Aptamers for SARS-CoV-2: Isolation, Characterization, and Diagnostic and Therapeutic Developments

In this review, we are proud to share the incredible work done globally in developing aptamers for the COVID-19 pandemic. Given their desirable characteristics as molecular recognition elements, nucleic acid aptamers were of significant interest to multiple labs worldwide over the past few years. Our review paper features a comprehensive comparison between the most notable SARS-CoV-2 aptamers, taking a detailed look at the SELEX strategies, sequence alignments, secondary structures, and multimeric engineering achievements. We also highlight the application of these aptamers as ligands for therapeutic agents and biosensor development. Overall, aptamers represent a compelling solution to the diagnostic and therapeutic challenges of COVID-19, and we hope this review propels further aptamer research for current and future pandemics.
Read more about the paper here: https://doi.org/10.1002/anse.202200012


Nucleic-Acid-Based Electrochemical Biosensors for Clinical Applications

We are excited to announce our recent review paper on the use of nucleic acids in electrochemical biosensors in collaboration with the Dr. Soleymani lab. Nucleic acids have unique structural motifs that allow them to bind non-nucleic acid targets (aptamers) and catalyze chemical reactions (DNAzymes), making them excellent candidates for use in biosensors. This review paper highlights the historical evolution of nucleic acids as probes in electrochemical biosensors and provides specific examples of their use in clinical settings such as infectious disease, cancer, and cardiovascular health. DNA, in particular, has proven to be an ideal biorecognition element and redox reporter probe due to its ability to be easily modified with various functional groups. We hope that our review will serve as a valuable resource for researchers in the field of biosensors and contribute to the development of new diagnostic tools for a wide range of diseases. Read more about it here: https://doi.org/10.1002/anie.202212496


A Universal Aptamer for SARS-CoV-2 Detection

We’re excited to share our latest work on SARS-CoV-2 where we expand on our previous publications and describe an aptamer class that binds all major variants of concern with high affinity. This is an important tool for the development of aptamer based COVID detection technologies that can be specific, sensitive and robust for the detection of current and possibly future variants. Read more about our work here. -Jim

Zhang Z, Li J, Gu J, Amini R, Stacey HD, Ang JC, White D, Filipe CDM, Mossman K, Miller MS, Salena BJ, Yamamura D, Sen P, Soleymani L, Brennan JD, Li Y. A Universal DNA Aptamer that Recognizes Spike Proteins of Diverse SARS-CoV-2 Variants of Concern. Chemistry. 2022 Feb 26:e202200524. doi: 10.1002/chem.202200524. Epub ahead of print. PMID: 35218097.

Aptamers from random sequence space: Accomplishments, gaps and future considerations

Aptamers are nucleic acids that are capable of recognizing target molecules. Over the past 30 years, thousands of aptamers have been discovered by scientists via in vitro selection technique. This review examined the range of targets as well as the affinity and specificity of ~1000 generated aptamers. By comparing the synthetic aptamers with natural riboswitches, protein-based recognition elements, a gap between synthetic aptamers and natural recognition elements was revealed.  A series of ideas for developing better aptamers were proposed to solve the real world problems. We hope these strategies can help aptamers remain high functionality in application environment. Happy reading 😊 – Shuwen Qian

Qian, S.; Chang, D.; He, S.; Li, Y. Aptamers from Random Sequence Space: Accomplishments, Gaps and Future Considerations. Analytica Chimica Acta 2022, 1196, 339511. https://doi.org/10.1016/j.aca.2022.339511

Applying our SARS-CoV-2 Aptamers for Diagnostics

Following up on our recent report of high-affinity DNA aptamers for SARS-CoV-2, we’ve been busy working with our collaborators in the Soleymani Lab and the Biointerfaces Institute to apply them on electrochemical sensors. Read our latest COVID19 paper at Pubmed to learn more about how we achieve high sensitivity detection of SARS-CoV-2 in unprocessed human saliva to pave the way for a rapid and sample diagnostic test.

Facile Synthesis of Pd-Ir Nanocubes for Biosensing

Take a quick look at our recent publication in Frontiers in Chemistry. In this paper, a simple and surfactant-free approach is presented to synthesize Pd-Ir nanocubes with atomic Ir shell thickness in an aqueous solution at room temperature. Biomolecules such as antibodies and nucleic acids have free access to the surface of Pd-Ir nanocubes. Applications of Pd-Ir nanocubes in immunoassays and aptamer-based biosensors are realized, exploiting the excellent peroxidase activity and fluorescence quenching ability of Pd-Ir nanocubes. Read more about our work at Pubmed. – Jiuxing

Li J, Li Y. Facile Synthesis of Pd-Ir Nanocubes for Biosensing. Front Chem. 2021 Nov 24;9:775220. doi: 10.3389/fchem.2021.775220. PMID: 34900937; PMCID: PMC8651546.

Welcome to Giulia Core

The Li Lab welcome our newest member, Giulia Core, who will be joining us as a visiting Ph.D. student from the University of Glasgow. She will be working on molecular diagnostic technologies.

DNA Aptamers for SARS-CoV-2

The Li Lab and our collaborators from across the McMaster community have published our first report on our novel aptamers for COVID19! The lab has refocused our efforts over the past year to address pressing COVID19 problems and we’re excited to finally be sharing our work. Read more about our work at Pubmed.

NSERC & L’Oréal-UNESCO Women in Science and IUPAC Young Chemist

Li Lab postdoctoral fellow Erin McConnell has been awarded the NSERC & L’Oréal-UNESCO Women in Science Supplement. Congratulations to Erin for her fantastic work as a scientist and as a role model for young scientists around the world.

Explore the following links to learn more about Erin’s work and the work of the other great researchers recently recognized.

Canadian Awarding ceremony of the L’Oréal-UNESCO For Women in Science fellowships

NSERC and L’Oréal-UNESCO For Women in Science Supplement

L’Oréal-UNESCO For Women in Science 2018: Erin McConnell

IUPAC Young Chemist


A DNAzyme Feedback Amplification Strategy for Biosensing

Take a look at this recent publication from the Li Lab in Angewandte Chemie International Edition. In this paper, we explore a novel signal amplification strategy termed DNAzyme feedback amplification (DFA). This method takes advantage of rolling circle amplification and RNA-cleaving DNAzymes for biosensing applications, with sensitivity improvements of 3-6 orders of magnitude when compared to conventional methods. -Suraj

Detection of DNA Amplicons of Polymerase Chain Reaction Using Litmus Test

Checkout this recent paper from the Li Lab in Scientific Reports, “Detection of DNA Amplicons of Polymerase Chain Reaction Using Litmus Test.” Here we report on a novel DNA detection method that combines the advantages of the polymerase chain reaction with the simplicity of a litmus test. The diagnostic capabilities of the platform is demonstrated using clinically validated stool samples from C.difficile infected patients. -Suraj



Funding for Legionella Biosensors Brings Research and Industry Together

Funding was recently announced to advance the Li lab’s research into rapid Legionella diagnostic technologies. Congratulations to our McMaster collaborators Dr. Carlos Filipe and Dr. John Brennan of the Biointerfaces Institute  and industry partners TGWT Clean Technologies Inc., Cytodiagnostics and Mold and Bacterial Consulting Labs. Read more about it on the McMaster News website.

Meet Sep (& his current focus)

SepI am currently in my 3rd year as a PhD student in the Li Lab, and I am ecstatic to be a part of our efforts to develop colorimetric assays for a wide range of biologically relevant targets. I am currently working on the development of diagnostic assays that will enable detection of important cancer biomarkers.


McMaster direct-entry PhD student ranked 6th in nationwide CIHR competition

Sepehr Manochehry, a PhD candidate in his 3rd year, earned the coveted CIHR doctoral scholarship this year. He was ranked 6th nationwide, putting him in the top one percentile among more than 700 other applicants. His success and the focus of his research was recently featured in a news magazine article. Read it to gain a better understanding of what motivates hard-working graduates students like Sepehr.  http://biochemrocks.freeflowdp.com/biochemrocks/2357984385961772?pg=23#pg23




A Busy Week of Holiday Festivities

The Li Lab came together to participate in the departmental ginger bread house contest, coming up with a 2 part winter wonderland gingerbread house and Eiffel tower. Congrats to us on winning 1st place! Check out the rest of the details at the BBS Facebook Page.

Christmas 2015 3

Christmas 2015 2

Everyone also came out to the annual Li Lab Christmas lunch.

Christmas 2015

Finally, our 2nd annual Secret Santa was also a huge success and a lot of fun!

Turning up the Volume on Target Detection

menglCheck out the Li Lab’s latest publication in Angewandte Chemie International Edition“Biosensing by Tandem Reactions of Structure Switching, Nucleolytic Digestion, and DNA Amplification of a DNA Assembly”. Postdoc Meng Liu has developed a novel, high sensitivity DNA based signal amplification technique using an isothermal DNA polymerase and structure switching DNA aptamers. This work brings DNA aptamer based detection technologies another step closer to convenient and cost effective point of care applications.


Hot off the Bench

Evolution of an Enzyme from a Noncatalytic Nucleic Acid Sequence

rachelgLife as we know it requires thousands of biological molecules, called enzymes, which carry out chemical reactions and allow life to exist. These molecules did not appear out of thin air – they evolved out of a mixture of the Earth’s first compounds, known as prebiotic soup. One theory for how life originated is known as the “RNA World” Hypothesis: ribonucleic acid (RNA), capable of both encoding information and performing enzymatic reactions, could have been the initiator of the origins of life, bridging the gap between life and non-life.

In this project, we used a sequence of DNA as a proxy for RNA in the origins of life. Wesubjected it to a process called in vitro selection, where we randomly introduced small variations in the sequence and then obliged the sequences to carry out a reaction. The sequences were filtered – only sequences able to perform the specific reaction were permitted to survive. These unique sequences were then subjected to cycles of this process – induction of small variations, and segregation of competent sequences. Using this method, we were able to take a sequence which was incapable of an enzyme-like reaction, and evolve it with minimal changes into a sequence adept at executing the reaction. This experiment allows us a tiny peep into how RNA molecules could have acquired function at the brink of the origin of life.

-Rachel Gysbers


Li Lab Runs Around the Bay!

Last Sunday March 29th, five members of the Li Lab ran Hamilton’s Around the Bay Road Race, the oldest race in North America. Kha, Shahrzad and Zohaib ran in the 5 km race, while Dingran and Rachel joined Fazmin from the CMCB in running the 30 km race. The event was exciting and these members of the lab were thrilled to finish and receive medals celebrating their accomplishments. They’re looking forward to surpassing their times in next year’s race!

Thesis in Three Minutes!

This year, the Li lab was proud to have three graduate students represent them at McMaster’s 3-minute thesis competition. On February 11th, Sepehr, Dingran and Rachel all presented their research to a non-specialist audience in less than three minutes. These three students made up three quarters of those representing the Biochemistry & Biomedical Sciences Department. Although none of them made it to the finals, they found it an interesting and engaging experience.