Abstract
It has recently been shown that surface plasmon microscopy (SPM) allows single nanoparticles (NPs) on sensor surfaces to be detected and analyzed. The authors have applied this technique to study the adsorption of single metallic and plastic NPs. Binding of gold NPs (40, 60 and 100 nm in size) and of 100 nm polystyrene NPs to gold surfaces modified by differently ω-functionalized alkyl thiols was studied first. Self-assembled monolayers (SAM) with varying terminal functions including amino, carboxy, oligo(ethylene glycol), methyl, or trimethylammonium groups were deposited on gold films to form surfaces possessing different charge and hydrophobicity. The affinity of NPs to these surfaces depends strongly on the type of coating. SAMs terminated with trimethylammonium groups and carboxy group display highly different affinity and therefore were preferred when creating patterned charged surfaces. Citrate-stabilized gold NPs and sulfate-terminated polystyrene NPs were used as negatively charged NPs, while branched polyethylenimine-coated silver NPs were used as positively charged NPs. It is shown that the charged patterned areas on the gold films are capable of selectively adsorbing oppositely charged NPs that can be detected and analyzed with an ~1 ng⋅mL−1 detection limit. Graphical abstractSelf-assembled monolayers of ω-functionalized alkyl thiols were deposited on a gold layer of a patterned sensor array. The charge-selective binding of single nanoparticles to such surfaces was registered by wide-field surface plasmon microscopy. Electronic supplementary materialThe online version of this article (doi:10.1007/s00604-016-1956-7) contains supplementary material, which is available to authorized users.
Highlights
Detection, quantification, and characterization of nanoparticles of biological origin or engineered nanomaterials is the actual challenge of different fields of analytical science, including food and environmental safety, bioanalytics, and medical diagnostics [1,2,3,4]
Several methods to detect single nanoparticles (NPs) were reported [5]. One of such techniques is based on surface plasmon resonance (SPR) which belongs to the highly sensitive refractometric transducers [6] and has become a routine technique for investigation of interactions of biomolecules [7, 8]. This approach has been realized as an imaging system (SPR imaging or SPM – surface plasmon microscopy) [9]
A high sensitivity of this approach is based on the referencing: a few μm vicinity around these NPs in course of their adsorption is compared with the rest of the sensor surface
Summary
Quantification, and characterization of nanoparticles of biological origin or engineered nanomaterials is the actual challenge of different fields of analytical science, including food and environmental safety, bioanalytics, and medical diagnostics [1,2,3,4]. Several methods to detect single nanoparticles (NPs) were reported [5] One of such techniques is based on surface plasmon resonance (SPR) which belongs to the highly sensitive refractometric transducers [6] and has become a routine technique for investigation of interactions of biomolecules [7, 8]. It was applied for detection of viruses [24] and for tracking of mitochondria in the living cells [25] Another approach, contrarily to the high-NA approach, is based on the conventional SPM [9] where the incident light is coupled to a plasmonic sensor layer by a glass prism (Fig. 1). The surfaces patterned by oppositely charged ω-functionalized alkyl thiols can be used as sensors to determine the sign of the surface charge of nanoparticles
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
