The self-assembled structures of atomically precise, ligand-protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding-directed self-assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p-mercaptobenzoic acid (pMBA)-protected atomically precise silver nanocluster, Na [Ag (pMBA) ], and pMBA-functionalized GNRs were used. High-resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H-bonding, leading to octahedral symmetry. The use of water-dispersible gold nanoclusters, Au (pMBA) and Au (pMBA) , also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities.

Here, we have exploited the heightened extracellular concentration of matrix metalloproteinase-9 (MMP-9) to induce surface-conversional properties of nanogels with the aim of tumor-specific enhanced cellular uptake. A modular polymeric nanogel platform was designed and synthesized for facile formulation and validation of MMP-9-mediated dePEGylation and generation of polyamine-type surface characteristics through peptide N-termini. Nanogels containing MMP-9-cleavable motifs and different poly(ethylene glycol) corona lengths (350 and 750 g/mol) were prepared, and enzymatic surface conversional properties were validated by MALDI characterization of cleaved byproducts, fluorescamine assay amine quantification, and zeta potential. The nanogel with a shorter PEG length, mPEG350-NG, exhibited superior surface conversion in response to extracellular concentrations of MMP-9 compared to that of the longer PEG length, mPEG750-NG. Confocal microscopy images of HeLa cells incubated with both fluorescein-labeled nanogels and DiI-encapsulated nanogels demonstrated greater uptake following MMP-9 "activation" for mPEG350-NG compared to its nontreated "passive" mPEG350-NG parent, demonstrating the versatility of such systems to achieve stimuli-responsive uptake in response to cancer-relevant proteases.

The development of nanoparticle‐based biomedical applications has been hampered due to undesired off‐target effects. Herein, we outline a cellular AND gate to enhance uptake selectivity, in which a nanoassembly–cell interaction is turned on, only in the concurrent presence of two different protein functions, an enzymatic reaction (alkaline phosphatase, ALP) and a ligand–protein (carbonic anhydrase IX, CA IX) binding event. Selective uptake of nanoassemblies was observed in cells that overexpress both of these proteins (unicellular AND gate). Interestingly, selective uptake can also be achieved in CA IX overexpressed cells, when cocultured with ALP overexpressed cells, where the nanoassembly presumably acts as a mediator for cell–cell communication (bicellular AND gate). This logic‐gated cellular uptake could find use in applications such as tumor imaging or theranostics.

Responsive surfactants designed with kinetic control to triggers are rare and offer new opportunities in generating tunable reactive assemblies. In this work, we discuss the design of novel molecular assemblies based on covalently triggerable surfactants programmed to respond exclusively to nucleophilic triggers to cause interfacial alterations. Through a formal SN2' type Michael addition chemistry, these induced alterations at the interface of single and dynamic double emulsions can be kinetically tuned and brought about by various small molecule nucleophiles and functionalized nanoassemblies to cause macroscopic responses -bursting or morphology changes. In addition, separate responsive modalities can be used to further control the emulsion systems to impart cascade trigger behavior and programmed release applications.