Unique ‘barcodes’ for molecules could help expedite medical advancements

Barcodes are commonly used to track items like groceries or clothing, but University of Central Florida researchers have developed a special “barcode” to identify much smaller objects: molecules.

UCF researchers, led by UCF NanoScience Technology Center Professor Debashis Chanda, developed a “barcoding” technique to quickly identify chiral molecules based on their unique infrared fingerprints, potentially speeding up pharmaceutical and medical advancements.

The molecules can be identified using a special pixelated 2D sensor array that interacts with precise light with the specific properties of the molecules to capture their unique vibrational absorptions, which are then mapped as a barcode.

The study was recently published in Advanced Materials.

Chiral molecules are pairs that are similar in structure but are twisted differently (left or right), like how a person’s left and right hands are mirror images of each other. Understanding the nature of chiral molecules is crucial to biological and pharmaceutical research because the mirror image pairs—known as enantiomers—can each have different effects in the body or in chemical reactions.

Nearly 56% of all modern drugs and medicine are chiral in nature, and about 90% of those are a mixture containing equal amounts of two enantiomers of a chiral compound. Researchers often face the challenge of separating enantiomers or synthesizing only the desired enantiomer to ensure optimal therapeutic outcomes and minimize adverse effects.

Most modern medicines and drugs are chiral and are marketed as racemates (equal mixtures of enantiomers), which in some cases can have unwanted consequences, Chanda says. This highlights the need for techniques that can identify such molecules reliably and accurately.

“On molecular adsorption, the combined system’s response depends on the degree and positional overlap of the molecule’s absorbance and sensor resonance,” Chanda says.

“The measured signal is analyzed and encoded to generate a ‘chiral barcode’ for uniquely identifying the adsorbed chiral molecule. We show applicability of the platform by analyzing and generating unique chirality-based barcodes for an enantiomeric pair of small molecules, as well as a pair of spectrally similar larger chiral biomolecules based on very low volumes of analytes at ultra-low concentrations.”

The sensing platform is made of specially engineered nanopatterned gold where the interactions between the plasmonic and photonic cavity modes produce strong chiral “superchiral” light, he says.

By changing the geometrical parameters, 25 such spectrally de-tuned sensors in a 5×5 array were produced. When a molecule is added to this array, each sensing element produces a slightly different chiral response, resulting in a unique barcode.

“Unlike other existing platforms that require chiral nanostructures of varying asymmetries that can be difficult to replicate, our proposed system’s inherent achirality overcomes this problem, greatly simplifying the fabrication process,” says Aritra Biswas, postdoctoral fellow and lead author of the paper.

“Additionally, the sensors are fabricated by simple nanoimprint lithography and two deposition steps, therefore making them very robust. We envision that such a versatile, low footprint, mass manufacturable platform would be a crucial tool for drug and biomolecular identification with applications in medical research and pharmaceutical industries.”

“We aim to contribute towards the development of inexpensive and sensitive chiral drug identification methods for chemical, biological and medical research, the fabrication of novel devices exhibiting superior light-matter interaction and the demonstration of a real product with commercial viability,” Chanda says.

Postdoctoral fellow Pablo Cencillo-Abad also contributed to the research and is listed as a study co-author.