A Simple, Yet Multifunctional, Nanoformulation for Eradicating Tumors and Preventing Recurrence with Safely Low Administration Dose

Designing simple-structured nanomedicine without lacking key functionalities, thereby avoiding incomplete damage or relapse of tumor with the administration of a safe dose, is pivotal for successful cancer nanotherapy. We herein presented a nanomedicine of photodynamic therapy (PDT) that simply assembled amphiphilic macromolecules of poly-l-lysine conjugating with photosensitizers onto hydrophobic upconverting nanoparticles. We demonstrated that the nanoformulation, despite its simple structure and synthesis, simultaneously possesses multiple features, including substantial payload of photosensitizers, avid cellular internalization both in vitro and in vivo, efficient diffusion and broad distribution in tumor lesion, and potent fatality for cancer stem cells that are refractory to other therapy modalities. Because of the combination of these functionalities, the tumors in mice were eradicated and no relapse was observed after at least 40 days, just with an extremely low intraperitoneal injection dose of 5.6 mg/kg. Our results suggested a strategy for designing multifunctional nanomedicines with simple construct and efficacious therapeutic response and presented the promising potential of PDT for a radical cure of cancer.

Control of Intra- versus Extracellular Bioorthogonal Catalysis Using Surface-Engineered Nanozymes

Bioorthogonal transformation of prodrugs and profluorophores using transition metal catalysts (TMCs) offers a promising strategy for therapeutic and imaging applications. Here, we report the surface engineering of nanoparticles to specifically localize gold nanoparticles (AuNPs) with encapsulated TMCs (nanozymes) to either the inside or outside of cells. The ability to control nanozyme localization and hence activity was demonstrated by the activation of pro-fluorophores and prodrugs intra- and extracellularly, establishing the potential of engineered nanozyme platforms for both diagnostic and therapeutic purposes.

Solubilization of Hydrophobic Catalysts Using Nanoparticle Hosts

A modular strategy for the solubilization and protection of hydrophobic transition metal catalysts using the hydrophobic pockets of water soluble gold nanoparticles is reported. Besides preserving original catalyst activity, this encapsulation strategy provides a protective environment for the hydrophobic catalyst and brings reusability. This system provides a versatile platform for the encapsulation of different hydrophobic transition metal catalysts, allowing a wide range of catalysis in water while uniting the advantages of homogeneous and heterogeneous catalysis in the same system.

Charge-Switchable Nanozymes for Bioorthogonal Imaging of Biofilm-Associated Infections

Early detection of biofilms is crucial for limiting infection-based damage. Imaging these biofilms is challenging: conventional imaging agents are unable to penetrate the dense matrix of the biofilm, and many imaging agents are susceptible to false positive/negative responses due to phenotypical mutations of the constituent microbes. We report the creation of pH-responsive nanoparticles with embedded transition metal catalysts (nanozymes) that effectively target the acidic microenvironment of biofilms. These pH-switchable nanozymes generate imaging agents through bioorthogonal activation of profluorophores inside biofilms. The specificity of these nanozymes for imaging biofilms in complex biosystems was demonstrated using coculture experiments.

Tuning DNA Condensation with Zwitterionic Polyamidoamine (zPAMAM) Dendrimers

Cationic dendrimers are promising vectors for non-viral gene due to their well-defined size and chemistry. We have synthesized a series of succinylated fourth generation (G4) PAMAM dendrimers to control the DNA packaging in dendriplexes, allowing us to probe the role of charge on DNA packaging. The self-assembly of DNA induced by these zwitterionic PAMAM (zPAMAM) was investigated using small-angle x-ray scattering (SAXS). We demonstrate that changing the degree of modification in zPAMAM-DNA significantly alters the packing density of the resulting dendriplexes. Salt sensitivities and pH dependence on the inter-DNA spacing were also examined. The swelling and stability to salt is reduced with increasing degree of PAMAM modification. Lowering the pH leads to significantly tighter hexagonal DNA packaging. In combination, these results show zPAMAM is an effective means to modulate nucleic acid packaging in a deterministic manner.

Nanoparticle probes for quantifying supramolecular determinants of biosurface affinity

Interactions between macromolecular systems and biosurfaces are complicated by both the complexity of these multivalent interactions and challenges in quantifying affinities. A library of gold nanoparticles (AuNPs) as multivalent probes is used to quantify biosurface affinity, using hair as a model targeted substrate.

Dual-Mode Mass Spectrometric Imaging for Determination of in Vivo Stability of Nanoparticle Monolayers

Effective correlation of the in vitro and in vivo stability of nanoparticle-based platforms is a key challenge in their translation into the clinic. Here, we describe a dual imaging method that site-specifically reports the stability of monolayer-functionalized nanoparticles in vivo. This approach uses laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging to monitor the distributions of the nanoparticle core material and laser desorption/ionization mass spectrometry (LDI-MS) imaging to report on the monolayers on the nanoparticles. Quantitative comparison of the images reveals nanoparticle stability at the organ and suborgan level. The stability of particles observed in the spleen was location-dependent and qualitatively similar to in vitro studies. In contrast, in vivo stability of the nanoparticles in the liver differed dramatically from in vitro studies, demonstrating the importance of in vivo assessment of nanoparticle stability.

Rapid and ultrasensitive detection of endocrine disrupting chemicals using a nanosensor-enabled cell-based platform

Endocrine disrupting chemicals (EDCs) interact with estrogen receptors (ERs), causing a broad range of adverse health effects. Current assays for EDC activity are slow and often lack sensitivity. We report here an ultra-sensitive nanosensor that can detect estrogenic cellular changes in ER(+) MCF-7 cells rapidly (minutes) at several orders of magnitude lower than the generally used assays. Notably, the sensor responses at these ultra-low EDC levels correlated with an increased synthesis phase (S-phase) cell population of EDC-treated cells. The nanosensor was also able to detect binary EDC mixture effects, with synergism observed for bisphenol A (BPA) - 17β-estradiol (E2), and antagonism for dicyclohexylphthalate (DCHP) - E2 and benzo(a)pyrene (BaP) - E2.

General Strategy for Direct Cytosolic Protein Delivery via Protein-Nanoparticle Co-engineering

Endosomal entrapment is a key hurdle for most intracellular protein-based therapeutic strategies. We report a general strategy for efficient delivery of proteins to the cytosol through co-engineering of proteins and nanoparticle vehicles. The proteins feature an oligo(glutamate) sequence (E-tag) that binds arginine-functionalized gold nanoparticles, generating hierarchical spherical nanoassemblies. These assemblies fuse with cell membranes, releasing the E-tagged protein directly into the cytosol. Five different proteins with diverse charges, sizes, and functions were effectively delivered into cells, demonstrating the generality of our method. Significantly, the engineered proteins retained activity after cytosolic delivery, as demonstrated through the delivery of active Cre recombinase, and granzyme A to kill cancer cells.

Sensing by Smell: Nanoparticle-Enzyme Sensors for Rapid and Sensitive Detection of Bacteria with Olfactory Output

We present here a highly efficient sensor for bacteria that provides an olfactory output, allowing detection without the use of instrumentation and with a modality that does not require visual identification. The sensor platform uses nanoparticles to reversibly complex and inhibits lipase. These complexes are disrupted in the presence of bacteria, restoring enzyme activity and generating scent from odorless pro-fragrance substrate molecules. This system provides rapid (15 min) sensing and very high sensitivity (10² cfu/mL) detection of bacteria using the human sense of smell as an output.

Cancer Cell Discrimination Using Host-Guest "Doubled" Arrays

We report a nanosensor that uses cell lysates to rapidly profile the tumorigenicity of cancer cells. This sensing platform uses host-guest interactions between cucurbit[7]uril and the cationic headgroup of a gold nanoparticle to non-covalently modify the binding of three fluorescent proteins of a multi-channel sensor in situ. This approach doubles the number of output channels to six, providing single-well identification of cell lysates with 100% accuracy. Significantly, this classification could be extended beyond the training set, determining the invasiveness of novel cell lines. The unique fingerprint of these cell lysates required minimal sample quantity (200 ng, ∼1000 cells), making the methodology compatible with microbiopsy technology.

Programmed Self-Assembly of Hierarchical Nanostructures through Protein-Nanoparticle Coengineering

Hierarchical organization of macromolecules through self-assembly is a prominent feature in biological systems. Synthetic fabrication of such structures provides materials with emergent functions. Here, we report the fabrication of self-assembled superstructures through coengineering of recombinant proteins and nanoparticles. These structures feature a highly sophisticated level of multilayered hierarchical organization of the components: individual proteins and nanoparticles coassemble to form discrete assemblies that collapse to form granules, which then further self-organize to generate superstructures with sizes of hundreds of nanometers. The components within these superstructures are dynamic and spatially reorganize in response to environmental influences. The precise control over the molecular organization of building blocks imparted by this protein-nanoparticle coengineering strategy provides a method for creating hierarchical hybrid materials.

Direct Cytosolic Delivery of CRISPR/Cas9-Ribonucleoprotein for Efficient Gene Editing

Genome editing through the delivery of CRISPR/Cas9-ribonucleoprotein (Cas9-RNP) reduces unwanted gene targeting and avoids integrational mutagenesis that can occur through gene delivery strategies. Direct and efficient delivery of Cas9-RNP into the cytosol followed by translocation to the nucleus remains a challenge. Here, we report a remarkably highly efficient (∼90%) direct cytoplasmic/nuclear delivery of Cas9 protein complexed with a guide RNA (sgRNA) through the coengineering of Cas9 protein and carrier nanoparticles. This construct provides effective (∼30%) gene editing efficiency and opens up opportunities in studying genome dynamics.

Enhanced Laser Desorption/Ionization Mass Spectrometric Detection of Biomolecules Using Gold Nanoparticles, Matrix, and the Coffee Ring Effect

Nanomaterials have been extensively used as alternate matrices to minimize the low molecular weight interferences observed in typical MALDI but such nanomaterials typically do not improve the spot-to-spot variability that is commonly seen. In this work, we demonstrate that nanoparticles and low matrix concentrations (<2.5 mg/mL) can be used to homogeneously concentrate analytes into a narrow ring by taking advantage of the "coffee ring" effect. Concentration of the samples in this way leads to enhanced signals when compared to conventional MALDI, with higher m/z analytes being enhanced to the greatest extent. Moreover, the ionization suppression often observed in samples with high salt concentrations can be overcome by preparing samples in this way. The ring that is formed is readily visible, allowing the laser to be focused only on spots that contain analyte. The coffee-ring effect represents a new mode by which nanomaterials can be used to enhance the MALDI-based detection of biomolecules.

Simultaneous cytosolic delivery of a chemotherapeutic and siRNA using nanoparticle-stabilized nanocapsules

We report on nanoparticle-stabilized capsules (NPSCs) as a platform for the co-delivery of survivin-targeted siRNA and tamoxifen. These capsules feature an inner oil core that provides a carrier for tamoxifen, and is coated on the surface with positively charged nanoparticles self-assembled with siRNA. The multifaceted chemical nature of the NPSC system enables the simultaneous delivery of both payloads directly into the cytosol in vitro. The NPSC co-delivery of tamoxifen and survivin-targeted siRNA into breast cancer cells disables the pathways that inhibit apoptosis, resulting in enhanced breast cell death.

Chemically Engineered Nanoparticle-Protein Interface for Real-Time Cellular Oxidative Stress Monitoring

A co-engineered nanoparticle/protein peroxide detector is created. This system features a gold nanoparticle functionalized with a galactose headgroup (AuNP-Gal) that reacts covalently with a boronate-modified green fluorescent protein (PB-GFP). Boronate acid-saccharide complexation between PB-GFP and AuNP-Gal affords a highly stable assembly. This complex is disrupted by peroxide, allowing quantitative and selective monitoring of hydrogen peroxide production in real time.

Light-triggered RNA release and induction of hMSC osteogenesis via photodegradable, dual-crosslinked hydrogels

AIM

To engineer a photodegradable hydrogel system for actively controlled release of bioactive unmodified RNA at designated time points to induce hMSC osteogenesis.

MATERIALS & METHODS

RNA/polyethylenimine complexes were loaded into dual-crosslinked photodegradable hydrogels to examine the capacity of UV light application to trigger their release. The ability of released RNA to drive hMSC osteogenic differentiation was also investigated.

RESULTS & CONCLUSION

RNA release from photodegradable hydrogels was accelerated upon UV application, which was not observed in non-photodegradable hydrogels. Regardless of the presence of UV light, released siGFP exhibited high bioactivity by silencing GFP expression in HeLa cells. Importantly, siNoggin or miRNA-20a released from the hydrogels induced hMSC osteogenesis. This system provides a potentially valuable physician/patient-controlled 'on-demand' RNA delivery platform for biomedical applications.

High Yield Synthesis of Aspect Ratio Controlled Graphenic Materials from Anthracite Coal in Supercritical Fluids

This paper rationalizes the green and scalable synthesis of graphenic materials of different aspect ratios using anthracite coal as a single source material under different supercritical environments. Single layer, monodisperse graphene oxide quantum dots (GQDs) are obtained at high yield (55 wt %) from anthracite coal in supercritical water. The obtained GQDs are ∼3 nm in lateral size and display a high fluorescence quantum yield of 28%. They show high cell viability and are readily used for imaging cancer cells. In an analogous experiment, high aspect ratio graphenic materials with ribbon-like morphology (GRs) are synthesized from the same source material in supercritical ethanol at a yield of 6.4 wt %. A thin film of GRs with 68% transparency shows a surface resistance of 9.3 kΩ/sq. This is apparently the demonstration of anthracite coal as a source for electrically conductive graphenic materials.

Surface Charge Controls the Suborgan Biodistributions of Gold Nanoparticles

Surface chemistry plays a deciding role in nanoparticle biodistribution, yet very little is known about how surface chemistry influences the suborgan distributions of nanomaterials. Here, using quantitative imaging based on laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we demonstrate that surface charge dictates the suborgan distributions of nanoparticles in the kidney, liver, and spleen of mice intravenously injected with functionalized gold nanoparticles. Images of the kidney show that positively charged nanoparticles accumulate extensively in the glomeruli, the initial stage in filtering for the nephron, suggesting that these nanoparticles may be filtered by the kidney at a different rate than the neutral or negatively charged nanoparticles. We find that positively and negatively charged nanoparticles accumulate extensively in the red pulp of the spleen. In contrast, uncharged nanoparticles accumulate in the white pulp and marginal zone of the spleen to a greater extent than the positively or negatively charged nanoparticles. Moreover, these uncharged nanoparticles are also more likely to be found associated with Kupffer cells in the liver. Positively charged nanoparticles accumulate extensively in liver hepatocytes, whereas negatively charged nanoparticles show a broader distribution in the liver. Together these observations suggest that neutral nanoparticles having 2 nm cores may interact with the immune system to a greater extent than charged nanoparticles, highlighting the value of determining the suborgan distributions of nanomaterials for delivery and imaging applications.

Quantitative imaging of 2 nm monolayer-protected gold nanoparticle distributions in tissues using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS)

Functionalized gold nanoparticles (AuNPs) have unique properties that make them important biomedical materials. Optimal use of these materials, though, requires an understanding of their fate in vivo. Here we describe the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to image the biodistributions of AuNPs in tissues from mice intravenously injected with AuNPs. We demonstrate for the first time that the distributions of very small (∼2 nm core) monolayer-protected AuNPs can be imaged in animal tissues at concentrations in the low parts-per-billion range. Moreover, the LA-ICP-MS images reveal that the monolayer coatings on the injected AuNPs influence their distributions, suggesting that the AuNPs remain intact in vivo and their surface chemistry influences how they interact with different organs. We also demonstrate that quantitative images of the AuNPs can be generated when the appropriate tissue homogenates are chosen for matrix matching. Overall, these results demonstrate the utility of LA-ICP-MS for tracking the fate of biomedically-relevant AuNPs in vivo, facilitating the design of improved AuNP-based therapeutics.

Photocleavable Hydrogels for Light-Triggered siRNA Release

A photocleavable hydrogel system for on-demand delivery of genetic material is reported. The release of short interfering RNAs can be triggered by the application of UV light without any loss in bioactivity. This approach provides a promising external stimulus-based nucleic acid delivery platform for applications in disease therapeutics and tissue regeneration.

Binding Studies of Cucurbit[7]uril with Gold Nanoparticles Bearing Different Surface Functionalities

Host-guest interactions between a synthetic receptor, cucurbit[7]uril (CB[7]), and gold nanoparticles (AuNPs) have been quantified using isothermal titration calorimetry. AuNPs were functionalized with ligands containing tertiary or quaternary benzylamine derivatives, with electron donating or withdrawing groups at the para position of the benzene ring. Analysis of binding interactions reveals that functional groups at the para position have no significant effect on binding constant. However, headgroups bearing a permanent positive charge increased the binding of AuNPs to CB[7] ten-fold compared to monomethyl counterparts.

Regulating exocytosis of nanoparticles via host-guest chemistry

Prolonged retention of internalized nanoparticulate systems inside cells improves their efficacy in imaging, drug delivery, and theranostic applications. Especially, regulating exocytosis of the nanoparticles is a key factor in the fabrication of effective nanocarriers for chemotherapeutic treatments but orthogonal control of exocytosis in the cellular environment is a major challenge. Herein, we present the first example of regulating exocytosis of gold nanoparticles (AuNPs), a model drug carrier, by using a simple host-guest supramolecular system. AuNPs featuring quaternary amine head groups were internalized into the cells through endocytosis. Subsequent in situ treatment of a complementary cucurbit[7]uril (CB[7]) to the amine head groups resulted in the AuNP-CB[7] complexation inside cells, rendering particle assembly. This complexation induced larger particle assemblies that remained sequestered in the endosomes, inhibiting exocytosis of the particles without any observed cytotoxicity.

A multichannel nanosensor for instantaneous readout of cancer drug mechanisms

Screening methods that use traditional genomic, transcriptional, proteomic and metabonomic signatures to characterize drug mechanisms are known. However, they are time consuming and require specialized equipment. Here, we present a high-throughput multichannel sensor platform that can profile the mechanisms of various chemotherapeutic drugs in minutes. The sensor consists of a gold nanoparticle complexed with three different fluorescent proteins that can sense drug-induced physicochemical changes on cell surfaces. In the presence of cells, fluorescent proteins are rapidly displaced from the gold nanoparticle surface and fluorescence is restored. Fluorescence 'turn on' of the fluorescent proteins depends on the drug-induced cell surface changes, generating patterns that identify specific mechanisms of cell death induced by drugs. The nanosensor is generalizable to different cell types and does not require processing steps before analysis, offering an effective way to expedite research in drug discovery, toxicology and cell-based sensing.

Environmentally responsive histidine-carboxylate zipper formation between proteins and nanoparticles

Interfacing synthetic materials with biomacromolecules provides new systems for biological applications. We report the creation of a reversible multivalent supramolecular "zipper" recognition motif between gold nanoparticles and proteins. In this assembly, carboxylate-functionalized nanoparticles interact strongly with oligohistidine tags. This interaction can be tuned through His-tag length, and offers unique binding profiles based on the pH and electrolyte concentration of the medium.

Tunable elastic modulus of nanoparticle monolayer films by host-guest chemistry

The elastic modulus of an ultrathin nanoparticle (NP) monolayer film is tuned by modulating the binding strength between the NPs on a molecular level. NP monolayer films constructed by crosslinking NPs of different binding affinities are fabricated at oil/water interfaces. By inducing buckling patterns on these films, the correlation between the binding affinity of the NPs and the elastic modulus is investigated.

The role of surface functionality in nanoparticle exocytosis

Getting out is just as important for nano-therapeutics as getting in. Exocytosis rates determine residency time in the cell, an important determinant for therapeutic efficacy and also for eventual clearance from the cell. In this study, it is shown that exocytosis efficiency is determined by surface functionality, providing a strategy for optimizing nanocarriers.

Mass spectrometric detection of nanoparticle host-guest interactions in cells

Synthetic host–guest chemistry is a versatile tool for biomedical applications. Characterization and detection of host–guest complexes in biological systems, however, is challenging due to the complexity of the biological milieu. Here, we describe and apply a mass spectrometric method to monitor the association and dissociation of nanoparticle (NP)-based host–guest interactions that integrates NP-assisted laser desorption/ionization (LDI) and matrix assisted laser desoption/ionization (MALDI) mass spectrometry. This LDI/MALDI approach reveals how NP surface functionality affects host–guest interactions in cells, information difficult to achieve using other techniques.

Probing the Protein-Nanoparticle Interface: The Role of Aromatic Substitution Pattern on Affinity

A new class of cationic gold nanoparticles has been synthesized bearing benzyl moieties featuring -NO₂ and -OMe groups to investigate the regioisomeric control of aromatic nanoparticle-protein recognition. In general, nanoparticles bearing electron withdrawing group demonstrated higher binding affinities towards green fluorescent protein (GFP) compared to electron-donating groups. Significantly, a ~7.5 and ~4.3 fold increase in binding with GFP was observed for -NO2 groups in meta- and para-position respectively, while ortho-substitution showed similar binding compared to the unsubstituted ring. These findings demonstrated that nanoparticle-protein interaction can be controlled by the tuning the spatial orientation and the relative electronic properties of the aromatic substituents. This improved biomolecular recognition provides opportunities for enhanced biosensing and functional protein delivery to the cells.

Inorganic Nanoparticles for Therapeutic Delivery: Trials, Tribulations and Promise

Inorganic nanomaterials have a wide array of physical and structural properties that make them attractive candidates for imaging and therapeutic delivery. Nanoparticle platforms have been intensely studied for these applications, and examples are starting to enter the clinic. This review looks at why inorganic particles provide promising platforms for biomedicine, and what issues need to be addressed for them to reach their potential.

25th anniversary article: interfacing nanoparticles and biology: new strategies for biomedicine

The exterior surface of nanoparticles (NPs) dictates the behavior of these systems with the outside world. Understanding the interactions of the NP surface functionality with biosystems enables the design and fabrication of effective platforms for therapeutics, diagnostics, and imaging agents. In this review, we highlight the role of chemistry in the engineering of nanomaterials, focusing on the fundamental role played by surface chemistry in controlling the interaction of NPs with proteins and cells.