Page 37 - ITU Journal Future and evolving technologies Volume 2 (2021), Issue 3 – Internet of Bio-Nano Things for health applications

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 3

ENABLING MOLECULAR COMMUNICATION THROUGH CHIRALITY OF ENANTIOMERS

1
Valeria Loscrı́ and Anna Maria Vegni 2
1 Inria Lille ‑ Nord Europe, Lille, France, Roma Tre University, Rome, Italy
2
NOTE: Corresponding author: Valeria Loscrı́, valeria.loscri@inria.fr

Abstract – With the advancement of nanotechnology, there has been fervid research activity on new communication
paradigms suitable for new challenging contexts, such as biological systems. Among different approaches, the most
considered has been arti icial Molecular Communication, where entities such as synthetic molecules, enzymes, hormones,
bacteria etc. are functionalized in order to implement information exchange with the surrounding system and with other
entities. In this context, it is interesting to analyze speci ic features that could be exploited for effective communication
paradigms. In this paper, we focus on chiral molecules (a.k.a. enantiomers) as novel enablers for a molecular commu‑
nication paradigm. Chirality is an interesting and appealing feature existing in nature and that can be replicated with
strong emphasis in new types of materials, such as metasurfaces and metamaterials. A deep knowledge of chirality fea‑
tures and how chiral molecules interact with each other or with achiral molecules provides insights into designing a new
molecular communication technique suitable for biological environments. In this contribution, we will highlight the main ap‑
plications of chiral molecules and we will present chiral features as the viable way for realizing a nanocommunication system.

Keywords – Chiral molecules, chirality transfer, enantiomers, molecular communications, optical activity

1. INTRODUCTION means of guided bacteria or catalytic nanomotors is rela‑
tively very slow (i.e., a few millimeters per hour).
A Molecular Communication (MC) paradigm consists of
using molecules to encode, transmit and receive infor‑ A special type of molecules that is expected to be very
mation. It has recently received a lot of attention by promising in the ield of molecular communications is the
the research community since it is considered as the chiral molecule. Chiral molecules show the chirality effect
viable alternative of electromagnetic (EM) communica‑ i.e., a physical phenomenon that pervades the universe.
tions, thanks to the speci ic features of biocompatibility. The term chirality was introduced in 1884 and refers to
MC is mostly inspired by existing communication mecha‑ objects that are not equivalent to their mirror images, and
nisms occurring between biological entities and is devel‑ the two images are not superposed to each other. A typ‑
oped by considering small molecules, peptides, lipids, as ical example of such a geometrically chiral object is the
well as bacteria, viruses, pheromones and so on [1]. human hand, so that the left and the right hands are mir‑
ror images of each other, but it is impossible to superpose
An MC paradigm is based on the transmission and recep‑ them.
tion of information encoded into molecules (i.e., messen‑
ger molecules) [2, 3]. These entities freely propagate in Chiral molecules, a.k.a. enantiomers, can show their dif‑
the medium by connecting a transmitter with a receiver ferent handedness in many ways, including the way they
nanomachine. Typical molecular communication systems affect human beings. For instance, one enantiomeric form
are based on the free diffusion process of molecules, such of a compound called limonene is primarily responsi‑
as calcium signaling, microtubules, pheromone signal‑ ble for the odor of oranges, while the other enantiomer,
ing, and bacterium‑based communications [4]. Different for the odor of lemons. Molecules of the amino acids
biological entities allow reaching different communica‑ of which our proteins are built have the property of be‑
tion ranges and performance. For instance, the use of ing non‑superposable on their mirror image. In contrast,
pheromones (i.e., molecules of chemical compounds re‑ objects (and molecules) that are superposable on their
leased by plants, insects, and other animals) triggers spe‑ images are achiral. The chirality of molecules can be
ci ic behaviors among the receptor members and reaches demonstrated with relatively simple compounds. For in‑
long‑range communications i.e., approximately one me‑ stance, consider a 2‑butanol molecule i.e., an organic com‑
ter. On the other side, both lagellated bacteria and cat‑ pound with formula CH CH(OH)CH CH . The structure
3
2
3
alytic nanomotors are able to carry DNA messages and of 2‑butanol is chiral, that means that there are actually
allow short‑range communications. The use of DNA as two different 2‑butanols and they are enantiomers. An‑
information messages allows achieving an information other example is the amino acid alanine, which is in the
rate that is relatively high (i.e., up to several kilobits per form of left‑handed and right‑handed enantiomers i.e.,
second). In contrast, the propagation of information by (S)‑alanine and (R)‑alanine, respectively. Fig. 1 depicts

© International Telecommunication Union, 2021 25