biosensors lecture 9

spectrophotometry

what is a spectrophotometers and what does it do?

type of light sensor that measures the average intensity of light signals for a range of wavelengths

photometry

measure at a specific wavelength

spectrometry

scans through a range of wavelengths resulting in a spectrum curve

components of the simplest spectrometer setup

Focusing mirror

Grating 

Collimating mirror

Absorbance based detection

absorbance is related to the concentration of a specific component

standard curve is absorbance vs concentration

convert 1 nM of PSA (26kDa) into mass concentration

26 ng/ml

4 ng/ml of PSA into Molar concentration

.154 e-9 mol/L

how does spectrometry work

scan wavelength using a mechanical rotator, a moving prism, and/or mirrors

what is Hemoglobin

red globular proteins

molecular weight of hemoglobin

64,500 Da

how much of the weight of a red blood cell is comprised of hemoglobin

almost 1/3rd

primary function of hemoglobin

carriage of oxygen from the lungs to the tissues

components of hemoglobin

1 globin and 4 heme groups

central dogma

describes the one-way flow of genetic information within a biological system: DNA makes RNA, and RNA makes protein. It explains how inherited DNA instructions are transcribed into RNA and then translated into functional proteins, which dictate cellular traits.

what is DNA

a set of instructions for creating the proteins that make your body work

4 bases of DNA

thymine

adenine

cytosine

guanine

base pairs

A- T

C- G

what is RNA

fundamental biomolecule that plays a central role in various biological processess including:

• protein synthesis

• gene regulation

• cellular communication

messenger RNA

mRNA carries the protein blueprint from a cells DNA to its ribosomes

transfer RNA

tRNA carries the appropriate amino acids into the ribosomes

where does transcription happen

in the nucleus

causes of anemia (low hemoglobin)

• loss of blood (surgery, traumatic injury)

• bone marrow problems

causes of high hemoglobin levels

• advanced lung diseases

• certain tumors

what does a pulse oximeter measure

oxygen saturation in blood (SpO2)

heart rate (pulse)

what signal does a pulse ox measure

measures absorbance signals (red and IR) of hemoglobin through a human tissue (usually finger)

how does a pulse ox work

measures absorbance at 660 nm (red) and 940 nm (IR) to estimate the ratio of oxygenated hemoglobin against the total hemoglobin amount

how does a pulse ox measure oxygen

signals are pulsating, which can be used to measure the heart rate

what is an optical fiber

transmission cable for optical signal

types of optical fibers

single mode

multimode

single vs multimode core which supports more modes

multimode has wider core

refractive index of core vs cladding

n_core > n_cladding

n gradually changes for multimode

what are biomarkers found in

biological molecules found in blood, other body fluids, or tissues

what do biomarkers indicate

presence of progression of a disease, health condition, or response to a treatment

blood vs plasma vs serum

plasma is a component of blood, serum is a component of plasma

components of blood

55% plasma

45% red blood cells ‘

<1% WBC’s and platelets

what is serum

the remaining liquid after blood has clotted and clotting factors are consumed