All-in-One Photoactivated Inhibition of Butyrylcholinesterase Combined with Luminescence as an Activation and Localization Indicator: Carbon Quantum Dots@Phosphonate Hybrids.

Photopharmacology is a booming research area requiring a new generation of agents possessing simultaneous functions of photoswitching and pharmacophore. It is important that any practical implementation of photopharmacology ideally requires spatial control of the medicinal treatment zone. Thus, advances in the study of substances meeting all the listed requirements will lead to breakthrough research in the coming years. In this study, CQDs@phosphonate nanohybrids are presented for the first time and combine biocompatible and nontoxic luminescent carbon quantum dots (CQDs) with photoactive phosphonate enabling inhibition of butyrylcholinesterase (BChE), which is a prognostic marker of numerous diseases. The conjunction of these components in hybrids maintains photoswitching and provides enhancement of BChE inhibition. After laser irradiation with a wavelength of 266 nm, CQDs@phosphonate hybrids demonstrate a drastic increase of butyrylcholinesterase inhibition from 38% up to almost 100% and a simultaneous luminescence decrease. All the listed hybrid properties are demonstrated not only for in vitro experiments but also for complex biological samples, i.e., chicken breast. Thus, the most important achievement is the demonstration of hybrids characterized by a remarkable combination of all-in-one properties important for photopharmacology: (i) bioactivity toward butyrylcholinesterase inhibition, (ii) strong change of inhibition degree as a result of laser irradiation, luminescence as an indicator of (iii) bioactivity state, and of (iv) spatial localization on the surface of a sample.

Calibration of upconversion luminescence of lanthanide-doped nanoparticle suspensions using Raman scattering.

A new, to the best of our knowledge, internal reference method has been developed for the study of the upconversion luminescence of nanoparticle suspensions. This method provides correct analysis and comparison of the luminescent signals obtained under different conditions. To excite the echo signals of samples, it is proposed to use the radiation from an optical parametric oscillator at two wavelengths for the simultaneous excitation of the upconversion luminescence of particles and the Raman scattering signal of the medium in the Stokes region of the spectrum. Due to the linear dependence of the intensity of the Raman scattering of the medium on the excitation power density, the normalization of the upconversion luminescence signal of particles to the intensity of the Raman scattering of the medium makes it possible to eliminate the influences of the instability of the intensity of the laser radiation, light scattering by the medium, inaccuracies in alignment, etc. on the luminescence signal.

Machine learning algorithms to control concentrations of carbon nanocomplexes in a biological medium via optical absorption spectroscopy: how to choose and what to expect?

A solution of spectroscopic inverse problems, implying determination of target parameters of the research object via analysis of spectra of various origins, is an overly complex task, especially in case of strong variability of the research object. One of the most efficient approaches to solve such tasks is use of machine learning (ML) methods, which consider some unobvious information relevant to the problem that is present in the data. Here, we compare ML approaches to the problem of nanocomplex concentrations determination in human urine via optical absorption spectra, perform preliminary analysis of the data array, find optimal parameters for several of the most popular ML methods, and analyze the results.

High-performance size exclusion chromatography with online fluorescence and multi-wavelength absorbance detection for isolation of high-purity carbon dots fractions, free of non-fluorescent material.

The carbon dots (CDs) from natural nanographite oxide mixture (NGO-MIX) and from its fraction NGO (3.5-10K) recovered after ultrafiltration and dialysis were analyzed by 3D-excitation/emission matrix and high-performance size exclusion chromatography (HPSEC) combined with online fluorescence and absorbance detections. HPSEC chromatograms obtained simultaneously with absorption within the wavelength range 200-500 nm and fluorescence detection at λexc/λem = 270/450 nm/nm showed that NGO-MIX sample is not homogeneous and consist of well resolved CDs fractions with different sizes, absorption spectra and distinct fluorescence and non-fluorescence properties. Despite the twice higher fluorescence intensity of fraction NGO (3.5-10K) compared to the NGO-MIX, some impurity of non-fluorescent components was detected by HPSEC. The absorbance spectra of chromatographic peaks, extracted from the data of multi-wavelength absorbance detector, demonstrated different combinations of absorbance maxima. It means that different chromatographic peaks correspond to sized and chemically different CDs fractions. This study demonstrated for the first time the possibility of separating oxidized nanographite into homogeneous free from non-fluorescent material CDs fractions with their simultaneous spectroscopic characterization.

In vitro temperature sensing with up-conversion NaYF4:Yb3+/Tm3+-based nanocomposites: Peculiarities and pitfalls.

The luminescence intensity ratio method, exploiting the temperature-dependent luminescence of the thermally coupled energy levels, is regarded as a very promising approach for optical temperature measurement at the cellular level. In this study, it was found that bare NaYF4:Yb3+/Tm3+ nanoparticles cannot be used as a cellular thermosensor in principle because of their tendency to aggregate, which significantly affects the luminescent properties of the complex, introducing uncertainty in the intensity ratio measurement. NaYF4:Yb3+/Tm3+ up-conversion nanoparticles, coated with polyethylene glycol (PEG) and carboxyl groups (COOH), on the other hand, proved to be promising candidates for the role of thermosensors. For the first time the temperature sensitivity of the NaYF4:Yb3+/Tm3+@PEG@COOH thermosensor was calculated in water and in biotissues. It was found that the sensitivity of the thermosensor increased by 1.3 times during the transition from water to egg white and urine - from 1.17% × K-1 to 1.58% × K-1. This effect is associated with the chemical composition of the studied media. The results obtained suggest that using upconversion nanocomplexes as primary thermosensors is still difficult.

Boron-Doped Nanodiamonds as Anticancer Agents: En Route to Hyperthermia/Thermoablation Therapy.

Local targeted "inside-out" hyperthermia of tumors via nanoparticles is able to sensitize tumor cells to chemotherapy, radiation therapy, gene therapy, immunotherapy, or other effects, significantly reducing the duration and intensity of treatment. In this article, new nanomaterials are proposed to be used as anticancer agents: boron-doped nanodiamonds with sizes of about 10 nm synthesized for the first time by the high-temperature high-pressure (HTHP) method. The heating ability of boron-doped nanodiamonds was investigated under different heating conditions in different environments: water, chicken egg white, and MCF-7 breast cancer cells. It was discovered that, with the same conversion of the absorbed energy into heat, the ability to heat the environment when excited at a wavelength of 808 nm of boron-doped nanodiamonds is much higher than that of detonation nanodiamonds. It was established that boron-doped nanodiamonds are extremely promising for carrying out hyperthermia and thermoablation of tumors.

Absolute luminescence quantum yield for nanosized carbon particles in water as a function of excitation wavelength.

The absolute luminescence quantum yield Q as a function of excitation wavelength λex in a wide spectral range 270-470 nm was measured for the first time for the group of carbon nanoparticles dispersed in water: carbon dots (CD), detonation nanodiamonds (DND), as well as detonation nanodiamonds decorated with carbon dots (CD-DND). The luminescence quantum yield for DND increased after functionalization; the CD-decorated DND demonstrated significantly higher Q values in the UV region of excitation. We found that the quantum yield for CD luminescence is 4-8 times higher than that for CD-DND luminescence, and 20 times higher than that for DND luminescence. Roughly three spectral regions can be distinguished within the Q(λex): below 330 nm, 330-390 nm and 390-470 nm. Conclusions are drawn about the number of chromophores of the studied nanoparticles and transfer of photoexcitation energy in the systems under consideration.

Nanodiamonds and surfactants in water: Hydrophilic and hydrophobic interactions.

HYPOTHESIS: Nanodiamonds, one of the most promising nanomaterials for the use in biomedicine, placed in the organisms are bound to interact with various amphiphilic lipids and their micelles. However, while the influence of surfactants, the close relative of lipids, on the properties of colloidal nanodiamonds is well studied, the influence of nanodiamonds on the properties of surfactants, lipids, and, therefore, on the structure of surrounding tissues, is poorly understood. EXPERIMENT: In this work, the influence of interactions of hydrophobic and hydrophilic nanodiamonds with ionic surfactant sodium octanoate in water on hydrogen bonds, the properties of the surfactant and micelle formation were studied using Raman spectroscopy and dynamic light scattering technique. FINDINGS: Nanodiamonds are found to actively influence the bulk properties only of the premicellar surfactant solutions: the strength of hydrogen bonds, ordering and conformation of hydrocarbon tails, the critical micelle concentration. This influence is deduced to be dependent on two mechanisms not unique to nanodiamonds: (1) the induction of micro-flows around nanoparticles undergoing Brownian motions, and (2) the creation of the chaotic state in the surfactant solutions if two or more incompatible types of interactions between nanoparticles' surfaces and surfactants are similarly favorable, e.g. hydrophobic interaction and Coulomb attraction.

A method for optical imaging and monitoring of the excretion of fluorescent nanocomposites from the body using artificial neural networks.

In this study, a new approach to the implementation of optical imaging of fluorescent nanoparticles in a biological medium using artificial neural networks is proposed. The studies were carried out using new synthesized nanocomposites - nanometer graphene oxides, covered by the poly(ethylene imine)-poly(ethylene glycol) copolymer and by the folic acid. We present an example of a successful solution of the problem of monitoring the removal of nanocomposites based on nGO and their components with urine using fluorescent spectroscopy and artificial neural networks. However, the proposed method is applicable for optical imaging of any fluorescent nanoparticles used as theranostic agents in biological tissue.

Raman Spectroscopy of Water-Ethanol Solutions: The Estimation of Hydrogen Bonding Energy and the Appearance of Clathrate-like Structures in Solutions.

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.

Nanodiamond-Based Composite Structures for Biomedical Imaging and Drug Delivery.

Nanodiamond particles are widely recognized candidates for biomedical applications due to their excellent biocompatibility, bright photoluminescence based on color centers and outstanding photostability. Recently, more complex architectures with a nanodiamond core and an external shell or nanostructure which provides synergistic benefits have been developed, and their feasibility for biomedical applications has been demonstrated. This review is aimed at summarizing recent achievements in the fabrication and functional demonstrations of nanodiamond-based composite structures, along with critical considerations that should be taken into account in the design of such structures from a biomedical point of view. A particular focus of the review is core/shell structures of nanodiamond surrounded by porous silica shells, which demonstrate a remarkable increase in drug loading efficiency; as well as nanodiamonds decorated with carbon dots, which have excellent potential as bioimaging probes. Other combinations are also considered, relying on the discussed inherent properties of the inorganic materials being integrated in a way to advance inorganic nanomedicine in the quest for better health-related nanotechnology.

High-Pressure Synthesis of Boron-Doped Ultrasmall Diamonds from an Organic Compound.

The first application of the high-pressure-high-temperature (HPHT) technique for direct production of doped ultrasmall diamonds starting from a one-component organic precursor is reported. Heavily boron-doped diamond nanoparticles with a size below 10 nm are produced by HPHT treatment of 9-borabicyclo [3,3,1]nonane dimer molecules.

Functionalization of graphene oxide nanostructures improves photoluminescence and facilitates their use as optical probes in preclinical imaging.

Recently reported photoluminescent nanographene oxides (nGOs), i.e. nanographene oxidised with a sulfuric/nitric acid mixture (SNOx method), have tuneable photoluminescence and are scalable, simple and fast to produce optical probes. This material belongs to the vast class of photoluminescent carbon nanostructures, including carbon dots, nanodiamonds (NDs), graphene quantum dots (GQDs), all of which demonstrate a variety of properties that are attractive for biomedical imaging such as low toxicity and stable photoluminescence. In this study, the nGOs were organically surface-modified with poly(ethylene glycol)-poly(ethylene imine) (PEG-PEI) copolymers tagged with folic acid as the affinity ligand for cancer cells expressing folate receptors. The functionalization enhanced both the cellular uptake and quantum efficiency of the photoluminescence as compared to non-modified nGOs. The nGOs exhibited an excitation dependent photoluminescence that facilitated their detection with a wide range of microscope configurations. The functionalized nGOs were non-toxic, they were retained in the stained cell population over a period of 8 days and they were distributed equally between daughter cells. We have evaluated their applicability in in vitro and in vivo (chicken embryo CAM) models to visualize and track migratory cancer cells. The good biocompatibility and easy detection of the functionalized nGOs suggest that they could address the limitations faced with quantum dots and organic fluorophores in long-term in vivo biomedical imaging.

Liquid Polyamorphous Transition and Self-Organization in Aqueous Solutions of Ionic Surfactants.

Polyamorphous transitions in supercooled water, porous substances, solutions of polyols, and proteins are studied intensively. They accompany the self-organization of hydrocarbons and surfactants. In this study, the methods of polyamorphous transition identification are proposed, and their dependence on hydrocarbons and surfactant concentration and sizes is investigated. The place of polyamorphous transitions in the general theory of phase separation is determined, and their bistability, self-oscillations, hysteresis, fluctuations, cooperative effect, enthalpy, and entropy are described. Surface, volume, and diffusion instabilities of polyamorphous transitions are analyzed. Technologies based on the properties of polyamorphous transitions are proposed.

Optical imaging of fluorescent carbon biomarkers using artificial neural networks.

The principle possibility of extraction of fluorescence of nanoparticles in the presence of background autofluorescence of a biological environment using neural network algorithms is demonstrated. It is shown that the methods used allow detection of carbon nanoparticles fluorescence against the background of the autofluorescence of egg white with a sufficiently low concentration detection threshold (not more than 2 µg/ml for carbon dots 3 µg/ml and for nanodiamonds). It was also shown that the use of the input data compression can further improve the accuracy of solving the inverse problem by 1.5 times.

Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery II: application.

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.

Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery I: fabrication.

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.

Structurability: a collective measure of the structural differences in vodkas.

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.

Fluorescence diagnostics of oil pollution in coastal marine waters by use of artificial neural networks.

We discuss the problems with and the real possibilities of determining oil pollution in situ in coastal marine waters with fluorescence spectroscopy and of using artificial neural networks for data interpretation. In general, the fluorescence bands of oil and aquatic humic substance overlap. At oil concentrations in water from a few to tens of micrograms per liter, the intensity of oil fluorescence is considerably lower than that of humic substances at concentrations that typically are present in coastal waters. Therefore it is necessary to solve the problem of separating the small amount of oil fluorescence from the humic substance background in the spectrum. The problem is complicated because of possible interactions between the components and variations in the parameters of the fluorescence bands of humic substances and oil in water. Fluorescence spectra of seawater samples taken from coastal areas of the Black Sea, samples prepared in the laboratory, and numerically simulated spectra were processed with an artificial neural network. The results demonstrate the possibility of estimating oil concentrations with an accuracy of a few micrograms per liter in coastal waters also in cases in which the contribution from other organic compounds, primarily humic substances, to the fluorescence spectrum exceeds that of oil by 2 orders of magnitude and more.