# Screening of specific aptamers for Bacillus cereus by Surface Plasmon Resonance imaging (SPRi)

Mathilde Manceau, Carole Farre, Florence Lagarde, Raphaël Mathey, Arnaud

Buhot, Jasmina Vidic, Yanxia Hou, Carole Chaix

► To cite this version:

Mathilde Manceau, Carole Farre, Florence Lagarde, Raphaël Mathey, Arnaud Buhot, et al.. Screening of specific aptamers for Bacillus cereus by Surface Plasmon Resonance imaging (SPRi). SNOSCELLS Ecole Thématique CNRS, Jan 2023, Les Houches, France. hal-03977223

HAL Id: hal-03977223

https://hal.science/hal-03977223

Submitted on 7 Feb 2023

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Distributed under a Creative Commons Attribution 4.0 International License
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Mathilde Manceau
2nd year PhD student

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Lyon 1

# Screening of specific aptamers for *Bacillus cereus* by Surface Plasmon Resonance imaging (SPRI)

Mathilde MANCEAU¹*, Carole FARRE¹, Florence LAGARDE¹, Raphaël MATHEY², Arnaud BUHOT², Jasmina VIDIC³, Yanxia HOU-BROUTIN², Carole CHAIX¹,*

¹ Institut of Analytical Sciences, UMR 5280 CNRS, University of Lyon, University Claude Bernard Lyon 1, 69100, Villeurbanne

² University Grenoble Alpes, CEA, CNRS, IRIG-SyMMES, 38300, Grenoble

³ INRAE, AgroParisTech, Insitute Micalis, University Paris-Saclay, 78350, Jouy-en-Josas

* mathilde.manceau@isa-lyon.fr ; carole.chaix-bauvais@univ-lyon1.fr

## INTRODUCTION

**Bacillus cereus** is a **food poisoning** bacterium present in dairy products. To detect it, antibody based biosensors are efficient but available antibodies are expensive and may cross-react with other *Bacillus* species. **Aptamers** are a good alternative to these issues. Herein, seven aptamer sequences derived from the literature(1,2) are **compared** and their specificity to *B. cereus* is assessed versus *Escherichia coli* and *Bacillus subtilis* by **Surface Plasmon Resonance imaging (SPRI)**.

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## GRAFTING STRATEGY

Two grafting strategies were explored: the EDC/NHS reaction was carried out on either a **11-mercaptoundecanoic acid (MUA)** or **HS-C₁₁-EG₆-OCH₂-COONHS (PEG)** self-assembled monolayer (SAM).

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Conclusion and
perspectives

Aptamer **affinity** towards *B. cereus* was explored by **cumulated injections** of its nanosomes.

**Specificity** is assessed versus *E. coli* and *B. subtilis*.

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## RESULTS

The aptamers **SP15L** and **SP15M** show the **higher affinity** for *B. cereus* and they contain both the

**G-quadruplex**. SP16S, M and L have a lower affinity for *B. cereus*.

The **higher the aptamer density**, the **better the specificity** seems to be.

The truncated aptamer SP15M showed good affinity for *B. cereus* nanosomes. A sequence containing only the G-quadruplex will be tested. Nanosomes will be further characterized by Cryo-TEM and NTA.

## MATERIALS AND METHODS

### SPRi principle:

**Surface plasmon** is an electromagnetic wave at the surface of a thin layer metal - here gold - generated when polarized light hits the surface. At a **specific incidence angle**, the plasmon waves resonate with the incidence light resulting in a **dip of reflectivity**: it is the **resonance** peak.

Variations of this thin angle correspond to changes on the biochip surface.

### Design of aptamers:

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<figure><img src="image_11.png" /><figcaption>SP15¹</figcaption></figure>

<caption>SP16¹</caption>

<caption>Zheng²</caption>

Aptamers from literature(1,2) were **truncated** according to their **2D structure** and their melting temperature and **stability** using mFold software.

A 5' **amine modification** and a **polyThymidine (pT6) spacer** were added to respectively allow aptamer grafting and structuration on gold functionalized surface.

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**Nanosomes:**
To increase the sensitivity, bacteria membranes are fragmented in vesicules of about 200 nm which are called nanosomes.

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