Hydroxyapatite is the premier building block for biomineralized tissues. It come
ID: 178206 • Letter: H
Question
Hydroxyapatite is the premier building block for biomineralized tissues. It comes in many sizes, shapes, and flavors based on how it was made (synthesis conditions) and what its intended purpose is (structural reinforcement, mineral storage bank, etc). In order to better understand its vital role in hard tissue (bone and teeth) as well as an additional assortment of biologically relevant subjects such as cancer metastasis, biological activity and adsorption phenomena related to ECM, pathological calcification, etc, it is imperative to be able to measure fundamental properties related to its chemical and physical properties as well as navigate within its time and space domain to unravel the intricacies and mysteries of its structure and purpose. Imagine that you partner with Antman and you co-develop a machine that allows you to shrink to atomic scale dimensions and you are able to move within a single crystal of HAp. Imagine what you would be able to see and experience as you navigate throughout the crystal and measure the boundaries of the crystal? Please answer the following questions regarding hydroxyapatite. Please How many atoms are in the unit cell for Hap? What are the unit cell parameters? Calculate the unit cell volume for HAp. Calculate the density for HAp. Calculate the packing factor for HAp. Derive an equation for calculating the specific surface area for hydroxyapatite particles consisting of unit cell dimension particles. Calculate the value for the specific surface area of these particles. How would you differentiate between a polycrystalline, a single crystalline, and a nanocrystalline sample of Hap? Please mention the technique and briefly describe why it would work. calculate the packing factor for the octahedral structure that would be found in a hypothetical composite body centered/face centered cubic unit cell.Explanation / Answer
a. Hydroxyapatite (HAp) is a calcium phosphate.
44 atoms we used a 6 × 6 × 8 grid of k points (288 points), 44 atoms are present in the unit cell of HA P, which include 10calcium atoms 6 (PO4) tetrahedral, and 2OH-groups that are all organized in to a hexagonal structure.
b)Basic building block of a crystal, is the unit cell. The Unit Cell Parameters are a,b,c are three vectors and angles between the vectors are alpha, the angle between b and c; beta, the angle between a and c; gamma, the angle between a and b
c. Unit cell volume for hexagonal =V = a2c sin(60°)
a = b = 9.4732 Å and c = 6.9989 Å for equilibrium HAp unit cell parameters
V=9.47322X6.9989 sin (60)=-191.43 Å
d. Theoretical density (T.D.) of HAp. 50 nm , experimentally measured density values with 3.16 g/ccm, HAP density (r=0.87).
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