are doing to solvatochromic dyes and in turn indicating what the identities of potencies are likely to be. Methodology A number of methods have been explored for covalently linking dyes to membranes, which at the same time maintain the integrity of the solvatochromic chromophore. Immobilised dyes, in contrast to dyes in solution, behave differently, which means water-insoluble dyes for instance, can be used under a range of solution conditions that were not possible previously. Results and discussion Results from three positively solvatochromic dyes show that potencies cause a bathochromic shift in their spectra, confirming what has been seen previously with encapsulated dyes but with greater clarity. Results can be explained by invoking a polarising effect of potencies and differential stabilisation of the dyes’ ground and excited electronic states. The kinetics of the dye-potency interaction indicate the effect of potency reaches a maximum and then declines. Conclusion Immobilisation of solvatochromic dyes presents a significant step forward in the ability to investigate homeopathic potencies at the physico-chemical level.

Interaction between Solvatochromic Dyes and Water Sampled from a Natural Source Treated with High Dilutions of Phosphorus

Background Highly diluted and succussed solutions interact with solvatochromic dyes, indicating that changes in solvent and solute polarity could be related to their mechanism of action. It is not known, however, how the activity associated with succussed high dilutions is transferred to untreated water and what the limits of this process are. Aims The aims of the present study were to ascertain whether a succussed high dilution of phosphorus (1.5 × 1−59 M; Phos 30cH) seeded into a natural water source that fed a fjord and two connected lakes could propagate itself through the lake system (total volume 2200 m3) and, moreover, whether the process could be tracked using solvatochromic dyes. Methods Samples of water were collected before and after seeding, at different times and places throughout the lake system. Controls comprised water taken from an untreated and adjacent, but independent, lake (1385 m3). Results Water samples taken up to 72 hours after the source treatment produced significant increases (p ≤ 0.03) in the absorbance of the solvatochromic dye methylene violet (MV), while samples from the control lake produced no changes. Conclusions The study indicates that activity associated with Phos 30c can propagate itself through large volumes of water, causing changes throughout a whole connected lake system, and that these changes can be tracked using the solvatochromic dye MV. This in turn means the use of homeopathic medicines in large volumes of drinking water, in farming and ecological contexts, now has the potential to be assessed with physico-chemical monitoring.

Characterization of Antimonium crudum Activity Using Solvatochromic Dyes

Background The mechanism by which highly diluted and agitated solutions have their effect is still unknown, but the development in recent years of new methods identifying changes in water and solute dipole moments is providing insights into potential modes of action. Objective The objective of the current study was to compare the biological effects of Antimonium crudum (AC) previously obtained by our group and already described in the literature with now measurable physico-chemical effects on solvatochromic dyes. Methods Different dilutions of AC and succussed water have been characterized with respect to their effect on the visible spectra of the solvatochromic dyes methylene violet (MV), a pyridinium phenolate (ET33), and a dimethylamino naphthalenone (BDN) compared with in-vitro action against Leishmania amazonensis-infected macrophages. Results Dye responses varied according to the dye used and the level of AC dilution and results were found to corroborate previously published in-vivo and in-vitro effects of AC. In addition, a very significant enhancement in the absorbance increase of MV was seen using the supernatant from AC 200cH-treated cells (15%; p < 0.0001) over that seen with AC 200cH itself (4%; p = 0.034), suggesting the amplification of ultra-high dilution effects by biological systems. Furthermore, supernatants from AC-treated cells increased the range of dilutions of AC that were capable of producing effects on the spectra of MV. The effect of AC dilutions on dye ET33 was eliminated by a weak electric current passed through potency solutions. Conclusion The data confirm a correspondence between the biological effects of dilutions of AC in-vitro and physico-chemical effects on solvatochromic dyes as measured by changes in their visible spectra. Results also indicate high dilutions of AC are sensitive to exposure to electric currents and biological systems.