Characterization of nanomaterials. .pptx

Characterization of nanomaterials

1. Instructor: Dr. Sadaf Hameed Characterization of Nanoparticles

2. outcomes (in this case the projected shadows) of an incompletely characterized object may cause misinterpretation. Why Characterization of Nanomaterial is Important?

3. 1 3 4 2 Parameters Size and Size Distribution Shape and Surface Charge Elemental and Chemical Composition Physio- chemical Analysis

4. 1 Size and Size Distribution Size refers to the spatial extent of an object. For a spherical object , size can be unambiguously described by one dimension. However, for non-spherical objects , several dimensions are needed to fully define the actual extension of an object. For a nanoparticle, size can refer to: i ) its overall physical dimension(s) defined by the atomic structure; ii) an effective size of the particle in a certain matrix according to its diffusion/sedimentation behavior, possibly including adsorption of matrix constituents to the nanoparticle surface, agglomeration or aggregation of the particles in the matrix;

5. 1 Size and Size Distribution

6. 2 Shape and Surface Charge Shape: O ften assumed spherical, nanoparticles feature a large variety of geometric and irregular shapes. Particles with equal composition and similar dimensions might present drastically different behaviors as a consequence of their shape, such as surface-binding capability, cellular uptake and release, optical and plasmonic effects. Surface Charge: The boundary between the solid and the fluid phase is a dynamic environment, and multiple phenomena, such as the presence of dangling bonds, or the adsorption or grafting of charged molecules contribute to the appearance of a net charge on the nanoparticle surface.

7. 2 Shape and Surface Charge This charge has a primary effect on the behavior of nanoparticles in different environments, in particular on controlling their tendency toward aggregation, as electrostatic repulsion between particles is a key factor promoting the stability of colloidal solutions

8. 3 Elemental and Chemical Composition The elemental and chemical composition of nanoparticle characterization refers to the process of analyzing and determining the types and quantities of elements and compounds present in nanoparticles. Elemental composition refers to the identification and quantification of the different elements present in the nanoparticles. It provides information about the types and relative amounts of elements such as gold, silver, iron, carbon, oxygen, etc., that make up the nanoparticles. Chemical composition involves the identification of specific chemical compounds or functional groups present in the nanoparticles.

9. 4 Physiochemical Characterization Mechanical properties, optical activity, surface area, and chemical reactions of nanoparticles are physiochemical characteristics obtainable from nanoparticles.

10. Characterization Techniques TEM SEM AFM XRD DLS UV-Vis FTIR EDX

11. SEM AFM XRD DLS UV-Vis FTIR EDX TEM Transmission Electron Microscopy (TEM) Transmission electron microscopy is undoubtedly one of the most important nanoparticle characterization techniques. TEM employs a focused electron beam on a thin (typically less than 200 nm) sample to produce micrographs of nanoscale materials with high lateral spatial resolution. TEM enables the investigation of size, shape, and crystal structure at the single-particle level . Once a representative group of images of the nanoparticle sample is acquired, the individual size of ≈1000 randomly selected nanoparticles should be measured to obtain meaningful statistics for size distribution determination.

12. This procedure can be done either manually (inherently affected by human errors, bias, and subjectivity) or using automated particle analysis methods. Limitations: Although TEM enables visual inspection of single particles with nanometer resolution, the whole workflow of sample preparation, measurement, and analysis can be extremely labor intensive.In addition, the nanoparticles have to be electron transparent and able to withstand the high vacuum and beam energy employed during characterization. Especially, due to the high-energy electron beam, sample damage is a known problem for organic, polymer and hybrid nanoparticles.

13. SEM AFM XRD DLS UV-Vis FTIR EDX TEM Main information derived: Nanoparticle size, size monodispersity , shape, aggregation state, detect and localize/quantify NPs in matrices, study growth kinetics.

14. AFM XRD DLS UV-Vis FTIR EDX TEM SEM Scanning Electron Microscopy (SEM) Scanning electron microscope enables imaging the sample surface by detecting secondary electrons emitted from the sample upon interaction with the impinging electron beam. In SEM, lower beam energies are utilized for sample imaging as compared to TEM characterization , which results in a limited penetration depth of the beam and, hence, in being sensitive solely to the specimen surface . However, this superficial interaction also implies that SEM characterization can be used for the analysis of the morphology of “thick” (>100 nm) samples, which is not possible with TEM

15. SEM typically requires conductive substrates for high-resolution imaging and nonconductive samples can be coated with a thin (5–10 nanometer) metallic film before being analyzed. This modification of size and surface structure of nonconductive nanoparticles due to sample preparation has to be accounted for when interpreting SEM micrographs. Finally, when comparing SEM and TEM images, it should be kept in mind that SEM only yields information on the sample surface structure, while TEM interacts with the whole sample volume, hence providing information on sample structure (e.g., it can provide information on the layer thicknesses of core/shell nanoparticles).

16. AFM XRD DLS UV-Vis FTIR EDX TEM SEM Main information derived: Morphology, dispersion of NPs in cells and other matrices/supports, precision in lateral dimensions of NPs, quick examination–elemental composition

17. XRD DLS UV-Vis 8 1 FTIR EDX TEM SEM AFM Atomic Force Microscopy (AFM) Atomic force microscopy is a scanning probe microscopy technique that can be used to probe and visualize the surface (and several other force-related quantities) of nanometer-sized or even atomic-sized objects. Working principle: A sharp tip at the end of a cantilever is rastered across the surface of a sample, and the forces the cantilever experiences during the measurement as a result of the interaction of the tip with the sample are recorded with the help of a laser beam reflected off the tip of the cantilever onto a photodiode array .

18. In general, three different modes are used: (1) contact mode, (2) noncontact mode and (3) tapping mode In contact mode , the tip is always in direct contact with the surface of the sample. In noncontact mode , a piezocrystal is used to drive oscillations of the cantilever at or close to its resonance frequency. These oscillations occur slightly above the surface of the sample, and the tip is never in direct contact with the sample surface. Tapping mode (or intermittent contact mode) is similar to noncontact mode. An oscillating cantilever is used as well, but instead of oscillating strictly above the sample surface, the tip “taps” on the surface during the oscillations. This mode is much less invasive than contact mode   

19. XRD DLS UV-Vis 8 1 FTIR EDX TEM SEM AFM Main information derived : NP size and shape in 3D mode, evaluate degree of covering of a surface with NP morphology, dispersion of NPs in cells and other matrices/supports, precision in lateral dimensions of NPs, quick examination–elemental composition

20. EDX TEM SEM UV-Vis FTIR AFM XRD DLS X-Ray Diffraction (XRD) X-ray Diffraction (XRD) is a widely used technique for analyzing the crystal structure and properties of materials. It is based on the principle of the diffraction of X-rays by the regular arrangement of atoms in a crystal lattice. Based on the intensity distribution of the scattered X-ray photons that are passing through the sample, information about particle size, size distribution, morphology, crystallinity, molecular weight, and agglomeration can be obtained.

21. EDX TEM SEM UV-Vis FTIR AFM XRD DLS Main information derived: Crystal structure, composition, crystalline grain size

22. SEM AFM XRD UV-Vis FTIR EDX TEM DLS Dynamic Light Scattering (DLS) Dynamic Light Scattering (DLS) is an important tool for characterizing nanoparticles and other colloidal solutions .  DLS measures light scattered from a laser that passes through a colloidal solution . By analyzing the modulation of the scattered light intensity as a function of time, information can be obtained on the size of the particle in solution. The analysis is based on the diffusive motion of particles in solution (Brownian motion) in which larger particles will move more slowly and scatter more light than smaller particles.

23. The hydrodynamic diameter (the diameter of a hypothetical nonporous sphere that diffuses at the same rate as the particles being characterized) can be calculated from the time dependence of the scattering intensity measurements. The hydrodynamic diameter is an important complement to other sizing measurements such as TEM because it provides information on the aggregation state of nanoparticle solutions. Stable unaggregated colloidal solutions will have particles with hydrodynamic diameters similar to or slightly larger than their TEM size while highly aggregated solution will have hydrodynamic diameters that are much larger than the TEM size.

24. SEM AFM XRD UV-Vis FTIR EDX TEM DLS Main information derived : Hydrodynamic size, detection of agglomerates. Zeta Potential Zeta potential (also known as the electrokinetic potential ) is a measure of the “effective” electric charge on the nanoparticle surface, and quantifies the charge stability of colloidal nanoparticles.  The magnitude of the Zeta Potential provides information about particle stability, with higher magnitude potentials exhibiting increased electrostatic repulsion and therefore increased stability. 0-5 mV : Particles tend to agglomerate or aggregate 5-20 mV : Particles are minimally stable 20-40 mV : Particles are moderately stable 40+ mV : Particles are highly stable

25. FTIR EDX TEM SEM AFM XRD DLS UV-Vis UV-Visible Spectroscopy UV-visible spectroscopy is a widely used technique for characterizing nanoparticles based on their absorption and scattering properties in the ultraviolet (UV) and visible regions of the electromagnetic spectrum. It provides valuable information about the electronic transitions and optical properties of nanoparticles. Here's how UV-visible spectroscopy is applied to nanoparticle analysis: Absorption spectra Quantification Size determination Shape analysis Aggregation State

26. SEM AFM XRD DLS EDX TEM UV-Vis FTIR Fourier Transform Infrared Spectroscopy (FTIR) Fourier Transform Infrared Spectroscopy (FTIR) is a powerful technique used for the analysis of nanoparticles. It provides information about the chemical composition, functional groups, and surface properties of nanoparticles.

27. TEM SEM AFM XRD DLS UV-Vis FTIR EDX Energy-Dispersive X-ray Spectroscopy (EDX) EDX (Energy-Dispersive X-ray Spectroscopy), also known as EDS (Energy-Dispersive Spectroscopy), is an analytical technique used to determine the elemental composition of a material. It is often coupled with scanning electron microscopy (SEM) to provide detailed information about the elemental constituents and their distribution within a sample

28. Nanoparticle Characterization: What to Measure? https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201901556 The need for robust characterization of nanomaterials for nanomedicine applications https://www.nature.com/articles/s41467-021-25584-6#Sec3 Nanoparticle Characterization Techniques https:// nanocomposix.com /pages/nanoparticle-characterization-techniques RESOURCES