Ziwen Jiang

Functional Gold Nanoparticles as Potent Antimicrobial Agents against Multi-Drug-Resistant Bacteria

We present the use of functionalized gold nanoparticles (AuNPs) to combat multi-drug-resistant pathogenic bacteria. Tuning of the functional groups on the nanoparticle surface provided gold nanoparticles that were effective against both Gram-negative and Gram-positive uropathogens, including multi-drug-resistant pathogens. These AuNPs exhibited low toxicity to mammalian cells, and bacterial resistance was not observed after 20 generations. A strong structure–activity relationship was observed as a function of AuNP functionality, providing guidance to activity prediction and rational design of effective antimicrobial nanoparticles.

Gold Nanoparticles for Nucleic Acid Delivery

Gold nanoparticles provide an attractive and applicable scaffold for delivery of nucleic acids. In this review, we focus on the use of covalent and noncovalent gold nanoparticle conjugates for applications in gene delivery and RNA-interference technologies. We also discuss challenges in nucleic acid delivery, including endosomal entrapment/escape and active delivery/presentation of nucleic acids in the cell.

Detection of Escherichia coli in Drinking Water Using T7 Bacteriophage-Conjugated Magnetic Probe

In this study, we demonstrate a bacteriophage (phage)-based magnetic separation scheme for the rapid detection of Escherichia coli (E. coli) in drinking water. T7 phage is a lytic phage with a broad host range specificity for E. coli. Our scheme was as follows: (1) T7 bacteriophage-conjugated magnetic beads were used to capture and separate E. coli BL21 from drinking water; (2) subsequent phage-mediated lysis was used to release endemic β-galactosidase (β-gal) from the bound bacterial cells; (3) the release of β-gal was detected using chlorophenol red-β-d-galactopyranoside (CRPG), a colorimetric substrate which changes from yellow to red in the presence of β-gal. Using this strategy, we were able to detect E. coli at a concentration of 1 × 10(4) CFU·mL(-1) within 2.5 h. The specificity of the proposed magnetic probes toward E. coli was demonstrated against a background of competing bacteria. By incorporating a pre-enrichment step in Luria-Bertani (LB) broth supplemented with isopropyl β-d-thiogalactopyranoside (IPTG), we were able to detect 10 CFU·mL(-1) in drinking water after 6 h of pre-enrichment. The colorimetric change can be determined either by visual observation or with a reader, allowing for a simple, rapid quantification of E. coli in resource-limited settings.

Direct Cytosolic Delivery of siRNA Using Nanoparticle‐Stabilized Nanocapsules

The use of nanoparticle-stabilized nanocapsules (NPSCs) for the direct cytosolic delivery of siRNA is reported. In this approach, siRNA is complexed with cationic arginine-functionalized gold nanoparticles by electrostatic interactions, with the resulting ensemble self-assembled onto the surface of fatty acid nanodroplets to form a NPSC/siRNA nanocomplex. The complex rapidly delivers siRNA into the cytosol through membrane fusion, a mechanism supported by cellular uptake studies. Using destabilized green fluorescent protein (deGFP) as a target, 90% knockdown was observed in HEK293 cells. Moreover, the delivery of siRNA targeting polo-like kinase 1 (siPLK1) efficiently silenced PLK1 expression in cancer cells with concomitant cytotoxicity.

Quantitative Tracking of Protein Trafficking to the Nucleus Using Cytosolic Protein Delivery by Nanoparticle-Stabilized Nanocapsules

We describe a method for quantitative monitoring of subcellular protein trafficking using nanoparticle-stabilized nanocapsules for protein delivery. This method provides rapid delivery of the protein into the cytosol, eliminating complications from protein homeostasis processes found with cellularly expressed proteins. After delivery, nuclear protein trafficking was followed by real time microscopic imaging. Quantitative analyses of the accumulation percentage and the import dynamics of the nuclear protein trafficking, demonstrate the utility of this method for studying intracellular trafficking systems.

Fully Zwitterionic Nanoparticle Antimicrobial Agents through Tuning of Core Size and Ligand Structure

Zwitterionic nanoparticles are generally considered nontoxic and noninteracting. Here, we report effective and selective antimicrobial activity of zwitterionic gold nanoparticles (AuNP) through modulation NP size and surface charge orientation. Using a set of 2, 4, and 6 nm core AuNPs, increasing particle size increased antimicrobial efficiency through bacterial membrane disruption. Further improvement was observed through control of the ligand structure, generating antimicrobial particles with low hemolytic activity and demonstrating the importance of size and surface structure in dictating the bioactivity properties of nanomaterials.

Rapid Coating of Surfaces with Functionalized Nanoparticles for Regulation of Cell Behavior

A robust monolayer of nanoparticles is formed via dip-coating of cell culture plates. These surfaces provide cell type-specific modulation of growth behavior without the uptake of nanoparticles.

Multi-Stimuli-Responsive Amphiphilic Assemblies through Simple Postpolymerization Modifications

A strategy to construct different stimuli responsive polymers from post polymerization modifications of a single polymer scaffold via thiol-disulfide exchange has been developed. Here, we report on a random copolymer that enables the design and syntheses of a series of dual or multi-stimuli responsive nanoassemblies using a simple post-polymerization modification step. The reactive functional group involves a side chain monopyridyl disulfide unit, which rapidly and quantitatively reacts with various thiols under mild conditions. Independent and concurrent incorporation of physical, chemical or biologically responsive properties have been demonstrated. We envision that this strategy may open up opportunities to simplify the synthesis of multi-functional polymers with broad implications in a variety of biological applications.

Cytosolic delivery of large proteins using nanoparticle-stabilized nanocapsules

We report an effective intracellular delivery strategy for proteins of high molecular weight using AuNP stabilized capsules. This strategy provides direct delivery to the cytosol, avoiding endosomal entrapment.

Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions

Rational design of organic 2D (O2D) materials has made some progress, but it is still in its infancy. A class of self-assembling small molecules is presented that form nano/microscale supramolecular 2D materials in aqueous media. A judicial combination of four different intermolecular interactions forms the basis for the robust formation of these ultrathin assemblies. These assemblies can be programmed to disassemble in response to a specific protein and release its non-covalently bound guest molecules.