Polymersomes: A New Vehicle For Gene Delivery?

A bit of reflection.

      Over all, this placement has definitely been worth it- Annabel and I have learnt many essential lab skills through dealing with much more delicate and precise equipment than what we were used to using. Particularly with the microtitrations, having good concentration was vital to make sure that we did not add more than a few drops of base at a time with the microburette to the polymer solutions.
      In addition, we were able to experience the atmosphere of a genuine research lab. Real patience and dedication is required to have a job as a lab technician or a researcher, as almost everything that happens is unexpected- we cannot predict what is going to happen next when carrying out scientific research. There were points where we came in to find that nothing had happened to the solutions, so we added a few drops of acid and then left- making our time in the lab for that day a grand total of around 20 minutes!
       However after typing up all of the results we realised that the methods we used to characterise the polymersomes proved to be effective- one or two of the experiments needed repeating though, which we would have done if we hadn’t come to the end of our 4-week placements.
            Working with PhD students has definitely inspired both Annabel and I to explore the field of scientific research in the future, if we both get into university! With this sort of experience, we have improved valuable skills that could definitely come in handy when the time comes.

The presentation went swimmingly, and now we await our certificates for our Gold CREST award! 

—Sura

(Source: polymersomes)

Preparing the presentation!

After four weeks of slaving away in the lab, we’ve finally finished our placement. We’ve spent the last couple of days preparing our presentations for the 17th. Hopefully we’ll both receive our awards after our presentations are assessed!

Repeats, repeats… and repeats

This week was spent typing up the data we had collected into excel documents and re-running the experiments which hadn’t given suitable results.

We also spent yesterday lowering the pHs of polymer emulsions.

Making more polymer solutions… And heating polymer emulsions

This week, we made more polymer solutions, this time with 5% concentration of polymer, using the same method as before.

We also tested the stability of polymer emulsions by heating and mixing them in an oil bath for 2 hours at room temperature，40°C，50°C，60°C and 70°C. After heating and mixing, the emulsions were then left alone and the time taken for each polymer emulsion to phase was noted down… Some of the emulsions took almost 3 hours to separate into phases!

Finding pKa through microtitrations

We prepared a 0.2M solution of NaOH and Milli-Q water to use for titrating our 1% polymer solutions. Unfortunately not all of the polymers were dissolved when we arrived in the lab this morning so we only titrated P1(NG6), P2(NG6), P3(NG6), P4(NG6) and P8(NG6). 

• Approximately 2g of NaOH pellets were weighed and put in a volumetric flask. 
• The flask was filled up to the mark with Milli-Q water and labelled.
• A microburette was rinsed with Milli-Q water and filled with the 0.2M NaOH solution. The initial volume of the microburette was recorded.
• A vial of one of the fully dissolved 1% polymer solutions was opened and we tested the pH with a pH metre. 
• The initial pH of the 1% polymer solution needed to be between 2.0-2.5 . If it wasn’t, 1 or 2 drops of HCl was added to bring the pH down.
• The 0.2M NaOH solution in the microburette was added drop-wise to the 1% polymer solution. After 1-3 drops each time, the pH of the 1% polymer solution was recorded and the volume on the microburette was noted down in a table. 
• This was done until the pH of the 1% polymer solution reached over 11.00.

This titration method was repeated with all of the other 1% polymer solutions that had dissolved fully.

(Source: polymersomes)

Making 1% polymer solutions

Today, after finally getting our COSHH forms signed, we began work in the lab.
Our full day consisted of preparing 1% solutions of various polymers. Each solution had to weigh ~10g which meant that in each vial, 9.9g of Milli-Q water was added to 0.1g of polymer.

• 13 vials were rinsed with acetone and placed in an oven to dry.
• After drying, the vials were left to cool down to room temperature.
• The scales were tared. A magnetic stirrer was placed in a vial, and the mass of both the vial and the stirrer were measured and noted in a table.
• With the vial still on the scales, it was tared again. 0.1g of polymer was added to the vial. The weight was noted down in a table.
• Milli-Q water was added until the scales read approximately 10g.
• The vial containing the solution was then sealed and labelled.
• This was done 13 times (for 13 different types of polymer), with the spatulas used to obtain the polymers being rinsed with acetone after each use.
• 2 drops of concentrated HCl was added to solutions P1-P9. 
• All 13 vials were placed on a hot-plate stirrer.

(Source: polymersomes)

Polymersomes: A New Vehicle For Gene Delivery?

Polymersomes are a class of synthetic vesicles formed from the self-assembly of amphiphilic block copolymers. These polymeric vesicles are hollow spheres with a hydrophobic bilayer membrane and hydrophilic internal and external coronas with size ranging from 50 nm to 5 µm or more (first image). Polymersomes have gained a lot of interest because unlike polymeric micelles they have the ability to deliver both hydrophilic and hydrophobic drugs (second image). In this study, novel methods of fabricating polymersomes using water in water emulsions will be investigated.   

Figure: first) Polymersomes picture, second) Schemicatic representation of a polymersome, based on an amphiphilic diblock copolymers.

(Source: polymersomes)