Encoding Information into Polyethylene Glycol Using an Alcohol-Isocyanate "Click" Reaction.

Lajos Nagy,Tibor Nagy,Sándor Kéki,Bence Vadkerti,Miklós Zsuga,Zoltán Erdélyi,Levente Kárpáti,Ákos Kuki

doi:10.3390/ijms21041318

Abstract

In this article, the capability of encoding information using a homologous series of monodisperse monomethoxypolyethylene glycols (mPEG), with a number of ethylene oxide units ranging from nEO = 5 to 8, and monodisperse linear aliphatic isocyanates containing a number of CH2 units from 3 to 7, is demonstrated. The “click” reaction of the two corresponding homologous series yielded 20 different isocyanate end-capped polyethylene glycol derivatives (mPEG-OCONHR) whose sodiated adduct ion’s nominal m/z values spanned from 360 to 548, providing an average ca. 8 m/z unit for the storage of one-bit information. These mPEG-OCONHR oligomers were then used to encode information in binary sequences using a 384-well MALDI sample plate and employing the common dried-droplet sample preparation method capable of encoding 20 bit, i.e., 2.5 byte information in one spot, was employed. The information stored in the spots was read by MALDI-TOF MS using the m/z value of the corresponding mPEG-OCONHR oligomers. The capability of the method to store data was demonstrated by writing and reading a text file, visualizing a small picture and capturing a short audio file written in Musical Instrument Digital Interface (MIDI) sequence. Due to the very large similarities in the chemical structures of the encoding oligomers and their “easy to be ionized” property, as well as their very similar ionization efficiencies, the MALDI-TOF MS signal intensities from each compound was so strong and unambiguous that complete decoding could be performed in each case. In addition, the set of the proposed encoding oligomers can be further extended to attain higher bit “densities”.

Highlights

The need for encoding and decoding information for safety, communication or any other reasons such as storage of data is almost as old as humankind itself
Focusing on the family of compounds that are combinations of two homologous series, e.g., copolymers or the present monomethoxypolyethylene glycols (mPEG)-OCONHR oligomers, the accessible m/z range can be given by Equations (1) and (2)
Oligomers obtained by the reaction of monodisperse monomethoxypolyethylene glycol and alkylisocyanate with varying chain lengths were used to encode information in the spots of a MALDI sample plate

Summary

Introduction

The need for encoding and decoding information for safety, communication or any other reasons such as storage of data is almost as old as humankind itself. DNA is the highest capacity natural macromolecule so far capable of storing information as high as 455 exabytes/gram but encoding information in DNA, especially in the case of long strands, is a very slow, complex and expensive process [6,7,8,9] Another approach, similar to encoding in DNA, is based on synthetic copolymers in which information is encoded into the sequence of the comonomers [10,11,12,13,14,15] and the information is read by mass spectrometric methods, other strategies for encoding molecules and reading have been reported [16,17]. The resulting oligomers containing urethane bonds are structurally very similar to each other and their m/z values reveal the combination of 44 and 14 mass units The capability of this approach to store data was demonstrated by writing and reading a text file, visualizing a small picture and capturing a short audio file written in Musical Instrument Digital Interface (MIDI) sequence

Results and Discussion

The Relative Ion Intensities of mPEG-OCONHR Oligomers

Storing Information in mPEG-OCONHR Oligomers

Reading Information by MALDI-TOF MS

Conclusions