The polyol process: a unique method for easy access to metal nanoparticles with tailored sizes, shapes and compositions

After about three decades of development, the polyol process is now widely recognized and practised as a unique soft chemical method for the preparation of a large variety of nanoparticles which can be used in important technological fields. It offers many advantages: low cost, ease of use and, very importantly, already proven scalability for industrial applications. Among the different classes of inorganic nanoparticles which can be prepared in liquid polyols, metals were the first reported. This review aims to give a comprehensive account of the strategies used to prepare monometallic nanoparticles and multimetallic materials with tailored size and shape. As regards monometallic materials, while the preparation of noble as well as ferromagnetic metals is now clearly established, the scope of the polyol process has been extended to the preparation of more electropositive metals, such as post-transition metals and semi-metals. The potential of this method is also clearly displayed for the preparation of alloys, intermetallics and core-shell nanostructures with a very large diversity of compositions and architectures.

Dense arrays of cobalt nanorods as rare-earth free permanent magnets

We demonstrate in this paper the feasibility to elaborate rare-earth free permanent magnets based on cobalt nanorods assemblies with energy product (BH)max exceeding 150 kJ m(-3). The cobalt rods were prepared by the polyol process and assembled from wet suspensions under a magnetic field. Magnetization loops of dense assemblies with remanence to a saturation of 0.99 and squareness of 0.96 were measured. The almost perfect M(H) loop squareness together with electron microscopy and small angle neutron scattering demonstrate the excellent alignment of the rods within the assemblies. The magnetic volume fraction was carefully measured by coupling magnetic and thermogravimetric analysis and found in the range from 45 to 55%, depending on the rod diameter and the alignment procedure. This allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m(-3) was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets.

A transparent flexible z-axis sensitive multi-touch panel based on colloidal ITO nanocrystals

Bottom-up fabrication of a flexible multi-touch panel prototype based on transparent colloidal indium tin oxide (ITO) nanocrystal (NC) films is presented. A series of 7% Sn(4+) doped ITO NCs protected by oleate, octanoate and butanoate ligands are synthesized and characterized by a battery of techniques including, high resolution transmission electron microscopy, X-ray diffraction, (1)H, (13)C and (119)Sn nuclear magnetic resonance spectroscopy, and the related diffusion ordered spectroscopy. Electrical resistivities of transparent films of these NCs assembled on flexible polyethylene terephthalate substrates by convective self-assembly from their suspension in toluene decrease with the ligand length, from 220 × 10(3) for oleate ITO to 13 × 10(3)Ω cm for butanoate ITO NC films. A highly transparent, flexible touch panel based on a matrix of strain gauges derived from the least resistive film of 17 nm butanoate ITO NCs sensitively detects the lateral position (x, y) of the touch as well as its intensity over the z-axis. Being compatible with a stylus or bare/gloved finger, a larger version of this module may be readily implemented in upcoming flexible screens, enabling navigation capabilities over all three axes, a feature highly desired by the display industry.

Multiple large surface photodynamic therapy sessions with topical methylaminolaevulinate in PTCH heterozygous mice

BACKGROUND

Photodynamic therapy (PDT) combines the administration of a photosensitizer with its subsequent activation by light of the appropriate wavelength. Methylaminolaevulinate (MAL) is a photosensitizer precursor, transformed by cells into protoporphyrin IX. The PTCH gene plays a central role in the genesis of basal cell carcinoma (BCC). The PTCH transgenic mouse develops microscopic BCCs when chronically exposed to ultraviolet (UV) or ionizing radiation.

OBJECTIVES

The aim of this study was to explore the ability of multiple large surface MAL-PDT to prevent BCC, using the PTCH heterozygous mouse as a model.

METHODS

Thirty-five mice were exposed to UV radiation for a total of 20 weeks. Group 1 (20 mice) was exposed only to UV whereas group 2 (15 mice) was exposed to UV and weekly to MAL-PDT. At 28 weeks the mice were killed and the skin of the back processed for standard histopathology. Assessment was blind and any slide showing the presence of BCC was counted as a single BCC. The number of mice in groups 1 and 2 showing BCC were compared using Fisher's exact test.

RESULTS

Nineteen BCCs in nine mice from group 1 were found, but no BCCs in mice from group 2. The difference was statistically significant (P = 0.001).

CONCLUSIONS

Weekly suberythematous PDT sessions with topical MAL were able to delay the development of microscopic BCCs in PTCH mice chronically exposed to UV radiation.

Irradiance and light dose influence histological localization of photodamage induced by photodynamic therapy with aminolaevulinic acid

BACKGROUND

Photodynamic therapy (PDT) with aminolaevulinic acid (ALA) is used in many countries for the treatment of actinic keratoses.

OBJECTIVES

The objectives of the current study were to evaluate the influence of irradiance and light dose on the localization and extent of photodamage to mouse skin following ALA-PDT.

METHODS

In this study we evaluated the influence of irradiance and light dose on epidermal photodamage following ALA-PDT. Groups of hairless mice received an intraperitoneal injection of ALA followed 2 h later by exposure to 12 J cm(-2), 24 J cm(-2) or 48 J cm(-2) of unfiltered light from a slide projector. For each of these fluences, groups of mice were exposed at the following irradiances: 5 mW cm(-2), 20 mW cm(-2) or 40 mW cm(-2). Skin biopsies were performed 24 h and 72 h later.

RESULTS

Histological localization of photodamage was influenced by irradiance and light dose. At high irradiance and low fluence, PDT photodamaged cells were mostly located in the upper area of the epidermis whereas at lower irradiance and high fluence the complete epidermis was necrotic and often absent 24 h after light exposure. Protoporphyrin IX (PpIX) fluorescence intensity was similar in the upper and lower region of the epidermis 2 h after ALA injection. The decrease in PpIX fluorescence intensity immediately after light exposure was also similar in both regions of the epidermis.

CONCLUSIONS

The localization of photodamage following ALA-PDT is influenced by irradiance and light dose. This phenomenon cannot be explained by differences in PpIX intensity in the epidermis either before or after light exposure.

Systemic photodynamic therapy with aminolaevulinic acid delays the appearance of ultraviolet-induced skin tumours in mice

BACKGROUND

Photodynamic therapy (PDT) with topical aminolaevulinic acid (ALA) has recently been approved by the US Food and Drug Administration for the treatment of actinic keratoses.

OBJECTIVES

To determine whether weekly systemic suberythemogenic ALA-PDT could prevent the appearance of ultraviolet (UV) -induced skin tumours in hairless mice.

METHODS

One group of 20 mice received daily UV radiation from FS 20 tubes, and weekly intraperitoneal injections of ALA 40 mg kg(-1), each followed 3 h later by 12 J cm(-2) of white light (ALA-PDT). Control groups consisted of mice exposed only to UV, to UV and ALA without white light, or UV and white light without ALA, as well as untreated mice.

RESULTS

The tumour-free survival was significantly longer for mice exposed to daily UV and weekly ALA-PDT as compared with the control groups. Neither the mortality nor the incidence of large skin tumours was higher in the UV/ALA-PDT group than in mice exposed only to UV. In vivo fluorescence spectroscopy showed that the 635-nm fluorescence emission within tumours was lower than in normal skin 3 h after ALA administration. This was also confirmed by quantitative fluorescence microscopy.

CONCLUSIONS

Systemic ALA-PDT can delay the appearance of UV-induced skin tumours in mice without increasing mortality or the incidence of large tumours.

DEVELOPMENT OF NONINVASIVE AND QUANTITATIVE METHODOLOGIES FOR THE ASSESSMENT OF CHRONIC ULCERS AND SCARS IN HUMANS

Chronic ulcers are a significant and common cause of morbidity and mortality worldwide. They disrupt the epidermis and dermis, resulting in a loss of barrier function. Keloids and hypertrophic scars (benign cutaneous tumors) represent an abnormal healing response. These fibroproliferative disorders are characterized by an overabundance of collagen and accumulation of extracellular matrix due to an imbalance between synthesis and degradation, culminating in excessive scarring. The objectives of this study were to evaluate and compare noninvasive biophysical methods for the measurement of outstanding quantitative parameters of scars and chronic ulcers, and to establish correlations between the parameters measured and the results of conventional subjective clinical evaluations. The development of new technologies, based on ultrasonography and laser Doppler, makes possible new dermatological evaluation methods. Fifteen patients (6 females and 9 males) with 15 chronic ulcers (4 diabetic ulcers, 10 venous ulcers and 1 pressure ulcer) and 30 patients (19 females and 11 males) with 30 scars (25 hypertrophic and 5 keloids) were included in this study. Clinical evaluation was performed by a dermatologist, an aesthetic surgeon and an endocrinologist. Biophysical measurements were used to assess local blood flow by laser Doppler flowmetry (Moor DRT4), thickness and echogenicity by high frequency ultrasonography (20 MHz, Dermascan C) and ulcer linear dimensions by image analysis. Our results show that blood flow within the ulcers and scars was higher than within normal skin. Also, skin thickness of chronic ulcers was decreased when compared to normal skin; the thickness of hypertrophic scars, but not of keloids, was increased in comparison to normal skin, and presented the possibility of measuring wound and scar surfaces with precision. In summary, this pilot study established the feasibility of measuring various biophysical parameters and adapted their potential utility to research on wounds.

Photodynamic therapy with 5-aminolevulinic acid induces apoptosis and caspase activation in malignant T cells

BACKGROUND

Preliminary studies have suggested that photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) can improve psoriasis and mycosis fungoides, two diseases where normal or malignant T cells play a central role.

OBJECTIVES

To determine if ALA-PDT induces apoptosis and caspase activation in Jurkat cells, a malignant T-cell line.

METHODS

Jurkat cells were incubated with ALA in the presence of [14C]-thymidine followed by red light exposure. DNA fragmentation was measured 24 hours later with a DNA elution assay. The influence on DNA fragmentation of ALA concentration, time between ALA addition and light exposure, as well as light fluence were studied. The occurrence of oligonucleosome-sized DNA fragmentation was also studied with DNA electrophoresis. Caspase-3-like activity was monitored by measuring Ac-DEVD-AMC hydrolysis.

RESULTS

DNA fragmentation as high as 88% was observed 24 hours after ALA-PDT. The percentage of DNA fragmentation increased with increasing doses of ALA, red light fluence, as well as longer incubation time with ALA. DNA fragmentation was observed as early as 3 hours after ALA-PDT. The presence of apoptosis after ALA-PDT was confirmed by DNA electrophoresis. An increase in caspase-3-like activities was detected following ALA-PDT.

CONCLUSION

ALA-PDT induces apoptosis and caspase-3-like activation in Jurkat cells.

In vitro selective modulation of cellular glutathione by a humanized native milk protein isolate in normal cells and rat mammary carcinoma model

We report the in vitro selective inhibitory activity of a humanized whey protein concentrate IMMUNOCAL on growth of mammary carcinoma cells and Jurkat T cells in comparison to normal peripheral blood mononuclear cells. We relate this inhibitory activity to a selective depletion of intracellular glutathione synthesis. The use of humanized whey protein concentrate as a food supplementation may have direct implication in clinical trial with adjuvant chemotherapy.

Evidence for an apical, nonregulated protein secretion in pig exocrine pancreas

Secretory proteins are segregated into two pathways out of the trans-Golgi network of regulated secretory cells. To identify proteins specifically secreted by pathways other than the one leading to zymogen granule exocytosis in the exocrine pancreas, conscious permanently cannulated pigs were perfused with atropine to inhibit the regulated fusion of granules. Atropine almost totally inhibited the protein secretion after 1 h of perfusion. The secretion of GP-2, a glycosyl phosphatidylinositol-anchored protein of the zymogen granule membrane, was partially inhibited but was never totally abolished by atropine perfusion. The pattern of proteins secreted under atropine was almost totally different. Soluble GP-2 was the major secretory product. Its specific activity increased 60 times over its normal level in all other conditions. This secretion clearly originated from nonregulated pathways. Results suggest that during the atropine block the apical plasmalemma could be the source of the released GP-2 and that the sustained nature of this release is compatible with a replenishment of the plasmalemma with GP-2 by the continuous exocytosis of vesicles from the nonregulated pathways.

Reconstitution in vitro of the pH-dependent aggregation of pancreatic zymogens en route to the secretory granule: implication of GP-2

Regulated secretory proteins are thought to be sorted in the trans-Golgi network (TGN) via selective aggregation. To elucidate the biogenesis of the secretory granule in the exocrine pancreas, we reconstituted in vitro the conditions of pH and ions believed to exist in the TGN using the end product of this sorting process, the zymogen granule contents. Protein aggregation was dependent on pH (acidic) and on the presence of cations (10 mM Ca2+, 150 mM K+) to reproduce the pattern of proteins found in the granule. The constitutive secretory protein IgG was excluded from these aggregates. Zymogen aggregation correlated with the relative proportion of the major granule membrane protein GP-2 in the assay. These results show that the glycosylphosphatidylinositol-anchored protein GP-2 co-aggregates with zymogens in the acidic environment believed to exist in the pancreatic TGN, and thus suggest that GP-2 would function as a membrane anchor for zymogen aggregates, facilitating their entrapment in budding vesicles directed towards the regulated secretory pathway.

Fetal sex determination by ultrasound scan in the second and third trimesters

Sector real-time ultrasound examinations of the fetal perineal area were done on fetuses ranging in age from 14 weeks to term. An attempt was made to determine fetal sex in 404 consecutive cases. Seventeen cases were lost to follow-up and 20 fetuses under 16 weeks of age were omitted, as only two predictions were made in this group. The fetal sex was predicted in 266 of the remaining 367 fetuses with 93% accuracy. In this series, 194 fetuses were less than 24 weeks of age; within this group, 118 predictions were made with an accuracy rate of 86%.