Integration of optical and electrochemical sensors on a microfluidic platform using organic optoelectronic components and silver nanowires.

Since the emergence of microfluidic platforms sensors integration has been a major challenge. With the advances in miniaturization of these platforms, there is a need for solutions to integrate various optical components in order to build sensors, which will offer different detection characteristics such as several emission and sensing wavelengths. Moreover, the integration of an electrochemical sensor including a transparent electrode that will be compatible with the optical sensor represents an additional challenge. In this perspective, organic optoelectronic devices combined with silver nanowire electrodes could be a solution. The integration of a fluorescent sensor and an electrochemical oxygen sensor into a microfluidic platform and the different characteristics, advantages and disadvantages that offer organic light-emitting diodes (OLED), organic photodetectors (OPD) and silver nanowire electrodes are discussed. Finally, an example of the integration of an optical and an electrochemical sensor into a microfluidic chip for water pollution detection will be described.

Biocompatibility and functionality of a tissue-engineered living corneal stroma transplanted in the feline eye.

PURPOSE: Corneal tissue shortage has become a major concern worldwide, which has motivated the search for alternative solutions to eye bank human eyes for corneal transplantation. Minimally invasive lamellar transplantation and tissue engineering may offer new opportunities for the rehabilitation of diseased corneas. The aim of this study was to evaluate the biocompatibility and functionality of stromal lamellar grafts tissue-engineered (TE) in vitro and transplanted in vivo in the cornea of a feline model. METHODS: The corneal stromas were engineered in culture from corneal stromal cells using the self-assembly approach, without the addition of exogenous material or scaffold. Eight healthy animals underwent two intrastromal grafts in one eye and the contralateral eye was used as a control. Animals were followed with slit-lamp ophthalmic examination, corneal esthesiometry and optical coherent tomography. Confocal microscopy, immunofluorescence, histology, and transmission electron microscopy (TEM) were performed at 4 months. RESULTS: Four months after transplantation, the TE-stromal grafts were transparent, functional, and well tolerated by the eye. All grafts remained avascular, with no signs of immune rejection, despite a short course of low-dose topical steroids. Corneal sensitivity returned to preoperative level and reinnervation of the grafts was confirmed by confocal microscopy and immunofluorescence. Histology and TEM of the TE-grafts showed a lamellar stromal structure with regular collagen fibril arrangement. CONCLUSIONS: These results open the way to an entirely new therapeutic modality. Intracorneal filling using a biocompatible, transparent, and malleable TE-stroma could be the basis for multiple types of novel therapeutic options in corneal interventional surgery.

A short-term in vivo experimental model for Fuchs endothelial corneal dystrophy.

PURPOSE: We evaluated the in vivo functionality of a corneal endothelium tissue-engineered using corneal endothelial cells from human patients with Fuchs endothelial corneal dystrophy (FECD). METHODS: A total of 15 healthy cats underwent full-thickness corneal transplantation. All transplants were of xenogeneic human origin and all grafts but two were tissue-engineered. In seven animals the graft corneal endothelium was tissue-engineered using cultured corneal endothelial cells from humans with FECD (TE-FECD). Two control animals were grafted with an endothelium engineered using cultured endothelial cells from normal eye bank corneas (TE-normal). Two controls received a native full-thickness corneal transplant, and four other controls were grafted with the stromal carrier only (without endothelial cells). Outcome parameters included graft transparency (0, opaque to 4, clear), pachymetry, optical coherence tomography, endothelial cell morphometry, transmission electron microscopy (TEM), and immunostaining of function-related proteins. RESULTS: Seven days after transplantation, 6 of 7 TE-FECD grafts, all TE-normal grafts, and all normal native grafts were clear (transparency score >3), while all carriers-only grafts were opaque (score <1). The mean pachymetry was 772 ± 102 µm for TE-FECD, 524 ± 11 µm for TE-normal, 555 ± 48 for normal native, and 1188 ± 223 µm for carriers only. TEM showed subendothelial loose fibrillar material deposition in all TE-FECD grafts. The TE endothelium expressed Na(+)-K(+)/ATPase and Na(+)/HCO3(-). CONCLUSIONS: Restoration of transparency and corneal thickness demonstrated that the TE-FECD grafts were functional in vivo. This novel FECD seven-day living model suggests a potential role for tissue engineering leading to FECD cell rehabilitation.

Use of chlorophyll a fluorescence to detect the effect of microcystins on photosynthesis and photosystem II energy fluxes of green algae.

The phenomenon of cyanobacteria bloom occurs widely in lakes, reservoirs, ponds and slow flowing rivers. Those blooms can have important repercussions, at once on recreational and commercial activities but also on the health of animals and human beings. Indeed, many species are known to produce toxins which are released in water mainly at cellular death. The cyanotoxin most frequently encountered is the microcystin (MC), a hepatotoxin which counts more than 70 variants. The use of fast tests for the detection of this toxin is thus a necessity for the protection of the ecosystems and the human health. A promising method for their detection is a bioassay based on the chlorophyll a fluorescence of algae. Many studies have shown that algae are sensible to diverse pollutants, but were almost never used for cyanotoxins. Therefore, our goals were to evaluate the effect of microcystin on the fluorescence of different species of algae and how it can affect the flow of energy through photosystem II. To reach these objectives, we exposed four green algae (Scenedesmus obliquus CPCC5, Chlamydomonas reinhardtii CC125, Pseudokirchneriella subcapitata CPCC37 and Chlorella vulgaris CPCC111) to microcystin standards (variants MC-LF, LR, RR, YR) and to microcystin extracted from Microcystis aeruginosa (CPCC299), which is known to produce mainly MC-LR. Chlorophyll a fluorescence was measured by PEA (Plant Efficiency Analyzer) and LuminoTox. The results of our experiment showed that microcystins affect the photosynthetic efficiency and the flow of energy through photosystem II from 0.01 µg/mL, within only 15 min. From exposure to standard of microcystin, we showed that MC-LF was the most potent variant, followed by MC-YR, LR and RR. Moreover, green algae used in this study demonstrated different sensitivity to MCs, S. obliquus being the more sensitive. We finally demonstrated that LuminoTox was more sensitive to MCs than parameters measured with PEA, although the latter brings indication on the mode of action of MCs at the photosynthetic apparatus level. This is the first report showing a photosynthetic response within 15 min of exposure. Our results suggest that bioassay based on chlorophyll fluorescence can be used as a rapid and sensitive tool to detect microcystin.

Culture of human corneal endothelial cells isolated from corneas with Fuchs endothelial corneal dystrophy.

The purpose of this study was to assess the feasibility of initiating primary cultures of corneal endothelial cells from patients suffering from Fuchs endothelial corneal dystrophy (FECD; MIM# 1036800). We also evaluated which conditions yielded the best results for culture. Twenty-nine patients undergoing Descemet stripping automated endothelial keratoplasty consented to the use of their excised Descemet's membrane for this study. Out of the 29 specimens, 18 successfully initiated a culture. Cell morphology varied between endothelial (rounded, slightly elongated cells, n = 12) and fibroblastic-like (thin and very elongated cells, n = 6). These differences in cell morphology were also observed with the normal human corneal endothelial cell cultures. The cultures that initially presented an endothelial morphology maintained their shape in subcultures. Clusterin expression was similar in FECD and normal endothelial cells. Transmission electron microscopy of FECD Descemet's membranes showed a high degree of various abnormalities generally found in this disease, such as a thickened Descemet's membrane, presence of a posterior banded layer, presence of a fibrillar layer and striated bodies of various sizes and periodicities. Patient's age was predictive of culture success, all younger FECD donors generating cultures of endothelial morphology. The absence of a fibrillar layer was also a factor associated with greater success. Culture success was not dependent on specimen size, specimen pigmentation, or patient's preoperative central corneal thickness. In conclusion, this paper shows for the first time that central Descemet's membranes of patients suffering from FECD possess proliferative endothelial cells that can be isolated and cultured without viral transduction, opening the way for new in vitro studies of this disease.

Effect of endocrine disrupters on photosystem II energy fluxes of green algae and cyanobacteria.

Among the numerous toxics found in the aquatic environment, endocrine disrupters can interfere with the normal functioning of the endocrine system of several organisms, leading to important consequences. Even if algae and cyanobacteria are non-target organisms without endocrine system, our goals were to verify if endocrine disrupters can affect photosynthetic activity and how energy flows through photosystem II (PSII) were altered. To reach these objectives, we exposed, for 15 min, two green algae (Chlamydomonas reinhardtii strain CC125, Pseudokirchneriella subcapitata strain CPCC37) and a toxic and a non-toxic strain of Microcystis aeruginosa (CPCC299 and CPCC632 respectively) to 4-octylphenol, 4-nonylphenol and ß-estradiol at concentrations ranging from 0.1 to 5 µg/mL. We have shown for the first time that endocrine disrupters may have drastic effects on PSII energy fluxes. Furthermore, we showed that various species have different sensitivity to endocrine disrupters. P. subcapitata was tolerant to each endocrine disrupter tested, while flows of energy through PSII were affected similarly, but at different extent, for the other species. Cyanobacterial PSII energy fluxes were more affected than green algae, suggesting that the prokaryotic characteristics of these organisms are responsible of their high sensitivity.

Indirect genetic effects and the evolution of aggression in a vertebrate system.

Aggressive behaviours are necessarily expressed in a social context, such that individuals may be influenced by the phenotypes, and potentially the genotypes, of their social partners. Consequently, it has been hypothesized that indirect genetic effects (IGEs) arising from the social environment will provide a major source of heritable variation on which selection can act. However, there has been little empirical scrutiny of this to date. Here we test this hypothesis in an experimental population of deer mice (Peromyscus maniculatus). Using quantitative genetic models of five aggression traits, we find repeatable and heritable differences in agonistic behaviours of focal individuals when presented with an opponent mouse. For three of the traits, there is also support for the presence of IGEs, and estimated correlations between direct and indirect genetic (rAO,F) effects were high. As a consequence, any selection for aggression in the focal individuals should cause evolution of the social environment as a correlated response. In two traits, strong positive rAO,F will cause the rapid evolution of aggression, while in a third case changes in the phenotypic mean will be constrained by negative covariance between direct and IGEs. Our results illustrate how classical analyses may miss important components of heritable variation, and show that a full understanding of evolutionary dynamics requires explicit consideration of the genetic component of the social environment.