Hello Reader, how many full trash bags have you seen these days?
Plastic waste is by far the most apparent sustainability problem in laboratories.
Nevertheless, I too often hear from scientists that they doubt they can drive significant change because of contamination risks...
Therefore, let us discover how to reduce plastic waste even in sterile conditions:
Today's Lesson: Saving Plastic Waste in Protocols
A case study of an optimized research approach
Number Of The Day
There is a lot of potential to save plastic in laboratories—even in sterile conditions. This publication demonstrates that optimizing protocols can reduce plastic use by 65% through accessible steps. Importantly, none of the changes affected sterility or processing time.Similar reports from microbiological or marine biology labs underline that it is possible to save plastic waste without fundamentally reworking running systems.
65%
A Case Study On Saving Plastics
Although we cannot eliminate plastics altogether, we can significantly reduce their waste.
This picture was taken at EMBL, showing the "4 weeks of pipetting" which contained nearly 0.5 tonnes of pipette tip boxes
To successfully enable change, we have to resolve three false beliefs:
The amount of plastic that can be saved in research is insignificant.
The kind of change required disrupts running systems.
Common plastic-saving practices are dangerous in sterile environments.
Therefore, the case study we discuss today was performed in sterile environments, saving 65% of plastic waste (35.7g per sample) without changing any of the functional aspects of the protocol.
We will focus on a standard transfection protocol for rat primary hippocampal neurons—in other words, delivering DNA into neurons grown in culture to study how synaptic connections change over time.
1. Preparation of Neurons
Neurons were transferred from their growth medium to dedicated petri dishes filled with a specifically supplemented medium (Neurobasal Medium), additionally adding 2-amino-5-phosphonovaleric acid) to suppress cell death.
The same serological pipette was used to distribute the HBSS first and then add Neurobasal Medium (from an aliquoted stock) into another set of empty plates, saving another 10.3 g of plastic waste.
Instead of adding the few microliters of cell death inhibitor to each medium containing plate, the cell death inhibitor can be pipetted first to only use one tip.
2. Preparation of DNA
DNA was diluted, then mixed with CaPO₄. Finally, both the DNA and CaPO₄ solutions were combined with a salt solution. These steps were time-sensitive due to the generation of DNA complexes.
During the preparation of the transfection solutions, first water was pipetted with one tip and then the DNA was added saving 0.329 g of plastic (a 33% reduction).
The dilution of DNA samples was conducted in PCR microtubes instead of 1.5-mL tubes, further reducing waste by 52% or 0.53 g (given that volume never exceeded 70μL)
1.5-mL tubes were used instead of 15-mL tubes for combining the DNA complex with the salt-buffer solution, resulting in an 84% reduction of 5.18 g of plastic (given that volumes never exceeded 1.2 mL)
3. Transfection of Neurons
The transfection mix was added to the neuronal cultures and incubated for 1 h.
Instead of performing each step separately, one sample was treated from beginning to end so that the same tip was used to add the CaPO₄-DNA solution to the prepared salt (HEPES) buffer and then transfer it drop-wise to the neurons. This change saved another 200 μL tip, reducing plastic waste by 0.329 g.
4. Replating
Finally, cells were washed and re-plated.
The salt solution for washing (HBSS) was directly mixed with the suppressant in dishes, avoiding the need to mix them in a 50 mL conical tube before transferring them to dishes, thereby saving 12.8 g of plastic waste. (As the solutions would be mixed by pipetting up and down and gently swirling the dishes, insufficient mixing was not a concern.)
New dishes for growth could be filled with medium during the initial preparation of the transfection dishes to use only one serological pipette. These dishes were kept in the incubator (i.e., not crowding the cabinet) to avoid temperature shocks when transferring the neurons.
To ensure the safety of these steps, assessments of neuron confluency, dendrite formation, cellular morphology, and synapse formation were conducted a few hours after plating and each day of culture. No differences were found : )
Applying The Knowledge
The essential requirement for such optimization is understanding the main purpose of each step in a protocol. In summary, optimizing item use is about streamlining for efficiency rather than convenience. The principles of miniaturization, reuse and reduction can be applied to any protocol. A full list of options will be shared in our Slack group.
Additionally, while these strategies should be implemented in any newly written protocol, it is not advisable to change steps when taking over a protocol from someone else. Instead, perform it at least twice to get a feel for the process.
Finally, speaking from personal experience, over time one will find more and more opportunities for optimization. That means there is no need to worry if, at first, one only identifies one or two possible changes. It’s about experience and learning to recognize patterns.
Nevertheless, implementing even the smallest change is critical, as it will reduce waste and build your confidence in optimizing protocols.
Upcoming Lesson:
Freezer Sustainability
How We Feel Today
References
Penndorf, P., 2024. Reducing plastic waste in scientific protocols by 65% - practical steps for sustainable research. FEBS Lett., 598(11), 1331–1334. doi:10.1002/1873-3468.14909. Alves, J., et al., 2020. A case report: insights into reducing plastic waste in a microbiology laboratory. Access Microbiol., 3(3), 000173. doi:10.1099/acmi.0.000173.
Kilcoyne, J., et al., 2022. Reducing environmental impacts of marine biotoxin monitoring: A laboratory report. PLOS Sustain. Transform. doi:10.1371/journal.pstr.0000001.
Penndorf, P., Jabs, J., 2023. A new approach to making scientific research more efficient - rethinking sustainability. FEBS Lett., 597(19), 2371–2374. doi:10.1002/1873-3468.14736.
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