Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

Abstract

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 ...

Laser-Induced Deposition of Plasmonic Ag and Pt Nanoparticles, and Periodic Arrays

“…It is characterized by good correlation of the chemical composition of the precursor and the deposited structures that is a consequence of the mild conditions of laser irradiation. The main competitive advantage of LID over other laser-based methods is its ability to synthesize NPs directly on any given/preselected surface area of the substrate [21,22]. It allows 'on-site' functionalization of various types of surfaces with NPs active in catalysis and electrocatalysis, surface-enhanced Raman spectroscopy (SERS), plasmon-enhanced fluorescence, energy conversion, solar cell technologies, etc.…”

Investigating the Optical Properties of a Laser Induced 3D Self‐Assembled Carbon–Metal Hybrid Structure

“…The linear birefringence remains nearly constant (Δ n = 0.09 ± 0.005) over a spectral range of 400–700 nm, which is generally comparable to naturally birefringent materials, but it outperforms other orthorhombic crystalline structures . Furthermore, the combination of the field enhancement introduced by the plasmonic Au–Ag nanoparticle inclusions and the birefringence suggest a strong potential for opto‐electronics, nanophotonic, nonlinear optical experiments, and applications …”

“…The combination of carbonaceous materials with metal nanoparticles can give rise to a unique set of properties, which may not be observed in individual elements. Fabrication of such structures, has been an active research field with applications ranging from surface enhanced Raman scattering (SERS) to electrochemical processes, enhanced plasmonics response, and optical sensing . In recent years, laser induced deposition has been reported as a means for the controllable fabrication of such hybrids .…”

Hybrid Orthorhombic Carbon Flakes Intercalated with Bimetallic Au-Ag Nanoclusters: Influence of Synthesis Parameters on Optical Properties

“…The laser-induced deposition of the hybrid carbon-metal structures is a straight-forward and easy-to-implement procedure that does not require intense laser irradiation or special equipment. This process results in the formation of NPs [ 23 , 24 , 25 ] or other structures such as flakes and flowers [ 26 ] of controllable composition, depending on the chosen SMC and the solvent. An interesting type of structures resulting from this laser-induced process are carbon flakes, which are the first reported orthorhombic form of carbon with embedded Au-Ag nanoclusters.…”