The present study focuses on the design, production and characterization of lipid-based nanosystems as a tool to deliver manganese for diagnostic purpose in multimodal imaging techniques. Particularly, aqueous dispersions of anionic liposomes have been considered as delivery systems for different manganese-based compounds. Negatively charged liposomes were obtained by direct hydration method followed by extrusion using in their composition different anionic surfactants, such as N-lauroylsarcosine (NLS) and sodium lauroyl lactylate (SLL). After production, liposomes were characterized in terms of size, polydispersity, surface charge and stability over time. The extruded liposome dispersions were homogeneous, monodispersed (with an average diameter not exceeding 200 nm) and negatively charged as confirmed by ζ potential measurement. Moreover, as indicated by atomic absorption spectroscopy analyses, the loading of manganese-based compounds was almost quantitative. Liposomes composed of NLS or SLL were stable over time and the presence of manganese-based compounds did not affect their size distribution. In addition their magnetic properties have been retained. The in vitro cytotoxicity of the prepared anionic liposomes was evaluated by MTT assay on human keratinocyte. The obtained results highlighted that unloaded formulations and liposomes loaded with hydrophilic manganese derivatives do not affect cell viability, while liposomes loaded with lipophilic manganese derivatives showed a dose-dependent antiproliferative effect. Therefore further experiments need to be performed in order to elucidate the optimal type and concentration of manganese derivative evaluating both the loading capacity and its bioavailability possibly using other non-tumor human cell lines, such as fibroblasts.

Exceptional points have been studied in a plethora of classical optical systems and can dramatically modify the optical response of the studied system. Recently, there is increasing interest in applying the exceptional points formalism in fully quantum systems to achieve efficient control at the quantum level and show the drastic effect exceptional points have on the system's properties. In this work, we theoretically study the effect of quantum exceptional points on the optical properties of a quantum dot placed inside an optical microcavity and interacting with a weak probe field. For the analysis of the system, we use a quantum approach, where we model the quantum dot as a two-level system and describe the light-matter interaction with the proper master equation, including the spontaneous decay and the pure dephasing of the quantum dot, as well as the decay of the optical cavity. We also define the effective non-Hermitian Hamiltonian of the system and derive the necessary conditions for the formation of an exceptional point, the point where the eigenvalues of the Hamiltonian coalesce. We then study the steady state behavior of the system and calculate the optical susceptibility from the coherences between the vacuum and the system. By separating the total susceptibility to two equivalent susceptibilities, corresponding to fictitious free quantum emitters, we show exceptional points drastic effect to the optical properties of the system close to the region where the exceptional point is formed. We further examine the optical properties of the system in the regions of the parameter space that arise from the exceptional condition, namely the strong (coherent) coupling regime and the weak (incoherent) coupling regime.

We study the spontaneous emission (SE) dynamics of a QE near a graphene nanodisk. We analyze the excited state population dynamics, quantify its features using different non-Markovianity measures, compute the quantum speed limit of the dynamics, which can be achieved under the given coupling conditions. More specifically, we investigate the SE dynamics of the excited state population of a QE modelled as a two-level system located at 5 nm and 15 nm from a graphene nanodisk of radius 30 nm, while the free-space decay time of the emitter lies between hundred picoseconds and microseconds. At close distance and for short free-space decay times of the QE, the observed dynamics shows strong non-Markovian features; as the distance from the nanodisk or the free-space decay time increases, the non-Markovian features in the dynamics diminish. These findings reflect the transition from strong light-matter coupling to weak coupling conditions. Under strong coupling conditions, we also observe pronounced decaying Rabi oscillations and population trapping effects in the excited state population dynamics of the QE. We also quantify the non-Markovianity of the SE dynamics by computing different measures and the quantum speed limit for each case, obtaining large measures values and potentially large quantum speed-up for the dynamics under such coupling conditions, while both properties are decreasing as the coupling weakens. These results and the observations related to the QE excited state population dynamics under strong coupling conditions are in agreement. Evidently, the graphene nanodisk can become a platform for achieving strong coupling conditions for light-matter interaction at the nanoscale even for large free-space decay times and at large distances between the quantum emitter and the nanophotonic structure in comparison to metallic nanoparticles.

Dithiocarbazates comprise an important class of Schiff bases that have remarkable pharmacological applications due to the imine group present in their structure^1,2,3. However, the lipophilic character of 1-(S-benzyldithiocarbazate)-3-methyl-5-phenyl-pyrazole (DTC) limits its gastrointestinal absorption leading to low oral bioavailability. This problem can be solved using DTC-loaded nanoparticles, such as mesoporous silica nanoparticles (MSiNP), synthesized by Stöber method, which allows controlling the pores, walls and surfaces, facilitating the incorporation of several complex organic groups⁴. In this sense, the present work reports the loading of DTC in MSiNP aiming at potential application in drug delivery and targeting. The results indicated that MSiNP-DTC presented good stability in suspension, exhibiting Z-Ave of 175.7 ± 0.9, PdI of 0.38 ± 0.04 nm and ZP values ​​of – 21.9 ± 0.33 mV. The TEM image showed the mesoporous structure of the silica nanoparticles and also revealed no influence on the size, shape and morphology of MSiNP after its surface modification with DTC. The main band of DTC in FT-IR was shifted in relation to MSiNP appearing at 1627 cm^-1 (vibration band ν(C=N)). Thermal analysis showed an endothermic peak around 104℃ which is indicative of a crystalline state of the drug, confirming DTC loading on MSiNP. The percentage of drug loading (DL) and encapsulation efficacy (EE) were 9.9 ± 0.0001% and 99.3 ± 0.002%, respectively. This high efficiency can be explained based on the results of the BET which had a significant decrease in the specific surface area and MSiNP-DTC volume (617.9 ± 15.3 m²/g and 1.01 ± 0.01 cm³/g) and an increase in pore size (6.5 ± 0.1 nm), suggesting a pore blockage, leading DTC to adhere to the MSiNP surface. Therefore, the data suggest that MSiNP-DTC has potential for the use in drug delivery applications, improving stability and overcoming the low water solubility of Schiff's dithiocarbazate bases.

1. Costa, R. de O.; Coutinho, J. P. Use of Mixture Design to Optimize Nanofabrication of Dithiocarbazate–Loaded Polylactic Acid Nanoparticles. J. Appl. Polym. Sci. 2022, 139 (3), 1–13.
2. de Menezes, T. I.; de Oliveira Costa. Preparation and Characterization of Dithiocarbazate Schiff Base–Loaded Poly(Lactic Acid) Nanoparticles and Analytical Validation for Drug Quantification. Colloid Polym. Sci. 2019, 297 (11–12), 1465–1475.
3. Costa, A. R.; de Menezes, T. I. Ruthenium(II) Dimethylsulfoxide Complex with Pyrazole/Dithiocarbazate Ligand: Synthesis, Spectroscopy Studies, DFT Calculations and Thermal Behavior. J. Therm. Anal. Calorim. 2019, 0123456789 (Ii), 1683–1696.
4. Paula, A. J.; Martinez, D. S.T. Suppression of the Hemolytic Effect of Mesoporous Silica Nanoparticles after Protein Corona Interaction: Independence of the Surface Microchemical Environment. J. Braz. Chem. Soc. 2012, 23 (10), 1807–1814.

Carbon nanotubes (CNTs) represent a unique class of nanomaterials with remarkable applications in diverse domains. However, one of the many challenges still requiring improvements is undoubtedly their dispersion stability. The control of the dispersion stability of CNTs is still a challenge due to the strong of van der Waals forces that lead to their aggregation.
Metallic nanoparticles, such as silver (AgNPs), with the presence of a capping agent, e.g. PVP, are recognized as having an important role in the increase of the stability of nanoparticle dispersions, and if incorporated in the multi-walled carbon nanotubes (MWCNTs), may help surpass the MWCNTs aggregation problem.
The present work reports the enhancement of the stability of MWCNTs upon decoration by AgNPs, using an electrochemical method to generate the silver ions and promote the electro-deposition of silver.
To validate the increase in stability of the Ag decorated MWCNTs, two solvents were used in this study, water and glyceline, a eutectic mixture of choline chloride and glycerol.
The time stability of bare MWCNTs and AgMWCNTs nanofluids were characterized through DLS and UV-Vis.
Compared to commercial MWCNTs, MWCNTs decorated with AgNPs presented a significant stability enhancement, in both water and glyceline. Glyceline also presented a higher stability over time, with a retention of the UV-Vis absorbance up to 97%, compared to 50% for water media. The DLS analysis showed a standard deviation minimum value of ~7 nm, in glyceline, and ~50 nm, in water. In both cases, the use of AgMWCNTs materials improved the stability of the dispersions 25x in glyceline and 2.5x in water, when compared to the stability of bare MWCNTs dispersions.

Thermal losses significantly affect the performance efficiency of solar devices, electronic circuits, building materials, air conditioners, refrigerators, etc. Improving thermal buffering capacity is the remedy for this problem. It is achieved by incorporating phase change materials (PCMs). PCMs can absorb, accumulate, or emit latent heat during the phase transition process at a specific temperature range, making them suitable for thermal energy storage. However, PCMs have two major drawbacks which need to be rectified before use. The first disadvantage is leakage of molten PCM, and the second is low thermal conductivity. Both problems can be resolved by preparing PCM nanocomposites. The strategies of nanocomposite preparation can be briefly classified into three methods, namely blending, encapsulation and impregnation. The review paper discusses the effect of nanomaterial morphology on the form-stabilization of PCM. The nanomareials can modify thermal conductivity, electrical conductivity, and mechanical properties as per application requirements. This article highlights the benefits of using thermal energy storing nanocomposites in widely used application areas such as textiles, building materials, electronics systems, and solar energy storage devices. They can also be utilized for niche applications such as shape memory polymers and infrared thermal stealth.

Beeswax is a bio-based organic phase change material. It undergoes solid to liquid phase transition at 61 ⁰C with the phase transition enthalpy of 216 J/g. The high thermal energy storage enthalpy of beeswax is suitable for maintaining constant temperature. However, the low thermal conductivity of beeswax limits the heat transfer rate. Also, beeswax should be form-stabilized to minimize leakage in the molten state. In this study, the thermal conductivity of beeswax was improved with carbon nanotube (CNT) incorporation. The leakage of molten beeswax was minimized by blending it with recycled paperboard. The beeswax-CNT-recycled paperboard nanocomposite was further coated with silicone adhesive. It ensured the retention of molten wax. Taguchi method was applied to obtain optimum constituent concentration in the nanocomposite. FTIR spectrum and SEM morphology of nanocomposite confirm physical dispersion of CNT into the fibrous matrix. DSC analysis of nanocomposites showed reduction of TES enthalpy to 98.52 J/g. The improved heat transfer rate of nanocomposite was confirmed with a special test of back surface heating.

Gold nanoclusters (AuNCs) with diameter less than 2 nanometres have fluorescent properties. These nanoclusters can be prepared by microwave assisted synthesis using BSA (bovine serum albumin) as a template (1). During the synthesis, Au(III) ions are reduced to Au(I) or Au(0) which are bonded to BSA forming thus Au(I)-BSA complexes and/or AuNCs-BSA, respectively. Here, femtosecond stimulated Raman spectroscopy (FSRS), an ultrafast nonlinear optical technique is used to study vibrational structure of Au(I)-BSA complexes and AuNCs-BSA. FSRS has time resolution comparable to the vibrational period of molecular movements (ps to fs) and energy resolution less than 10 cm^-1. Three laser pulses are exploited in a typical FSRS experiment: actinic pulse, Raman pulse and probe pulse (2). According to our preliminary results, FSRS represents a very promising tool in the investigation of Au(I)-BSA complexes and AuNCs-BSA systems.

This research was funded by Grant Agency of the Czech Republic, grant number 19-03207S.

References:

(1) P. Andrýsková et al., The effect of fatty acids and BSA purity on synthesis and properties of fluorescent gold nanoclusters. Nanomaterials 2020, 10, 343; doi:10.3390/nano10020343

(2) Kukura P. et al. Femtosecond Stimulated Raman Spectroscopy. Annu. Rev. Phys. Chem. 2007. 58:461–88

Despite recent significant progress in the synthesis of new polymeric materials for solar cells (SCs), the mechanism of conduction in such SCs has not been fully elucidated.

In this work we apply the Kohn-Sham density functional theory (B3LYP / 6-31G**) to study the electronic and spatial structure of the 3,4-ethylenedioxythiopehene oligomer (SCs often use the complex salt of poly-3,4-ethylenedioxythiophene with polystyrenesulfonic acid) consisting of its 12 units (E12), in its various charge states: 0, +1, +2, +3, and +4. The doping extent is thus simulated by the charge increase of the corresponding oligomer species. We employed spin-unrestricted calculations (UB3LYP) for charge states +1 and +3.

The HOMO-LUMO gap in the neutral E12 amounts 2.06 eV. As the positive charge (as a model for an increasing doping extent) grows, we observe a progressive appearance of one (E12⁺¹), two (E12⁺²), three (E12⁺³), and four (E12⁺⁴) polaron levels within the abovementioned HOMO-LUMO gap. A single polaron level in E12⁺¹ is separated from the top of the valence band by 0.54 eV. Two polaron levels in E12⁺² are separated from the valence and conduction bands by 0.50 eV. In the cation E12⁺³, two polaron levels are separated from the top of the valence band by 0.8 eV, and the third level is situated 0.90 eV below the bottom of the conduction band. Finally, four polaron levels of E12⁺⁴, build pairwise a prototype of the polaron band within the HOMO-LUMO gap.

Thus, according to our model, the conductivity of a highly doped (oxidized) 3,4-ethylenedioxythiopehene oligomer consisting of its 12 units is provided by two polarons situated at the ends of the chain. For other oligomers, as well as for poly(3,4-ethylenedioxythiopehene), more sophisticated polaron structures might act as charge carriers.

The development of advanced compositions that combine high stability and tunable activity is a forefront trend in modern interdisciplinary science. This important scientific problem is solved by the formation of plasmonic nanostructures embedded in the structure of the adaptive organic matrix of natural polysaccharides. This makes it possible to obtain unique materials with the possibility of optimization for specific tasks both at the stage of synthesis and when used due to the excitation of plasmon resonance of inorganic architecture by external light. We report the results of the study of physicochemical and structural features of composites depending on trigger factors (i.e. pH), the change of which leads to conformational transformations of macromolecules. Considering a nanocoposite as molecular nanobot, - “…autonomic preprogrammed structure of atomic level…”, opens the way to design an adaptive natural nanomachine, the properties of which can be controlled by external influences.