Clickable poly-L-lysine for the formation of biorecognition surfaces
Biomolecules are immobilized onto surfaces employing the fast and stable adsorption of poly-l-lysine (PLL) polymers and the versatile copper-free click chemistry reactions. This method provides the combined advantages of versatile surface adsorption with density control using polyelectrolytes and of the covalent and orthogonal immobilization of biomolecules with higher reaction rates and improved yields of click chemistry. Using DNA attachment as a proof of concept, control over the DNA probe density and applicability in electrochemical detection are presented.
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…
Low-fouling, mixed-charge poly-L-lysine polymers with anionic oligopeptide side-chains
Biosensors and biomedical devices require antifouling surfaces to prevent the non-specific adhesion of proteins or cells, for example, when aiming to detect circulating cancer biomarkers in complex natural media (e.g., in blood plasma or serum). A mixed-charge polymer was prepared by the coupling of a cationic polyelectrolyte and an anionic oligopeptide through a modified "grafting-to" method. The poly-l-lysine (PLL) backbone was modified with different percentages (y%) of maleimide-NHS ester chains (PLL-mal(y%), from 13% to 26%), to produce cationic polymers with specific grafting densities, obtaining a mixed-charge polymer. The anionic oligopeptide structure (CEEEEE) included one cysteine…
Selective Recognition and Sensing of Succinate vs. Other Aliphatic Dicarboxylates by Thiourea-Functionalized Gold Nanoparticles
Gold nanoparticles functionalized with thiourea moieties have been used as selective colorimetric sensors for the naked-eye detection of succinate versus other aliphatic dicarboxylates, all of them as their TBA salts. The detection process is based on the interparticle aggregation triggered by coordination of the end-carboxylates to the thiourea moieties of two different nanoparticles. This nanoparticle aggregation results in a batochromic shift of the plasmon resonance band and a visual color change from red to blue.
Functionalized Gold Nanoparticles as an Approach to the Direct Colorimetric Detection of DCNP Nerve Agent Simulant
New functionalized gold nanoparticles have been synthesized and their ability to act as colorimetric molecular probes for the naked-eye detection of nerve agent simulant DCNP has been studied. The detection process is based on the com
A Simple System Based on a Thiourea-Modified Fluorescein for ω-Amino Acid Discrimination
A thiourea-modified fluorescein derivative was synthesized by reaction of fluorescein isothiocyanate with 2-(2-aminoethoxy)ethan-1-ol. UV/Vis absorption and fluorescence emission spectroscopy studies demonstrated that this heteroditopic receptor was able to discriminate among linear aliphatic ω-amino acids with different chain lengths.