DNA-coated gold nanoparticles for sensing and drug delivery

In recent years inorganic nanoparticles have been of great scientific interest not only due to the fact that they can be tailored in morphology allowing for the tuning of their optical and electronic properties but also due to their rich surface chemistry. Recent advances in conjugation techniques have allowed for the surface functionalization of nanoparticles with ligands such as synthetic oligonucleotides. This has led to the development of bio-nanomaterials that have been successfully used in applications ranging from bio sensing to the targeted delivery of molecules such as drugs.This thesis focuses on the design and synthesis of advanced DNA-coated gold nanostructures that can perform the synergistic tasks of sensing and drug delivery in cells.Gold nanoparticles functionalized with synthetic oligonucleotides were assembled into dimers using copper free click chemistry and were used for the intracellular detection of up to two mRNA targets. Once taken up by cells they showed great biocompatibility, no significant susceptibility to degradation by nucleases and most importantly excellent specificity towards the mRNA sequence they were designed to detect.Furthermore, DNA-coated gold nanoparticle dimers were developed into multifunctional nanostructures. In addition to live cell mRNA detection we showed how they could also be designed to deliver up to two chemotherapeutic drugs. By relying on the specificity of the gold nanoparticle dimer towards an mRNA target, cell specific drug delivery was made possible thus demonstrating the synergistic capabilities of this system.Finally with a view of shedding light on the interaction between DNA-coated gold nanoparticles and cells their intracellular fate including the time point and location of mRNA detection after cellular entry was investigated.<br/

Investigating the stability of DNA-coated gold nanoparticles

In this paper we investigate how the density of oligonucleotides around spherical 15 nm gold nanoparticles (AuNPs) influences their stability against degradation by DNase I. We show that a significant decrease in the number of oligonucleotides attached to the AuNP surface is directly correlated with an increase in the DNA degradation by DNase I. Our experimental observations suggest that a close packing of oligonucleotides into a 3d arrangement at the surface of AuNPs endows the probes with the necessary stability required for their use in intracellular applications

A Method for the Growth of Uniform Silica Shells on Different Size and Morphology Upconversion Nanoparticles

Lanthanide-doped upconversion nanoparticles have emerged as attractive candidates for biomedical applications. This is due to their excitation and emission wavelengths, which lay the foundation for deeper penetration depth into biological tissue, higher resolution due to reduced scattering and improved imaging contrast as a result of a decrease in autofluorescence background. Usually, their encapsulation within a biocompatible silica shell is a requirement for their dispersion within complex media or for further functionalization of the upconversion nanoparticle surface. However, the creation of a silica shell around upconversion nanoparticles can be often challenging, many times resulting in partial silica coating or nanoparticle aggregation, as well as the production of a large number of silica particles as a side product. In this work we demonstrate a method to accurately predict the experimental conditions required to form a high yield of silica-coated upconversion nanoparticles, regardless of their shape and size

A method for the growth of uniform silica shells on different size and morphology upconversion nanoparticles

Lanthanide-doped upconversion nanoparticles have emerged as attractive candidates for biomedical applications. This is due to their excitation and emission wavelengths, which lay the foundation for deeper penetration depth into biological tissue, higher resolution due to reduced scattering and improved imaging contrast as a result of a decrease in autofluorescence background. Usually, their encapsulation within a biocompatible silica shell is a requirement for their dispersion within complex media or for further functionalization of the upconversion nanoparticle surface. However, the creation of a silica shell around upconversion nanoparticles can be often challenging, many times resulting in partial silica coating or nanoparticle aggregation, as well as the production of a large number of silica particles as a side product. In this work we demonstrate a method to accurately predict the experimental conditions required to form a high yield of silica-coated upconversion nanoparticles, regardless of their shape and size

Anion exchange in inorganic perovskite nanocrystal polymer composites

We demonstrate a facile, low-cost and room-temperature method of anion exchange in cesium lead bromide nanocrystals (CsPbBr3 NCs), embedded into a polymer matrix. The anion exchange occurs upon exposure of the solid CsPbBr3 NCs/PDMS nanocomposite in controlled anion precursor gas atmosphere. The rate and extent of the anion exchange reaction can be controlled via the variation of either the exposure time or the relative concentration of the anion precursor gas. Post-synthesis chemical transformation of perovskite nanocrystal-polymer composites is not readily achievable using conventional methods of anion exchange, which renders the gas-assisted strategy extremely useful. We envisage that this work will enable the development of solid-state perovskite NCs optoelectronic devices

DNA: Gold nanoparticles designed for mRNA sensing in cells: imaging of the gold nanoparticles using two photon photoluminescence spectroscopy

Recently DNA-coated gold nanoparticles have emerged as ideal tools for the detection of mRNA in cells using dye modified oligonucleotides. However, the tracking of the gold core has been hindered by the small size of the particle core. In this work we utilize a home built set up and 43 nm DNA-coated spherical gold nanoparticles for the simultaneous imaging of mRNA detection using fluorescence microscopy and the gold nanoparticle core using two photon photoluminescence (TPPL).</p

Functionalized nanoparticles and applications

In this paper we present chemical methods developed in our laboratory to synthesize nanoparticles for biomedical and imaging applications. We show that branched gold nanoparticles can be used for imaging applications whereas goldnanorods can be successfully coated with materials such as silica making them ideal for further bio-functionalization

Raw data for A Method for the Growth of Uniform Silica Shells on Different Size and Morphology Upconversion Nanoparticles

To support article &quot;A Method for the Growth of Uniform Silica Shells on Different Size and Morphology Upconversion Nanoparticles&quot; in Nanoscale Advances</span