Positioning metal-organic framework nanoparticles within the context of drug delivery - A comparison with mesoporous silica nanoparticles and dendrimers.

Nanotechnology enables the creation of delivery vehicles able to overcome physiologically imposed barriers, allowing new approaches for reducing the unwanted side effects of systemic delivery of drug, increasing targeting efficiency and so improving therapy efficacy. Owing to the considerable advances in material sciences and pharmaceutics, a broad range of different inorganic or organic drug nanocarriers have been developed. Furthermore, researchers have shown that the combination of inorganic and organic chemistries in one single material, named metal-organic framework (MOF), offers structural designability at the molecular level together with tunable porosity and chemical functionalisability.

Protoporphyrin IX-Functionalized AgSiO Core-Shell Nanoparticles: Plasmonic Enhancement of Fluorescence and Singlet Oxygen Production.

Metal-enhanced processes arising from the coupling of a dye with metallic nanoparticles (NPs) have been widely reported. However, few studies have simultaneously investigated these mechanisms from the viewpoint of dye fluorescence and photoactivity. Herein, protoporphyrin IX (PpIX) is grafted onto the surface of silver core silica shell NPs in order to investigate the effect of silver (Ag) localized surface plasmon resonance (LSPR) on PpIX fluorescence and PpIX singlet oxygen ( O ) production.

Compound droplet manipulations on fiber arrays.

Recent works demonstrated that fiber arrays may constitute new means of designing open digital microfluidic systems. Various processes, such as droplet motion, fragmentation, trapping, release, mixing and encapsulation, may be achieved on fiber arrays. However, handling a large number of tiny droplets resulting from the mixing of several liquid components is required for developing microreactors, smart sensors or microemulsifying drugs.

A one-step short-time synthesis of Ag@SiO2 core-shell nanoparticles.

A performance of shell-thickness precise control in silver-silica coating core-shell nanoparticles is presented. 60nm sized citrate-stabilized silver nanoparticles are directly silica coated using a modified Stöber process. Tetraethyl orthosilicate is used as a silica precursor and ammonium hydroxide as catalyst in an alcoholic solvent to promote the seeded silica growth.

Linear and nonlinear optical properties of functionalized CdSe quantum dots prepared by plasma sputtering and wet chemistry.

We develop an innovative manufacturing process, based on radio-frequency magnetron sputtering (RFMS), to prepare neat CdSe quantum dots (QDs) on glass and silicon substrates and further chemically functionalize them. In order to validate the fabrication protocol, their optical properties are compared with those of QDs obtained from commercial solutions and deposited by wet chemistry on the substrates. Firstly, AFM measurements attest that nano-objects with a mean diameter around 13 nm are located on the substrate after RFMS treatment.

Comparative study of Ag and Au nanoparticles biosensors based on surface plasmon resonance phenomenon.

The specific sensitivity of surface plasmon resonance to changes in the local environment of nanoparticles allows their use as platforms to probe chemical and biochemical binding events on their surfaces without any labeling [1-4]. In this paper, we perform a comparative study of gold and silver nanoparticle based biosensors, prepared within the same conditions, in order to determine which metal seems the best for biological sensing. The prototypical biocytin-avidin interaction is used to study gradual changes over time and with avidin concentration in the absorption spectra bands of biocytinylated 10 nm silver and gold nanospheres.

ESR technique for noninvasive way to quantify cyclodextrins effect on cell membranes.

A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of Randomly methylated-beta-cyclodextrin (Rameb) on living cells (HCT-116). The relative anisotropy observed in ESR spectrum of nitroxide spin probe (5-DSA and cholestane) is directly related to the rotational mobility of the probe, which can be further correlated with the microviscosity.

Turbidimetric and microscopic analysis of Bacteroides fragilis exposed to tazobactam and piperacillin alone and in combination.

Tazobactam, a non-amino penicillanic acid sulfone, is a new beta-lactamase inhibitor and acts synergistically with piperacillin against clinical isolates of beta-lactamase-producing Bacteroides fragilis. The effectiveness of this inhibitor has been demonstrated by reduction of piperacillin MIC values and growth curves in two combinations (ratio 8:1 and 4:1). Tazobactam has an intrinsic activity against B.

Bactericidal activity of meropenem against Pseudomonas aeruginosa.

Ten strains of Pseudomonas aeruginosa that were susceptible to imipenem (MICs 2 mg/l) were exposed to a new parenteral carbapenem, meropenem (MIC 0.25 mg/l). Kinetic turbidometry showed that, as with other beta-lactam antibiotics, there was a prelytic increase in the culture OD following exposure to meropenem.

Growth Curve Patterns of Escherichia coli, Serratia marcescens, and Proteus vulgaris Submitted to Different Tigemonam Concentrations.

Five strains of Escherichia coli, Serratia marcescens, and Proteus vulgaris were exposed to a new monobactam, tigemonam, in comparison with aztreonam. The study, evaluated by kinetic turbidimetry, has shown that tigemonam exerts a prelytic increase in optical density (OD) similar to that of other beta-lactam antibiotics. The maximal value of the prelytic increase in OD was similar for the two study antibiotics at concentrations of 1, 2, 4, and 8 times the minimum inhibitory concentration, corresponding with filament formation.

Growth curve patterns of Escherichia coli, Serratia marcescens, and Proteus vulgaris submitted to different tigemonam concentrations.

Five strains of Escherichia coli, Serratia marcescens, and Proteus vulgaris were exposed to a new monobactam, tigemonam, in comparison with aztreonam. The study, evaluated by kinetic turbidimetry, has shown that tigemonam exerts a prelytic increase in optical density (OD) similar to that of other beta-lactam antibiotics. The maximal value of the prelytic increase in OD was similar for the two study antibiotics at concentrations of 1, 2, 4, and 8 times the minimum inhibitory concentration, corresponding with filament formation.

Correlation between the growth and killing curves of Escherichia coli in the presence of cefotetan or piperacillin.

Escherichia coli strains that were susceptible to multiple antibiotics were exposed to cefotetan and piperacillin. As with the majority of beta-lactam antibiotics, the growth curves showed an increase in optical density (OD) due to an increasing volume of cell-wall-deficient bacteria during the first hours before lysis. This increase in OD depended on the concentration of cefotetan and was less dependent on the concentration of piperacillin.

Protective effect of amdinocillin against emergence of resistance to ceftazidime in Enterobacter cloacae.

Enterobacter cloacae infections have been shown clinically to respond less reliably to monotherapy with broad-spectrum cephalosporins than was initially expected. Selection of populations producing high levels of beta-lactamase has been shown to be the most frequent reason for treatment failure, and the use of these agents with another active antibiotic is recommended. In this study, E.

Rate of bactericidal activity for Branhamella catarrhalis of fleroxacin compared with that of amoxycillin-clavulanic acid.

The rate of bactericidal activity of fleroxacin was compared with that of the combination of amoxycillin and clavulanic acid (in the proportion of 4 to 1) on beta-lactamase producing strains of Branhamella catarrhalis. The rate of bactericidal activity of 1 mg/l was as rapid as that of 1 mg/l of amoxycillin-clavulanic acid combination. This rate was not significantly more rapid if the concentrations of fleroxacin were increased to 10 mg/l.

Determination of serum bactericidal activity against Escherichia coli by an automated photometric method.

The resistance of gram-negative bacteria to complement-mediated serum activity is supposedly an important virulence factor. However, the lack of standardization in the methods used to determine serum activity and the many definitions applied make the comparisons between studies very difficult. We developed a rapid photometric method that we compared with a classical killing one.

Bactericidal effect and regrowth of Streptococcus faecalis exposed to amoxicillin following beta-lactamase.

Streptococcus faecalis usually requires high concentrations of penicillin or ampicillin to achieve killing (i.e. a high MBC/MIC ratio).

Rate of bactericidal activity for Branhamella catarrhalis of a new macrolide, CP-62,993, compared with that of amoxicillin-clavulanic acid.

The rate of bactericidal activity of a new macrolide, CP-62,993, was compared with that of the combination of amoxicillin and clavulanic acid (in the proportion of 4 to 1) on strains of Branhamella catarrhalis beta-lactamase producers. The antibacterial activity of CP-62,993 was bacterostatic at 0.01 micrograms/ml.

[Measure by turbidimetry and bactericidal effect of the speed of action of clavulanic acid, amoxicillin and their combinations on a Haemophilus influenzae producer of beta-lactamase].

The amoxicillin-acid clavulanic acid combination is known to be active on H. influenzae beta-lactamase producer. Clavulanic acid possesses its own antibacterial activity at high concentrations.

Effect on growth curves and killing curves of brief exposure of Escherichia coli to imipenem and piperacillin.

Escherichia coli was exposed to various concentrations of imipenem and piperacillin. As with the majority of beta-lactam antibiotics, the kinetic turbidometric growth curves showed, during the first few hours, an increase in optical density (OD) before lysis. This increase in OD depended on the concentration of imipenem and was independent of the concentration of piperacillin.

Rate of bactericidal activity for Streptococcus faecalis of a new quinolone, CI-934, compared with that of amoxicillin.

The rate of bactericidal activity of a new quinolone, CI-934, was compared with that of amoxicillin for 20 strains of Streptococcus faecalis. At 10 and 100 micrograms/ml, the bactericidal activity of CI-934 was more rapid at 6 h than that of amoxicillin. A paradoxical effect (a killing rate higher at 1 microgram/ml than at 100 micrograms/ml at 6 h) was observed for 19 of the 20 strains with amoxicillin and for 1 of the 20 strains with CI-934.

[Growth curves and killing rate of Haemophilus influenzae exposed to amoxicillin, cefaclor and cefotaxime].

The antibacterial activity of beta-lactams against H. influenzae is difficult to evaluate as a result of the osmotic-pressure-dependent formation of filaments and spheroplasts whose viability is still under debate. We compared growth curves obtained by optic density measurements and by UFC/ml counts for H.

Effect of mecillinam on Escherichia coli growth curves when given alone and associated with ampicillin.

The effects on growth curves of strains of Escherichia coli by mecillinam, ampicillin, and combinations of the two antibiotics were investigated using the Abbott-MS-2 system. Maximal increase in optical density in the residual growth phase was found to be concentration dependent for ampicillin and nearly concentration independent for mecillinam. The addition of ampicillin potentiated the effect on mecillinam.

Correlation between growth curve and killing curve of Escherichia coli after a brief exposure to suprainhibitory concentrations of ampicillin and piperacillin.

Escherichia coli strains that were susceptible to multiple antibiotics were exposed to suprainhibitory concentrations of ampicillin and piperacillin. As with the majority of beta-lactam antibiotics, the growth curves showed an increase in optical density (OD) before lysis during the first hours. This increase in OD depended on the concentration of ampicillin and was independent of the concentration of piperacillin.