Team:Uppsala/HP/Silver

The Price of Transformation

We manufactured prototype transformation chips in order to evaluate the efficiency of the chips created with our method. As the method was developed to be as accessible as possible, especially to smaller labs, we also wanted to check how cost efficient microfluidics could be. We therefore calculated an approximate cost for the conventional transformation procedure that we used, as well as the cost for the transformation procedure using a chip. This showed that in theory, even a simple procedure such as transformation can be cheaper using microfluidics. With that in mind, imagine how much a low budget lab could save by simplifying a more comprehensive procedure with microfluidic chips manufactured using our method.

The cost of the chip itself was calculated based on the price of the required materials. Equipment such as the 3D-printer and pumps is not included as they are fundamental for the accessibility of the method, and usually available at universities. The chip is also calculated to last indefinitely, which is possible in theory for this evaluation as PDMS should last over two years and due to the chips being washable. However, in practice, the prototype chips could only be used a limited number of times due to human intervention, which should be solved before final application.

Table 1: Displays the costs and usage of the required materials to create one of our microfluidic chip, as well as the summarized cost per chip. All costs were first calculated in SEK and then converted into Dollars. The price for Mold Resin were taken from the Formlabs webpage, while the PDMS price were from Sigma-Aldrich . Plexiglas was bought from a local hardware store.

Chip cost	Reagent	Reagent amount needed	Price for amount ($)
7.968 $/chip	Mold Resin	7.29 mL	0.1301
	PDMS	1/3 bag	7.612
	Plexiglas	2x5 cm2	0.2262

The protocol that we used to perform transformations on E. coli was the protocol from “Synthetic Biology: A lab manual”. The cost of transformation was therefore based on the price for all the materials required according to that protocol combined with observed usage of additional equipment such as pipette tips and gloves. When the price for all specific materials had been noted, the transformations were divided into three different types, Conventional Heat shock, Prototype Heat shock Chip and Optimal Heat shock Chip. The Conventional Heat shock is the cost for an average heat shock transformation according to the lab protocol. The prototype Heat shock Chip transformation cost is based on the usage of materials for the tests of our prototypes. The last type, Optimal Heat shock Chips is based on what we viewed as possible easy improvements if we kept working with the chips beyond this prototype.

Table 2: The cost of performing conventional heat shock transformation based on the material usage in protocols and in lab observations. All costs were first calculated in SEK and then converted into Dollars. Solutions that were mixed ourselves were priced based on their material cost. All these materials were bought throught the university, which means that we based our calculations on their cost estimate.

Conventional Heat shock:	Reagent	Price per unit	Reagent amount needed	Price for amount ($)
2.045 $/Transformation	SOB media	2.324 $/L	950μL	0.002208
	LB plates	1.198 $/plate	1 plate	1.198
	DNA	0.1176 $/μL	1μL	0.1176
	Competent cells	0.3518 $/50μL	50μL	0.3518
	Pipette tips	0.01923 $/pc	4 pc	0.07692
	Gloves	0.1923 $/pair	1 pair	0.1923
	eppendorf tube	0.1063 $/pc	1 pc	0.1063

Table 3: The cost of performing our prototype heat shock transformation based on the material usage in our proof of concept tests.

Prototype Heat shock:	Reagent	Price per unit	Reagent amount needed	Price for amount ($)
1.659 $/Transformation	SOB media	2.324 $/L	100μL	0.0002324
	LB plates	1.198 $/plate	1 plate	1.198
	DNA	0.1176 $/μL	0.5μL	0.0588
	Competent cells	0.3518 $/50μL	5μL	0.03518
	Pipette tips	0.01923 $/pc	3 pc	0.05769
	Gloves	0.1923 $/pair	1 pair	0.1923
	eppendorf tube	0.1063 $/pc	1 pc	0.1063

Table 4: The cost of performing a possible optimal heat shock transformation based on what we thought would be easy to remove in microfluidic chips beyond our prototype.

Optimal Heat shock:	Reagent	Price per unit	Reagent amount needed	Price for amount ($)
1.418 $/Transformation	SOB media	2.324 $/L	100μL	0.0002324
	LB plates	1.198 $/plate	1 plate	1.198
	DNA	0.1176 $/μL	0.5μL	0.0588
	Competent cells	0.3518 $/50μL	5μL	0.03518
	Pipette tips	0.01923 $/pc	1 pc	0.01923
	eppendorf tube	0.1063 $/pc	1 pc	0.1063

Based on the costs for each type, combined with the chip cost for the microfluidic based methods, our prototype method becomes more profitable at 21 or more transformations, while the Optimal method becomes more profitable after only 13 or more transformations.

Table 5: The results from the calculations to evaluate the amount saved when performing chip based transformation, compared to the conventional method. Fourth column shows the approximate costs for 500 transformation, while the fifth column shows the cost difference between 500 conventional transformation compared to each chip based method.

Heat Shock Calculation	The Cost	Cheaper than Conventional	Summer Cost ($)	Conv. to Chip Summer Diff. ($)
Conventional	Cost = 2.045xTransformations		1022.5
Prototype Chip	Cost = 1.659xTransformations + 7.968	#Transformations>20	837.5	185
Optimal Chip	Cost = 1.418xTransformations + 7.968	#Transformations>12	717	305.5

In order to get a better view of how much the microfluidic based transformation methods saves, we approximated how much we could have saved this summer if all of our transformations had been performed using a chip. Based on our competent cell usage we performed around 500 transformations this summer. This means that we get the summarized costs seen in the tables below, which means that we could have saved over 300 dollars this summer by using an optimal chip!

Heat shock transformation is a fairly simple lab procedure, yet microfluidics could potentially decrease its cost enough for us to finance all of the coffee consumed in our lab this summer, which is quite an impressive feat. Microfluidics has the ability to simplify other, much more extensive, lab procedures. This would in turn save even more money than the fair amount saved by our microfluidic chip, which could potentially be used for more lab work, the planting of trees or/and to finance fika*!

*Swedish ritual involving the consumption coffee and some sort of baked treat.