Antimicrobial Effect and Cytotoxic Evaluation of Mg-Doped Hydroxyapatite Functionalized with Au-Nano Rods

Hydroxyapatite (HA) is the main inorganic mineral that constitutes bone matrix and represents the most used biomaterial for bone regeneration. Over the years, it has been demonstrated that HA exhibits good biocompatibility, osteoconductivity, and osteoinductivity both in vitro and in vivo, and can be prepared by synthetic and natural sources via easy fabrication strategies. However, its low antibacterial property and its fragile nature restricts its usage for bone graft applications. In this study we functionalized a MgHA scaffold with gold nanorods (AuNRs) and evaluated its antibacterial effect against S. aureus and E. coli in both suspension and adhesion and its cytotoxicity over time (1 to 24 days). Results show that the AuNRs nano-functionalization improves the antibacterial activity with 100% bacterial reduction after 24 h. The toxicity study, however, indicates a 4.38-fold cell number decrease at 24 days. Although further optimization on nano-functionalization process are needed for cytotoxicity, these data indicated that Au-NRs nano-functionalization is a very promising method for improving the antibacterial properties of HA.     

Targeted Hybrid Nanocarriers as a System Enhancing the Skin Structure

The skin is constantly exposed to external and internal factors that disturb its function. In this work, two nanosystems-levan nanoparticles and a surfactin-stabilized nanoemulsion were preserved (tested for microbial growth) and characterized (size, polydispersity, Zeta potential, and stability). The nanosystems were introduced in the model formulations-cream, tonic, and gel, and confirmed by TEM. The analysis showed that nanoemulsion has a spherical morphology and size 220–300 nm, while levan nanoparticles had irregular shapes independently of the use of matrix and with particle size (130–260 nm). Additionally, we examined the antiradical effect of levan nanoparticles and nanoemulsion in the prototype of formulations by scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl; EPR spectroscopy). The model cream with both nanosystems and the whole range of products with nanosystems were evaluated in vivo for hydration, elasticity, smoothness, wrinkles and vascular lesions, discoloration, respectively. The cream improved skin condition in all tested parameters in at least 50% of volunteers. The use of more comprehensive care, additionally consisting of a tonic and gel, reduced the previously existing skin discoloration to 10.42 ± 0.58%. The presented prototype formulations are promising in improving skin conditions.     

Exploring the Interplay between Drug Release and Targeting of Lipid-Like Polymer Nanoparticles Loaded with Doxorubicin

Targeted delivery of doxorubicin still poses a challenge with regards to the quantities reaching the target site as well as the specificity of the uptake. In the present approach, two colloidal nanocarrier systems, NanoCore-6.4 and NanoCore-7.4, loaded with doxorubicin and characterized by different drug release behaviors were evaluated in vitro and in vivo. The nanoparticles utilize a specific surface design to modulate the lipid corona by attracting blood-borne apolipoproteins involved in the endogenous transport of chylomicrons across the blood–brain barrier. When applying this strategy, the fine balance between drug release and carrier accumulation is responsible for targeted delivery. Drug release experiments in an aqueous medium resulted in a difference in drug release of approximately 20%, while a 10% difference was found in human serum. This difference affected the partitioning of doxorubicin in human blood and was reflected by the outcome of the pharmacokinetic study in rats. For the fast-releasing formulation NanoCore-6.4, the AUC_0→1h was significantly lower (2999.1 ng × h/mL) than the one of NanoCore-7.4 (3589.5 ng × h/mL). A compartmental analysis using the physiologically-based nanocarrier biopharmaceutics model indicated a significant difference in the release behavior and targeting capability. A fraction of approximately 7.310–7.615% of NanoCore-7.4 was available for drug targeting, while for NanoCore-6.4 only 5.740–6.057% of the injected doxorubicin was accumulated. Although the targeting capabilities indicate bioequivalent behavior, they provide evidence for the quality-by-design approach followed in formulation development.     

Formulation of Cannabidiol in Colloidal Lipid Carriers

In this study, the general processability of cannabidiol (CBD) in colloidal lipid carriers was investigated. Due to its many pharmacological effects, the pharmaceutical use of this poorly water-soluble drug is currently under intensive research and colloidal lipid emulsions are a well-established formulation option for such lipophilic substances. To obtain a better understanding of the formulability of CBD in lipid emulsions, different aspects of CBD loading and its interaction with the emulsion droplets were investigated. Very high drug loads (>40% related to lipid content) could be achieved in emulsions of medium chain triglycerides, rapeseed oil, soybean oil and trimyristin. The maximum CBD load depended on the type of lipid matrix. CBD loading increased the particle size and the density of the lipid matrix. The loading capacity of a trimyristin emulsion for CBD was superior to that of a suspension of solid lipid nanoparticles based on trimyristin (69% vs. 30% related to the lipid matrix). In addition to its localization within the lipid core of the emulsion droplets, cannabidiol was associated with the droplet interface to a remarkable extent. According to a stress test, CBD destabilized the emulsions, with phospholipid-stabilized emulsions being more stable than poloxamer-stabilized ones. Furthermore, it was possible to produce emulsions with pure CBD as the dispersed phase, since CBD demonstrated such a pronounced supercooling tendency that it did not recrystallize, even if cooled to −60 °C.     

Preparation of Co-Processed Excipients for Controlled-Release of Drugs Assembled with Solid Lipid Nanoparticles and Direct Compression Materials

The purpose of the study was to develop a novel, directly compressible, co-processed excipient capable of providing a controlled-release drug system for the pharmaceutical industry. A co-processed powder was formed by adsorption of solid lipid nanoparticles (SLN) as a controlled-release film onto a functional excipient, in this case, dicalcium phosphate dihydrate (DPD), for direct compression (Di-Tab^®). The co-processed excipient has advantages: easy to implement; solvent-free; industrial scaling-up; good rheological and compressibility properties; and the capability to form an inert platform. Six different batches of Di-Tab^®:SLN weight ratios were prepared (4:0.6, 3:0.6, 2:0.6, 1:0.6, 0.5:0.6, and 0.25:0.6). BCS class III ranitidine hydrochloride was selected as a drug model to evaluate the mixture’s controlled-release capabilities. The co-processed excipients were characterized in terms of powder rheology and dissolution rate. The best Di-Tab^®:SLN ratio proved to be 2:0.6, as it showed high functionality with good flow and compressibility properties (Carr Index = 16 ± 1, Hausner Index = 1.19 ± 0.04). This ratio could control release for up to 8 h, so it fits the ideal profile calculated based on biopharmaceutical data. The compressed systems obtained using this powder mixture behave as a matrix platform in which Fickian diffusion governs the release. The Higuchi model can explain their behavior.     

Synthesis and Characterization of Ligand-Linked Pt Nanoparticles: Tunable,Three-Dimensional,Porous Networks for Catalytic Hydrogen Sensing

Porous networks of Pt nanoparticles interlinked by bifunctional organic ligands have shown high potential as catalysts in micro-machined hydrogen gas sensors. By varying the ligand among p-phenylenediamine, benzidine, 4,4‘‘-diamino-p-terphenyl, 1,5-diaminonaphthalene, and trans-1,4-diaminocyclohexane, new variants of such networks were synthesized. Inter-particle distances within the networks, determined via transmission electron microscopy tomography, varied from 0.8 to 1.4 nm in accordance with the nominal length of the respective ligand. While stable structures with intact and coordinatively bonded diamines were formed with all ligands, aromatic diamines showed superior thermal stability. The networks exhibited mesoporous structures depending on ligand and synthesis strategy and performed well as catalysts in hydrogen gas microsensors. They demonstrate the possibility of deliberately tuning micro- and mesoporosity and thereby transport properties and steric demands by choice of the right ligand also for other applications in heterogeneous catalysis.     

Effect of Manganese Valence on Specific Capacitance in Supercapacitors of Manganese Oxide Microspheres

Manganese oxides have attracted great interest in electrochemical energy storage due to high theoretical specific capacitance and abundant valence states. The multiple valence states in the redox reactions are beneficial for enhancing the electrochemical properties. Herein, three manganese microspheres were prepared by a one-pot hydrothermal method and subsequent calcination at different temperatures using carbon spheres as templates. The trivalent manganese of Mn₂O₃ exhibited multiple redox transitions of Mn³⁺/Mn²⁺ and Mn⁴⁺/Mn³⁺ during the intercalation/deintercalation of electrolyte ions. The possible redox reactions of Mn₂O₃ were proposed based on the cyclic voltammetry and differential pulse voltammogram results. Mn₂O₃ microsphere integrated the advantages of multiple redox couples and unique structure, demonstrating a high specific capacitance and long cycling stability. The symmetric Mn₂O₃//Mn₂O₃ device yielded a maximum energy density of 29.3 Wh kg⁻¹ at 250 W kg⁻¹.     

Tracking the Electrocatalytic Activity of a Single Palladium Nanoparticle for the Hydrogen Evolution Reaction

The nanoparticle-based electrocatalysts’ performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre-sized electrode for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2–5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs’ electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency.     

Hybrid EuIII Coordination Luminophore Standing on Two Legs on Silica Nanoparticles for Enhanced Luminescence

In this study, we have demonstrated a two-legged, upright molecular design method for monochromatic and bright red luminescent Ln^III-silica nanomaterials. A novel Eu^III-silica hybrid nanoparticle was developed by using a doubly binding TPPO−Si(OEt)₃ (TPPO: triphenyl phosphine oxide) linker. The TPPO−Si(OEt)₃ was confirmed by ¹H, ³¹P, ²⁹Si NMR spectroscopy and single-crystal X-ray analysis. Luminescent Eu(hfa)₃ and Eu(tfc)₃ moieties (hfa: hexafluoroacetylacetonate, tfc: 3-(trifluoromethylhydroxymethylene)camphorate) were fixed onto TPPO−Si(OEt)₃-modified silica nanoparticles, producing Eu(hfa)₃(TPPO−Si)₂-SiO₂ and Eu(tfc)₃(TPPO−Si)₂-SiO₂, respectively. Eu(hfa)₃(TPPO−Si)₂−SiO₂ exhibited the higher intrinsic luminescence quantum yield (93 %) and longer emission lifetime (0.98 ms), which is much larger than those of previously reported Eu^III-based hybrid materials. Eu(tfc)₃(TPPO−Si)₂−SiO₂ showed an extra-large intrinsic emission quantum yield (54 %), although the emission quantum yield for the precursor Eu(tfc)₃(TPPO−Si(OEt)₃)₂ was found to be 39 %. These results confirmed that the TPPO−Si(OEt)₃ linker is a promising candidate for development of Eu^III-based luminescent materials.     

Multiple Regulation Effects of Ammonium Acetate on ZnO Growth Process in Chemical Bath Deposition

Chemical bath deposition method has been used to synthesize a variety of ZnO morphology structures. However, the specificity and interaction of acetate and ammonium ions with ZnO crystal during the growth process remain elusive. This study contributes to understand the roles of ammonium acetate on the growth mechanism of ZnO in Zn(NO₃)₂-HMTA system. The growth process indicates that the nucleation experienced Zn²⁺-layered basic zinc salts (LBZs)-ZnO process, while the self-assembled unit changed from urchin-shaped, rod-shaped to a fully coupled twin-shaped structure with increasing ammonium acetate concentration. Ammonium acetate dominates the growth process by combing the ligand-ligand interaction of acetate ions binding to the same Zn-rich (0001) polar surface and ammonium ions regulating hexamethylenetetramine (HMTA) hydrolysis. Relatively regular hexagonal wurtzite structure and a dissolve-renucleation-regrowth process which retains the twin-shaped template and renucleates at the same position are observed at ∼10 mM ammonium acetate. Photoelectrochemistry (PEC) measurements show that the uniform hexagonal ZnO rods (Y-10, the sample named as Y-x (x represents x mM ammonium acetate, herein, x is 10 mM)) have a maximum photocurrent density of 1.54 mA cm⁻² at 1.23 V (vs. RHE), much higher than that of the dumbbell-shaped ZnO rods (Y-50, 0.20 mA cm⁻²) at the same voltage. These results provide a further explanation of morphology regulation mechanisms on ZnO synthesis processes and pave the road for more practical applications.