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This study shows a viable and straightforward microfluidic method of assembly of cardanol (CA) and cholesterol (CH) into amphiphile nanostructures obtained through a hydrodynamic focusing approach according to which an alcoholic solution of CA and CH is constrained within a two-dimensional lamina shape by two lateral streams of borate buffer solution. The process is performed within glass-made cross-shaped micro-sized fluidic chips specially designed to achieve a laminar regime. CA, distilled from the cashew nut shell liquid, is demonstrated as a surface-active molecule in borate buffer basic medium and when mixed with CH it produces versatile nanovesicles through an in-batch solvent-free process. Compared to this conventional method, the microfluidic route allows operating under continuous flows, with a reduced amount of reagents and at lower experimental temperatures, ensuring no waste formation and the achievement of size-monodisperse amphiphile nanostructures that do not need further steps of purification. Electron microscopy analyses demonstrate that upon increasing CH in the lipid mixture, a switchover from spherical CA micelles to CA/CH mixed closed vesicles occurs. Differential scanning microcalorimetry confirms the formation of vesicular structures and evidences the primary role of CH, which increasingly lowers the temperature of transition depending on its concentration.

Glass micromachining is a basic technology to achieve microfluidic networks for lab-on-a-chip applications. Among several methods to microstructure glass, the simplest and most widely applied is wet chemical etching (WE). However, accurate control of the reaction conditions to perform reproducible, fast and safe glass etching is not straightforward. Herein, microwave-assisted WE is demonstrated to intensify the glass etching action under safe working and finely monitored operative conditions and to produce smooth deep channels in short processing times with reduced underetching effects.

An extensive investigation of the photodegradation of the photochromic molecule 1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indole] in a polymer matrix is studied under irradiation with ultraviolet (UV) laser pulses of 248 and 308 nm wavelength. Apart from the effect of the wavelength, the effect of the pulse duration is also presented using pulses of 30 ns and 500 fs for the 248 nm wavelength. To tackle the problem of oxidative degradation upon irradiation of the photochromic molecules which is known to play a principal role in the photodegradation process, we incorporate Iron(II) phthalocyanine molecules in the examined matrices. These molecules upon UV irradiation are dissociated into photoproducts that can interact efficiently with electron acceptor groups in the polymer, partly responsible for the photochromic degradation. The phthalocyanine molecules seem to protect efficiently the photochromic molecules only at low laser fluences. Moreover, in the case of ultrashort pulses the degradation of the photochromic molecules is found to be more intense that in the case of ns pulses, indicating multiphoton absorption mechanisms, unless low laser fluences are used. (c) 2006 Elsevier B.V. All rights reserved.

Carbon dioxide (CO2)-laser processing of glasses is a versatile maskless writing technique to engrave micro-structures with flexible control on shape and size. In this study, we present the fabrication of hundreds of microns quartz micro-channels and micro-holes by pulsed CO2-laser ablation with a focus on the great potential of the technique in microfluidics and biomedical applications. After discussing the impact of the laser processing parameters on the design process, we illustrate specific applications. First, we demonstrate the use of a serpentine microfluidic reactor prepared by combining CO2-laser ablation and post-ablation wet etching to remove surface features stemming from laser-texturing that are undesirable for channel sealing. Then, cyclic olefin copolymer micro-pillars are fabricated using laser-processed micro-holes as molds with high detail replication. The hundreds of microns conical and square pyramidal shaped pillars are used as templates to drive 3D cell assembly. Human Umbilical Vein Endothelial Cells are found to assemble in a compact and wrapping way around the micro-pillars forming a tight junction network. These applications are interesting for both Lab-on-a-Chip and Organ-on-a-Chip devices.

Lab-On-a-Brane (LOB) represents a class of Lab-On-a-Chip (LOC) integrating flexible, highly gas permeable and biocompatible thin membranes (TMs). Here we demonstrate the potentiality of LOBs as cell biochips promoting 3D cell growth. The human cancer cells MCF-7 were cultured into standard multiwells (MWs) and into polydimethylsiloxane (PDMS) MWs, LOCs, and LOBs of different wettability. Surface treatments based on oxygen plasma and coating deposition have been performed to produce hydrophilic, hydrophobic, and oleophobic chips. By a comparison between all these chips, we observed that 3D cell aggregation is favored in LOBs, independent of substrate wettability. This maybe attributed to the TM flexibility and the high oxygen/carbon dioxide permeability. Ultimately, LOBs seem to combine the advantages of LOCs as multi-well microfluidic chips to reduce operation time for cell seeding and medium refresh, with the mechanical/morphological properties of PDMS TMs. This is convenient in the perspective of applying mechanical stimuli and monitoring cell stiffness, or studying the metabolism of molecules permeable to PDMS membrane in response to external stimuli with interesting outcomes in cellular biology.

We present an experimental method for measuring “realistically” the swelling ratio in terms of weight (SR W ) of PDMS, where “realistically” means without the underestimation involved by the standard protocol (weight-measurements in open environment with time-delay incompatible with fast solvent evaporation rate). Comparison with the literature demonstrates that misleading conclusions can result under application of the standard protocol to very volatile solvents. To discuss this point, we develop a mathematical expression of SR W including solvent properties and the effective amount of sorbed solvent determining a weight gain, consider two solvents with different volatility that severely swell PDMS (i.e., toluene and dichloromethane), check that the results of our measurements are consistent with theoretical predictions, demonstrate that our protocol rules out any dependence of SR W on the solvent volatility and its reliability to measure and compare SR W values of PDMS (or any swelling polymer/soft material) in the case of solvents with very different volatility.

The production of reproducible batches of liposomes suitable for parenteral administration is a time-consuming, multi-step process requiring extensive workable area. Microfluidic Hydrodynamic Focusing (MHF) chips allow one-pot synthesis of injectable size liposomes, although the use of low height-to-width aspect ratio (AR) microreactors limits the production rates. Herein, aiming at scaling up liposome production, while avoiding lithographic methods and clean room facilities, easy-fabrication glass MHF large channel (MHF-LC) chips of AR = 1, 3 with T-shaped and coaxial injection geometries are demonstrated. Narrowly distributed unilamellar nanoliposomes (unprecedented minimum average diameters 85 nm and polydispersity index of 0.13) with the formulation of a known pharmaceutical product (i.e., DOXIL®(CAELYX®)) are synthesized at production rates 15–20 times larger than T-MHF chips. The dependence of liposome size on the Reynolds numbers (in the range of 5–50) in the coaxial configuration is discussed as due to viscosity-induced mixing dynamics at the water–ethanol interface.

Protein biomarkers are important diagnostic tools for cancer and several other diseases. To be validated in a clinical context, a biomarker should satisfy some requirements including the ability to provide reliable information on a pathological state by measuring its expression levels. In parallel, the development of an approach capable of detecting biomarkers with high sensitivity and specificity would be ideally suited for clinical applications. Here, we performed an immune-based label free assay using Surface Plasmon Resonance (SPR)-based detection of the soluble form of E-cadherin, a cell-cell contact protein that is involved in the maintaining of tissue integrity. With this approach, we obtained a specific and quantitative detection of E-cadherin from a few hundred microliters of serum of breast cancer patients by obtaining a 10-fold enhancement in the detection limit over a traditional colorimetric ELISA.

In this paper, an unprecedented inspection of the effects of thermal aging on swelling and wettability of PDMS as a function of the interplay between temperature (from 100 to 180 °C) and duration (from 20 min to 24 h) of the treatment is presented. Dichloromethane was used as sample swelling solvent and the swollen weight was measured by a method properly designed to avoid underestimation related to the volatility of the solvent. This study: i) provides practical guidelines for performing optimal thermal aging treatments of PDMS against swelling (for example, in microfluidic platforms to synthesize cancer tracers), and ii) contributes to the fundamental understanding of the swelling process of soft matter systems. An interpretative model has been developed of the observed swelling regimes based on heating-promoted crosslinking and chain reorganization (inter-chain mobility) at short-lasting heating timescales and conformational changes (intra-chains transitions) at long-lasting heating timescales.