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Nanodiamonds exhibit exceptional colloidal properties in aqueous media that lead to a wide range of applications in nanomedicine and other fields. Nevertheless, the role of surface chemistry on the hydration of nanodiamonds remains poorly understood. Here, we probed the water hydrogen bond network in aqueous dispersions of nanodiamonds by infrared, Raman, and X-ray absorption spectroscopies applied in situ in aqueous environment. Aqueous dispersions of nanodiamonds with hydrogenated, carboxylated, hydroxylated, and polyfunctional surface terminations were compared. A different hydrogen bond network was found in hydrogenated nanodiamonds dispersions compared to dispersions of nanodiamonds with other surface terminations. Although no hydrogen bonds are formed between water and hydrogenated surface groups, a long-range disruption of the water hydrogen bond network is evidenced in hydrogenated nanodiamonds dispersion. We propose that this unusual hydration structure results from electron accumulation at the diamond–water interface.

The structure of aqueous alcohol solutions at the molecular level for many decades has remained an intriguing topic in numerous theoretical and practical investigations. The aberrant thermodynamic properties of water-alcohol mixtures are believed to be caused by the differences in energy of hydrogen bonding between water-water, alcohol-alcohol, and alcohol-water molecules. We present the Raman scattering spectra of water, ethanol, and water-ethanol solutions with 20 and 70 vol % of ethanol thoroughly measured and analyzed at temperatures varying from -10 to +70 °C. Application of the MCR-ALS method allowed for each spectrum to extract contributions of molecules with different strengths of hydrogen bonding. The energy (enthalpy) of formation/weakening of hydrogen bonds was calculated using the slope of Van't Hoff plot. The energy of hydrogen bonding in 20 vol % of ethanol was found the highest among all the samples. This finding further supports appearance of clathrate-like structures in water-ethanol solutions with concentrations around 20 vol % of ethanol.

Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven to be efficient drug carriers. The advantages of both ND and MSNs were hereby integrated in the new composite material, ND@MSN. The optical properties provided by the ND core rendered the nanocomposite suitable for microscopy imaging in fluorescence and reflectance mode, as well as super-resolution microscopy as a STED label; whereas the porous silica coating provided efficient intracellular delivery capacity, especially in surface-functionalized form. This study serves as a demonstration how this novel nanomaterial can be exploited for both bioimaging and drug delivery for future theranostic applications.

Although vodka is a reasonably pure mixture of alcohol and water, beverage drinks typically show differences in appeal among brands. The question immediately arises as to the molecular basis, if any, of vodka taste perception. This study shows that commercial vodkas differ measurably from ethanol-water solutions. Specifically, differences in hydrogen-bonding strength among vodkas are observed by (1)H NMR, FT-IR, and Raman spectroscopy. Component analysis of the FT-IR and Raman data reveals a water-rich hydrate of composition E x (5.3 +/- 0.1)H(2)O prevalent in both vodka and water-ethanol solutions. This composition is close to that of a clathrate-hydrate observed at low temperature, implying a cage-like morphology. A structurability parameter (SP) is defined by the concentration of the E x (5.3 +/- 0.1)H(2)O hydrate compared to pure ethanol-water at the same alcohol content. SP thus measures the deviation of vodka from "clean" ethanol-water solutions. SP quantifies the effect of a variety of trace compounds present in vodka. It is argued that the hydrate structure E x (5.3 +/- 0.1)H(2)O and its content are related to the perception of vodka.

The interaction of nanodiamond (ND) particles produced by detonation synthesis with water molecules in ND water suspensions was studied using Raman and photoluminescence spectroscopy. To address the role of the surface chemistry of ND particles, NDs with heterogeneous surface groups as well as ND particles enriched with carboxyl-, hydroxyl-, and fluorine-containing surface groups were investigated. The influence of the nanodiamond particles on the shape and position of the water valence band in the Raman spectra of ND water suspensions was demonstrated for the first time. Changes in the water band parameters take place up to 1.5 mg/mL of NDs in all studied suspensions and are most pronounced for the ND functionalized with COOH groups. A correlation between increasing ND luminescence intensity and strengthening of hydrogen bonds formed at the interface of ND and water molecules in water suspensions of variously functionalized NDs was found. The most intense ND luminescence was detected for the ND functionalized with OH groups, forming the strongest hydrogen bonds among the studied samples.

A multifunctional core-shell nanocomposite platform consisting of a photoluminescent nanodiamond (ND) core with uniform porous silica coatings is presented. This design intended for drug delivery applications allows simultaneous stable fluorescent imaging with high loading capacity of bioactive molecules. Despite irregularly shaped starting cores, well-dispersed and uniformly shaped nanocomposite particles can be produced. Moreover, after optimization of the silica source-to-diamond ratio, the thickness of the porous layer can be tuned by adjusting the ethanol amount, allowing rational nanoparticle size control. The ND key property, photoluminescence, is not quenched regardless of coating with thick silica layers. The high loading capacity for incorporation of active agents, provided by the introduced porous layer, is demonstrated by adsorption of a hydrophobic model drug to the composite particles. The loading degree, as compared to a pure ND, increased by two orders of magnitude from 1 wt% for the ND to >100 wt% for the composite particles. Combining these two material classes, which both have well-documented excellent performance especially in biomedical applications, for the NDs with emphasis, but not exclusively, on imaging and mesoporous silica (MSN) on drug delivery, the advantages of both are shown here to be synergistically integrated into one multifunctional nanocomposite platform.

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