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Be my guest: A supramolecular host-guest interaction is utilized for highly efficient bioorthogonal labeling of cellular targets. Antibodies labeled with a cyclodextrin host molecule bind to adamantane-labeled magnetofluorescent nanoparticles (see picture) and provide an amplifiable strategy for biomarker detection that can be adapted to different diagnostic techniques such as molecular profiling or magnetic cell sorting., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nanoparticle based platforms for identification of chemical and biological agents offer substantial benefits to biomedical and environmental science. These platforms benefit from the availability of a wide variety of core materials as well as the unique physical and chemical properties of these nanoscale materials. This review surveys some of the emerging approaches in the field of nanoparticle based detection systems, highlighting the nanoparticle based screening methods for metal ions, proteins, nucleic acids, and biologically relevant small molecules., (Copyright 2009 Elsevier B.V. All rights reserved.)

Gold nanoparticles were coated with a short peptide to promote intracellular delivery of membrane-impermeable proteins. Through microscopy and enzyme assays, we demonstrated the particles were able to transport functional enzymes into a variety of cell lines. Significantly, the transported proteins were able to escape from endosomes. Moreover, these particles showed no apparent cytotoxicity.

Amino-acid-functionalized gold clusters modulate the catalytic behavior of alpha-chymotrypsin (ChT) toward cationic, neutral, and anionic substrates. Kinetic studies reveal that the substrate specificity (k(cat)/K(M)) of ChT-nanoparticle complexes increases by approximately 3-fold for the cationic substrate but decreases by 95% for the anionic substrate as compared with that of free ChT, providing enhanced substrate selectivity. Concurrently, the catalytic constants (k(cat)) of ChT show slight augmentation for the cationic substrate and significant attenuation for the anionic substrate in the presence of amino-acid-functionalized nanoparticles. The amino acid monolayer on the nanoparticle is proposed to control both the capture of substrate by the active site and release of product through electrostatic interactions, leading to the observed substrate specificities and catalytic constants.

The article offers information on various synthetic routes and properties of gold nanoparticles (AuNPs) which are applicable for various sensing strategies. It mentions that the citric acid which acts reducing and stabilizing agents also provides 20 nm diameter for AuNPs. It highlights the place exchange method in forming mixed monolayer AuNPs, adding that the technique introduces chemical functionality in AuNPs.

Supramolecular chemistry provides a versatile tool for the organization of molecular systems into functional structures and the actuation of these assemblies for applications through the reversible association between complementary components. Use of this methodology in living systems, however, represents a significant challenge owing to the chemical complexity of cellular environments and lack of selectivity of conventional supramolecular interactions. Herein, we present a host-guest system featuring diaminohexane-terminated gold nanoparticles (AuNP-NH2) and complementary cucurbit[7]uril (CB[7]). In this system, threading of CB[7] on the particle surface reduces the cytotoxicity of AuNP-NH2 through sequestration of the particle in endosomes. Intracellular triggering of the therapeutic effect of AuNP-NH2 was then achieved through the administration of 1-adamantylamine (ADA), removing CB[7] from the nanoparticle surface, causing the endosomal release and concomitant in situ cytotoxicity of AuNP-NH2. This supramolecular strategy for intracellular activation provides a new tool for potential therapeutic applications. [ABSTRACT FROM AUTHOR]

Amino-acid-functionalized gold clusters modulate the catalytic behavior of α-chymotrypsin (ChT) toward cationic, neutral, and anionic substrates. Kinetic studies reveal that the substrate specificity (kcat/ KM) of ChT-nanoparticle complexes increases by ∼3-fold for the cationic substrate but decreases by 95% for the anionic substrate as compared with that of free ChT, providing enhanced substrate selectivity. Concurrently, the catalytic constants (kcat) of ChT show slight augmentation for the cationic substrate and significant attenuation for the anionic substrate in the presence of amino-acid-functionalized nanoparticles. The amino acid monolayer on the nanoparticle is proposed to control both the capture of substrate by the active site and release of product through electrostatic interactions, leading to the observed substrate specificities and catalytic constants. [ABSTRACT FROM AUTHOR]

The article focuses on the importance of the gold nanoparticles (AuNPs) in the release of caged anticancer drug. The drug delivery system (DDS) is vital in the regulation of drug release and the improvement of therapeutic efficacy of conventional pharmaceuticals. The DDS helps in the drug release which is being supported by the AuNPs.

The article describes a self-assembly method to prepare stable colloidal shells and membranes by cross-linking nanoparticles at the liquid-liquid interface using coordination chemistry. According to the authors, terpyridine thiol functionalized FePt nanoparticles were used to prepare stable water-in-oil colloidal shells and membranes, with cross-linking effected at room-temperature through Fe(II) metal ion complexation.