Florina Teodorescu

Nanodiamond–PMO for two-photon PDT and drug delivery

In this article, we highlight the properties of nanodiamonds (ND), which were encapsulated in periodic mesoporous organosilica nanoparticles (PMO) and were able to generate reactive oxygen species for photodynamic applications upon two-photon excitation (TPE). The ND@PMO nanoparticles were characterized by various techniques and were then loaded with the anti-cancer drug doxorubicin. The release of the drug was pH sensitive and a synergistic cancer cell killing effect was observed when cancer cells were incubated with doxorubicin-loaded ND@PMO and irradiated with two-photon excitation at 800 nm.

MoS2/reduced graphene oxide as active hybrid material for the electrochemical detection of folic acid in human serum.

In this study, a new matrix based on a molybdenum disulfide-reduced graphene oxide hybrid (MoS2-rGO) was prepared and characterized. Modification of a glassy carbon electrode (GCE) with MoS2-rGO (MG) using drop casting allowed for the selective analysis of folic acid in the presence of a variety of interference species with a limit of detection of 10nM, a linear range between 0.01μM and 100μM with a sensitivity of 14µAµM(-1). In addition, the analytical performance of the proposed sensor was successfully conducted for the determination of folic acid in human serum samples, making MG-GC electrodes promising interfaces for bio-electrochemical applications.

Transdermal skin patch based on reduced graphene oxide: A new approach for photothermal triggered permeation of ondansetron across porcine skin

&NA; The development of a skin‐mounted patch capable of controlled transcutaneous delivery of therapeutics through thermal activation provides a unique solution for the controlled release of active principles over long‐term periods. Here, we report on a flexible transdermal patch for photothermal triggered release of ondansetron (ODS), a commonly used drug for the treatment of chemotherapy‐induced nausea and vomiting and used as model compound here. To achieve this, a dispersion of ODS‐loaded reduced graphene oxide (rGO‐ODS) nanosheets were deposited onto Kapton to produce a flexible polyimide‐based patch. It is demonstrated that ODS loaded Kapton/rGO patches have a high drug delivery performance upon irradiation with a continuous laser beam at 980 nm for 10 min due to an induced photothermal heating effect. The ability of ODS impregnated Kapton/rGO patches as transdermal delivery scaffolds for ODS across the skin is in addition investigated using porcine ear skin as a model. We show that the cumulative quantity and flux of ODS passing the skin are highly depending on the laser power density used. At 5 W cm− 2 irradiation, the ODS flux across pig skin was determined to be 1.6 &mgr;g cm− 2 h− 1 comparable to other approaches. The use of tween 20 as skin enhancer could significantly increase the ODS flux to 13.2 &mgr;g cm− 2 h− 1. While the skin penetration enhancement is comparable to that obtained using other well‐known permeation enhancers, the actual superiority and interest of the proposed approach is that the Kapton/rGO photoactivatable skin patch can be loaded with any drugs and therapeutics of interest, making the approach extremely versatile. The on demand delivery of drugs upon local laser irradiation and the possibility to reload the interface with the drug makes this new drug administration route very appealing. Graphical abstract Figure. No caption available.

Photothermally triggered on-demand insulin release from reduced graphene oxide modified hydrogels

Abstract On‐demand delivery of therapeutics plays an essential role in simplifying and improving patient care. The high loading capacity of reduced graphene oxide (rGO) for drugs has made this matrix of particular interest for its hybridization with therapeutics. In this work, we describe the formulation of rGO impregnated poly(ethylene glycol) dimethacrylate based hydrogels (PEGDMA‐rGO) and their efficient loading with insulin. Near‐infrared (NIR) light induced heating of the PEGDMA‐rGO hydrogels allows for highly efficient insulin release. Most importantly, we validate that the NIR irradiation of the hydrogel has no effect on the biological and metabolic activities of the released insulin. The ease of insulin loading/reloading makes this photothermally triggered release strategy of interest for diabetic patients. Additionally, the rGO‐based protein releasing platform fabricated here can be expanded towards ‘on demand’ release of various other therapeutically relevant biomolecules. Graphical abstract The table of contents entry: Poly(ethylene glycol) based hydrogels impregnated with rGO allow efficient loading and ‘on demand’ photothermal release of insulin while preserving its biological and metabolic activity. Figure. No Caption available.

Conformational equilibria of TADDOL-s in solution investigated by vibrational circular dichroism.

Six enantiomeric pairs of TADDOL-s gathered in two series with either methyl (series A) or phenyl (series B) substituent in 2-position of the dioxolane ring were studied by vibrational circular dichroism (VCD). Experimental IR and VCD spectra associated with density functional theory (DFT) calculations showed that the two series exhibit quite different conformations in solution. In series A, the conformer with anti C-O bonds and stabilized by intramolecular OH...OH hydrogen bonding prevails, whereas in series B the conformer with gauche C-O bonds and intramolecular OH...π hydrogen bonding is favored. The shape and sign of the VCD bands in the O-H stretching region revealing the nature of the intramolecular hydrogen bonding were clearly identified. Polarimetric measurements showed that, within the same absolute configuration, compounds in series A and in series B have opposite signs of optical rotation.

New highlights of the syntheses of pyrrolo(1,2-a)quinoxalin-4-ones

Summary The one-pot three-component reactions of 1-substituted benzimidazoles with ethyl bromoacetate and electron-deficient alkynes, in 1,2-epoxybutane, gave a variety of pyrrolo[1,2-a]quinoxalin-4-ones and pyrrolo[1,2-a]benzimidazoles. The influence of experimental conditions on the course of reaction was investigated. A novel synthetic pathway starting from benzimidazoles unsubstituted at the five membered ring, alkyl bromoacetates and non-symmetrical electron-deficient alkynes in the molar ratio of 1:2:1, in 1,2-epoxybutane at reflux temperature, led directly to pyrrolo[1,2-a]quinoxalin-4-ones in fair yield by an one-pot three-component reaction.

Effects of dopants and oxygen non-stoichiometry on thermodynamic and magnetic properties of micro- and nanostructured perovskite type manganites

Abstract The aim of the paper is to evidence the effect of the composition and oxygen stoichiometry on the thermodynamic, spin dynamics and magnetic properties of some micro- and nanostructured substituted manganites La1–xAxMn1–yByO3–δ (A=Ca; B=Co, Fe; x=0·33; y=0, 0·02 and 0·04). The partial molar thermodynamic properties of oxygen dissolution in the perovskite phase as well the equilibrium partial pressures of oxygen have been obtained using solid electrolyte electrochemical cells [electromotive force measurement (EMF)] method. The influence of the oxygen stoichiometry change on the thermodynamic properties was examined using the data obtained by a coulometric titration technique coupled with EMF measurements. Using electron paramagnetic resonance spectroscopy, the spin dynamics has been investigated. Particular attention was devoted to the discussion concerning the influence of doping on polaron activation energy E a and exchange coupling integral J between Mn spins. The results were correlated with the variation of both saturation magnetisation M s and Curie temperature T c. The data were discussed in relation to significant changes in the overall concentration of defects. New features related to the modifications in properties connected with the nanocrystalline state were evidenced.

Advancements on the molecular design of nanoantibiotics: current level of development and future challenges

Numerous antimicrobial drugs have been developed and commercialized to kill and inhibit the growth of pathogenic microbes. The therapeutic efficiency of these drugs has however become often inadequate for the treatment of microbial infections, the reasons being multiple. Oral administration results often in only partial absorption and up to 50% of the active compound can be excreted in the urine. Furthermore, antibiotic therapy is also frequently accompanied by gastrointestinal complications, including vomiting, nausea and diarrhea. From a therapeutic point of view, the low solubility of antibiotics in lipid membranes presents a limitation for rapid and efficient treatment of infections. The preferred route for the delivery of antimicrobial drugs is the oral one; oral formulations capable of extending the duration of drug delivery and minimizing side effects have received much attention. The combination of antimicrobial agents with nanomaterials has been seen as a particularly promising strategy to overcome these limitations. Particulate formulations have proven their efficiency in achieving better pharmacokinetic profiles and improving the bio availability of several antibiotics. Antibiotic modified particles have shown their capability to protect some of the antimicrobial drugs from stomach acid and first-pass metabolisms in the gastrointestinal tract. Likewise, particle formulations can increase the circulation times of a drug and the local concentration gradient across absorptive cells. The present review describes the current status of different types of antibiotic loaded nano-systems. Key principles such as antibiotic loading, the release mechanism and the mode of action involved in pathogen killing or inhibition will be discussed in more detail. It is hoped that the general knowledge obtained here will help in the generation of advanced nanomaterials loaded with antimicrobials agents.

Low-Temperature synthesis and thermodynamic and electrical properties of barium titanate nanorods

Studies regarding the morphology dependence of the perovskite-type oxides functional materials properties are of recent interest. With this aim, nanorods (NRs) and nanocubes (NCs) of barium titanate (BaTiO3) have been successfully synthesized via a hydrothermal route at temperature as low as 408 K, employing barium acetate, titanium isopropoxide, and sodium hydroxide as reagents without any surfactant or template. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD), used for the morphology and structure analyses, showed that the NRs were formed by an oriented attachment of the NCs building-blocks with 20 nm average crystallites size. The thermodynamic properties represented by the relative partial molar free energies, enthalpies, and entropies of the oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressure of oxygen, indicated that NRs powders have lower oxygen vacancies concentration than the NCs. This NRs characteristic, together with higher tetragonallity of the structure, leads to the enhancement of the dielectric properties of BaTiO3 ceramics. The results presented in this work show indubitably the importance of the nanopowders morphology on the material properties.