Nanobiotechnology Readings and Viewings

The Chemistry of Glass and Glass-Like Materials in Biotechnology

You many find the Cademartiri and Ozin chapter challenging, if you need to brush up on some of the chemistry.The chemistry of glass and glass-like materials is important in many biotechnology applications and research.A lot of science and technology, from semiconductors to paints and coatings, is based on the chemistry shown in Figure 2.1.You might note how versatile glass is with regard to attaching molecules.‘Functionalized’, i.e., coated with specific molecules, glass slides are used in many biomedical studies.  One theme of this course is that many materials can be made biospecific by coating them with antibodies, nucleic acids, and other biomolecules.Also covered are colloids.Colloids are an old branch of chemistry.Colloid chemistry was ‘rebranded’ as a nanotechnology as nano became ‘hot’.You’ll see lots of examples of this,

E.g., Langmuir-Blodgett (monolayer) films, zeolites, metals with nano-sized grains, etc… have been around for decades but are all considered part of nanotechnology.  ‘Wet chemistry processes’ (i.e., liquid phase in a beaker) such as the Stöber process, are commonly used to generate nanoparticles. One subtlety is adjust the process to keep the nanoparticles from clumping together, which would obviate their function. Also, note in Figure 2.2 the plot of polydispersity.  This is a problem with many nanosynthesis processes: You get a range of sizes, but for many applications you need to control the size range very precisely.The templating shown in Figure 2.3 is a common trick to form nanostructures of various materials. 

Mesoporic silica has incredibly high surface areas.  This is a common feature exploited in many nanomaterials. The self-assembly in Figure 2.4 is remarkable.  It is reminiscent of how crystals grow on an atomic scale, yet here the “crystals” (i.e., ordered arrays or stacks) are being formed from 100 to 400-nm diameter silica spheres.  

-Problem 4.13 (a simple example calculation of Bragg’s Law).Background:Roentgen discovered X-rays in 1895.  It was not certain what x-rays were.  In 1912, the suggestion and demonstration by von Laue, Friedrich and Knipping that crystals would diffract x-rays showed that 1) solids are crystals comprised of atoms or molecules arranged periodically in 3 dimensions,   2) x-rays are short wavelength electromagnetic radiation with a wavelength comparable to the spacing of atoms in the crystal, 3) crystals would diffract x-rays in predictable ways, and 4) the diffraction pattern of the crystal could reveal the crystal structure on an atomic level.  

The father and son team of WH Bragg and WL Bragg devised the method of this problem to determine the spacings beween layers of atoms or molecules in a crystal.  

1. Mendelson Chapter 4 end-of-chapter problems (pp. 219-221) Problems 4.1, 4.3, 4.7, and 4.9.

2. From Cademartiri and OzinConcepts of Nanochemistry questions from sec. 9 “Silica-Food for Thought” (pp. 79-82), respond to question topics: 1, 10, 11, 16, 19, and 20.

3. From article by Hemmer et al.“Lanthanide-based nanoparticles…”

4. What is the “biological window” of the electromagnetic spectrum and what is its significance?

5. Most materials exhibit a longer emission wavelength than excitation wavelength.  Up-converters are highly unusually.  How so?  And why is this useful?

6. How could  cancer surgeons use these nanoparticles in their work?

7. What are the fate (according to size) of these nanoparticles injected into a rat?

8. The nanoparticles are made out of an oxide (Gd₂O₃).  The impurities (dopants) in this host Gd₂O₃host crystal are Er³⁺ and Yb³⁺. What are the purpose of these dopants? 

 Note:  “Impurity” usually has negative connotations, but when impurities are intentionally added to a material to change its (e.g., electrical, optical, or magnetic) properties, the impurities are often referred to as “dopants”.  

9. The nanoparticles are often coated,with what materials and for what purposes?