Demo: Preparation + QC of Compounds for Hyperpolarization

Transcription

1 Demo: Preparation + QC of Compounds for Hyperpolarization 3/23-24/17 etup: 1. Gather materials: a. Millipore water b. Glycerol c. DMO d. N,N- dimethylacetamide e. 10 M NaOH f. Vortex g. Heat gun h. mall glass bottles i. LN2 bucket j. Tongs 2. Ensure the following are printed out: a. adical printout (one copy) b. Agent prep flowchart (enough copies to hand out) c. HP QA process (enough copies to hand out) 3. Obtain LN2 just prior to demo Lesson plan: 1. [Get an idea of what people are interested in learning about:] a. What HP compounds are of interest? b. More interest in HP formulation procedure, or QC process? c. Other agent characterization techniques? Part I: Basics of HP Formulation 2. Discuss: requirements of a good HP agent [ask!] a. eports on biologically relevant process (metabolism, enzyme activity, etc.) b. Highly soluble, or neat liquid at room temperature c. Long T1 13 C nucleus d. apid biodistribution (+ uptake) e. Low toxicity at physiological concentrations (1-50 mm) f. Good stability at high concentration 3. Discuss: how HP works a. 13 C compound + lone electron (radical), polarize e - by cooling, transfer polarization to 13 C nuclei using microwaves b. equirements of a good HP formulation [ask!] i. High concentration: 1-2 M minimum ii. Forms a glass at cryogenic temperatures iii. Dissolves mm trityl radical iv. Agent remains stable within formulation 4. [Demo: crystallization (water) vs. glassing (glycerol)] 5. Discuss: solvents - H2O, glycerol, propylene glycol, DMO, DMA, EtOH a. Differences (especially solubility) b. Using solvents as glassing agents

2 6. Discuss: process flow of making a HP formulation for a new agent [handout: agent prep flowchart] Part II: Quality Assurance of Formulated Agents 7. Discuss: QA procedure for a new HP formulation [handout: HP QA process] a. Important parameters to measure: MW freq, buildup max, buildup time constant, dissolution ph, T1, % polarization, agent concentration Part III: Advanced HP Formulation trategies 8. [Open discussion: new approaches to formulation + dissolution] a. Influence of [radical], [Gd- DOTA] b. Use of Ho- DOTA vs. Gd- DOTA (J. Gordon, D. herry) c. Effects of solvent 2 D/ 13 C- labeling d. Narrow- EP radicals: BDPA e. Byproduct minimization: adding radical just before polarization, 2 eq NaOH (Gln, K. Keshari) f. 13 C micropowder + EPA solution strategy (wiss group) g. ingle- formulation copolarization: dissolve an agent in [ 13 C]pyruvic acid? h. CIMP: [ 13 C]pyruvic acid, [1-13 C]GLC (. izi, D. Korenchan) i. Others?

3 Trityl adicals a. The stabilized trityl radicals used as the source of spin polarization are costly and must be stored and handled properly. They are best stored long term cold, dry and protected from light, e.g. in a jar containing a dessicating agent in the freezer. To prevent the buildup of water condensation, allow them to warm to room temperature before handling. The trityl radicals are typically light, lyophilized solids of various shades of green. To reduce their tendency to cling to surfaces when handling them, it helps to use an antistatic gun to dissipate static electricity on the plasticware and weighing containers. b. The structures and molecular weights of the radicals: CO 2 Na NaO 2 C CO 2 Na = Name Formula Molecular Weight - CH2CH2OH OX- 63 C52H60Na3O CH2CH2OCH3 GE Trityl / AH- C64H84Na3O CH3 Finland C40H36Na3O

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5 Quality Assurance (QA) Procedure for HP Formulations Microwave sweep, polarization buildup: 1. Load µl of HP formulation into Hyperense cup, load into polarizer 2. Perform microwave sweep to obtain polarization frequency a. tart with these parameters: 300 min buildup time, 100 MHz sweep width, 25 mw power b. ecommended to do a coarse frequency sweep (5 MHz resolution) to capture full lobe of sweep curve, then do a fine frequency sweep (2-3 MHz resolution) to identify maximum c. If polarizer contains background signal, perform a sweep using same parameters prior to loading sample d. Perform routine sweeps every 2-3 months 3. emove sample from polarizer to recover 4. Load µl of HP formulation into Hyperense cup, load into polarizer 5. tart polarization at optimal microwave frequency, monitor buildup using INM program a. Note the following parameters, compare with previously- acquired values: i. Microwave frequency ii. Buildup curve maximum iii. Buildup curve time constant HP dynamic 13 C- NM spectroscopy to measure % polarization, T 1: 6. Prepare NM spectrometer for HP polarization + T 1 measurement: a. Insert sample with similar ionic strength, tune coils ( 1 H, 13 C) and shim b. etup arrayed 13 C sequence, verify that it runs properly i. Ensure the following parameters are set properly: 1. pectral width 2. Transmit + receive frequency 3. Pulse width + power (5-15 ) c. Prepare system to start upon hitting Enter key 7. Prepare empty NM tube with cap for measurement 8. Prepare polarizer for dissolution, inject dissolution buffer, dissolute 9. Quickly inject HP dissolution into NM tube, insert into spectrometer, start sequence a. Use timer to record transfer time from polarizer to spectrometer b. ave data once acquisition finishes Thermal 13 C- NM spectroscopy to measure % polarization, concentration: 10. Apply 5-9 hard 90 pulses to saturate remaining HP signal 11. etup NM spectrometer using the following parameters a. T = 5 * T 1 (measured in HP dynamic spectra) i. Alternatively, add 1/100 volume of 500 mm Gd- DOTA to reduce required T b. Tip angle = 90 c. # of averages = 8-32 (depending on final agent concentration in dissolution) 12. tart acquisition, save once finished Calculation of T 1, % polarization 13. For T 1: fit HP dynamic peak integrals to exponential decay a. Tip angle correction: multiply each nth transient by sec α!!!, where α is the tip angle 14. For % polarization (P!" ): use the peak integrals in (a) the 1 st HP spectrum (!" ); and (b) the thermal spectrum (! ), using the following equation: ħ!!!!!! P!" = P!!"! csc α a. P! = tanh!! is the polarization at the NM spectrometer field strength b. Depending on the NM spectrometer,! may need to be normalized by the # of averages c. The back- calculated % polarization to the time of dissolution is often reported, assuming constant T 1 loss over the transfer time (t!"#$%&'" ). This is calculated as P!",!"#$!!"#!$#"%&' = P!" e!!"#$%&'"!!