Nanoparticles - Info

Nanoparticles

Table of contents

• Particle sizes
• Particle shapes
• Particle coatings
• Particle production
• Particle metrics
• Quantum dots
• Magnetic nanoparticles
• Microspheres / Microparticles
• Upconverting nanoparticles
• Conjugated nanoparticles

Particle sizes

Based on their diameter, particles can be divided into different groups:

Their size is also the explanation for an interesting property: Since visible light ranges from a wavelength of 400 - 700 nm, nanoparticles are invisible via optical microscops.

The use of electron microscops or microscops with laser enables scientist to make nanoparticles visible.

Since the typical diameter of an atom is 0.15 - 0.6 nm, due to their size, nanoparticles are right between bulk materials and atomic or molecular structures.

The production of nanoparticles is a branch of nanotechnology.

Particle shapes

The shape of nanoparticles can be described as either non-spherical (prisms, cubes, rods etc.) or spherical.

Especially in the case of non-spherical nanoparticles, their shape and size leads to specific chemical and physical properties that can be utilized in many ways.

Prominent materials for non-spherical nanoparticles are gold (Au), sivler (Ag) and platinum (Pt), while silica is often used for spherical nanoparticles.

Nanopartz is the only company worldwide to offer Spherical Gold Nanoparticles from 1nm to 1500nm in diameter, Gold Nanorods with Surface Plasmon Resonances from 550nm to 2100nm, and Gold Nanowires up to 40 microns in length.

The particle's color,cause by their resonance wavelength, can be shifted by fine tuning the geometrical properties of the particles. This way they can be used e.g. molecular labeling and biomolecular assays.

In contrast to nanoparticles, colloids are a mixture of particles: They consist of particles of one phase that are disperesed or suspended within an other phase.

Particle coatings

Nanoparticle can be coated with other substances. This layer, although only one molecular thick, can drastically alter the particle's properties. Among the effected properties are the particle's chemical reactivity, catalytic activity and stability in suspension.

Particle production

Nanoparticles can be produced in many ways. One, biological, way is to breakdown polymers (cellulose, lignin, chitin or starch) into their individual nanoscale building blocks.

Particle metrics

• Size & dispersion
• Shape
• Chemical composition & crystal structure
• Surface area
• Surface chemistry & charge
• Solubility

Quantum dots

Quantum dots are semiconductor nanocrystals. Quantum mechanics lead to their optical and electronic properties differing from those of larger particles.

When exposed to UV light quantum dots emit light.

Magnetic nanoparticles

Magnetic nanoparticles are micro- or nanomaterial with magnetic properties.

Magnetic nanoparticles can be composed of different materials such as iron oxide, nickel and cobalt.

Microspheres / Microparticles

Microparticles are small spherical particles. Their diameter ranges from 1 - 1000 µm.

Microparticles are made from glass, polymers, metal or ceramic and can be either solid or hollow shells.

The usage of polymers (polyethylene and polystyrene) is especially common in cell sorting and immunoprecipiation: Proteins and ligands adsorb onto polystyrene.

Upconverting nanoparticles

Upconverting nanoparticles, short "UCNPs", are particles in the nanoscale. Their diameter ranges from 1 - 100 nm.

They pocess photon upconverting properties. The process of photon upconversion starts with two or more lower energy photons. When excited via a laser in the infrared spectrum they are converted into one photon with high energy, that is emitted in the visible or ultraviolet spectrum.

Upconverting nanoparticles can be used in in vivo imaging, bio-sensing and nanomedicine.

Among their benefits are cellular uptake that is highly efficient, their optical penetrating power is very high while they cause very little background noise in deep tissue levels.

A further benefit is that their deeply penetrating light causes lesser damager to the cells and requires lower energy levels.

Conjugated nanoparticles

Nanoprobes offers a wide range of conjugated gold nanoparticles: