Analysing cells and culture media with surface-enhanced Raman scattering (SERS): how to overcome the serum protein problem?


Elodie Dumont, CIRM, VibraSante HUB, Department of Pharmacy, University of Liege, Liege, Belgium (elodie.dumont@uliege.be)
Charlotte De Bleye, Cirm, Vibrasante Hub, Department Of Pharmacy, University Of Liege, Liege, Belgium
Johan Cailletaud, Cirm, Vibrasante Hub, Department Of Pharmacy, University Of Liege, Liege, Belgium
Philippe Hubert, Cirm, Vibrasante Hub, Department Of Pharmacy, University Of Liege, Liege, Belgium
Eric Ziemons, Cirm, Vibrasante Hub, Department Of Pharmacy, University Of Liege, Liege, Belgium

Surface-enhanced Raman scattering (SERS) has become a valuable tool in the pharmaceutical and bioanalytical fields as it presents numerous advantages making it competitive towards other analytical tools. This vibrational spectroscopy technique is indeed specific with multiplex capabilities while requiring little sample preparation and being non-destructive. SERS is also very sensitive, benefiting from the exaltation of the Raman signal of analytes located in the vicinity of or adsorbed onto rough metallic surfaces called the SERS substrates. These substrates can be in the form of suspensions of nanoparticles or of nanostructured solid substrates, increasing the versatility of the technique.

However, a current challenge faced in biological SERS is the protein corona problem [2]. It arises from the adsorption of serum proteins onto the SERS substrates, preventing the adsorption of the analytes themselves onto the substrates. Moreover, when the SERS substrate is a suspension of nanoparticles, the protein corona stabilises the latter, resulting in a lack of aggregation.

In order to circumvent these problems, when working with a suspension of nanoparticles, the colloid can be pre-aggregated before adding the serum sample [3], therefore bypassing the stabilisation issue. On the other hand, regarding solid SERS substrates, the challenge rather concerns avoiding the adsorption of proteins onto the substrate since the nanoparticles are already set in a fixed configuration.

To that end, membranes with a low molecular weight cut-off (MWCO) have been employed. These membranes could let small molecules diffuse through them while retaining proteins of larger sizes. Indeed, the main protein component of serum is albumin, which has a molecular weight of 66 kDa [4].

Rat phaeochromocytoma PC-12 cells were selected as model to investigate the potent of these membranes. PC-12 cells mainly synthesise dopamine, a neurotransmitter of great physio-pathological importance and having a native affinity for the surface of gold nanoparticles [3]. They were cultured on inserts and their exocytosis of dopamine was followed by SERS with the help of membranes. Different analysis configurations were studied, with the SERS substrates located inside or beneath a dialysis membrane or a filter.

In conclusion, the use of dialysis or filter membranes seems extremely promising in the field of SERS bioanalyses of complex matrices.


References

[1] E. Dumont et al., Bioanalysis, 8(10), 2016, 1077-1103.

[2] J. Taylor et al., Analyst, 141, 2016, 5037-5055.

[3] E. Dumont et al., Talanta, 186, 2018, 8-16.

[4] A. Sasidharan et al., J. Mater. Chem. B, 3, 2015, 2075-2082.



Abstract Reference & Short Personal Biography of Presenting Author

Elodie Dumont graduated in Pharmaceutical Sciences at the University of Liege in Belgium in 2015. She is currently a PhD student in the Laboratory of Pharmaceutical Analytical Chemistry of the Professor Philippe Hubert at the University of Liege. Her PhD thesis, funded by the Belgian National Fund for Scientific Research (F.R.S.-FNRS), is focussed on the development of SERS nanosensors for the detection of small bioactive molecules in biological matrices. She had the opportunity to attend last DA-PBA 2018 symposium in Leuven where her presentation about “A simple and easy-to-implement SERS approach overcoming the nanoparticle stabilisation by serum proteins: application to dopamine and PC-12 cells” was rewarded by the Young Scientist Prize

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