Micro-chips based on organic-inorganic hybrid nanoparticles (NPs) composed of nanoalloys of gold (Au) and silver (Ag) embedded in an amorphous carbonaceous matrix (C-Au-Ag NPs) were prepared directly on a substrate by the laser-induced deposition (for short: LID) method. The C-Au-Ag NPs show a unique plasmon resonance which enhances Raman scattering of analytes, making the μ-chips suitable to detect ultra-low-volumes (10 −12 liter) and concentrations (10 −9 M) of bio-agents and a hazardous compound.These micro-chips constitute a novel, flexible solid-state device that can be used for applications in pointof-care diagnostics, consumer electronics, homeland security and environmental monitoring.Detection and identification of low concentrations in small volumes of hazardous and biological substances are currently important to address challenges in environmental monitoring, homeland security and medicine. Recently, different groups have developed devices based on metal nanoparticles (NPs) with the capacity to detect low concentrations of substances. 1 However, devices associated with NPs require two stage development: (i) synthesis of NPs and (ii) integration of the NPs into devices. Even though the synthesis of NPs is well established (especially for Au and Ag) and different integrating approaches of NPs into devices have been demonstrated (such as Layer-by-Layer and drop casting, optical and nano lithography, direct laser writing of optofluidic and multifunctional microfluidic chips, laser ablation of Si wafer surfaces, followed by coating with metal thin films such as gold etc.), 2 the state-of-the art sensors/devices still suffer from a lack of control over parameters. Moreover, chemical functionalities on the NP surfaces are not stable over time and react with H 2 O/O 2 in ambient conditions and impair the device performance. 1e Here, we propose a new method for the fabrication of micro-chip devices (for short μ-devices) based on nanoalloys of Au-Ag NPs that are simultaneously synthesized by direct laser writing and embedded in a carbonaceous matrix (hereinafter, C-Au-Ag NPs). It should be noted that the suggested process is photoinduced that allows avoiding side effects of thermal phenomena (delocalization of the deposition process, thermal decomposition, etc.). The C-Au-Ag NPs provide high stability and new functionalities of combined properties of the metals and the carbon that opens the door for new applications. 3 For example, a core of gold-silver nanoalloys coated with a carbon shell demonstrates excellent efficiency as a Raman tag for quantitative immunoassays and high catalytic activity. 3 However, the preparation of metal NPs or nanoalloys in a carbonaceous matrix is complicated, time consuming and requires the use of dangerous chemical compounds and chemical equipment. 4 In our case, we present a fast and coherent Laser-Induced liquid phase Deposition (LID) method for direct writing of μ-chips based on NPs from solutions on any desired substrate with controlled assembly of elements i.e. of active ...

We present an original type of model electrode system consisting of bimetallic Au-Ag nanoparticles embedded in an amorphous carbon matrix with an extremely well-defined geometry of parallel, straight, cylindrical macropores. The samples are prepared in one step by direct laser deposition of the metal/carbon composite onto the inner walls of a porous 'anodic' alumina matrix serving as a template. The coating is homogeneous from top to bottom of the pores, and the amount of material deposited can be tuned by the duration of the deposition procedure. As a test system, we demonstrate that a bimetallic Ag-Au@C system is catalytically active for the electrochemical oxidation of glucose in alkaline solution, the anodic reaction of a direct glucose fuel cell. Furthermore, the electrocatalytic current density increases with the amount of Ag-Au@C NPs deposited, up to a point at which the pores are clogged with it. This type of model system allows for the systematic study of geometric effects in fuel cell electrodes. It can be generalized to a number of different nanoparticle compositions, and thereby, to various electrocatalytic reactions.

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