Engineering covalent organic frameworks with defect for high-performance immunosensor

A team for biosensor research led by Prof. Genxi Li from Nanjing University in Nanjing, China recently reported the engineered covalent organic frameworks with defect for high-performance immunosensor. The study introduced a defect-engineering strategy to tailor COFs for in situ horseradish peroxidase (HRP) encapsulation, enhancing catalytic activity. By incorporating monoaldehyde ligands, structural defects were precisely tuned to optimize HRP’s microenvironment and conformation. Defective HRP@COFs exhibited superior activity over pristine COFs, attributed to spatial confinement and enzyme conformation synergy. An immunosensor based on defective HRP@COFs achieved ultrasensitive detection of prostate-specific antigen (PSA) with high specificity, enabling clinical discrimination of prostate cancer (PCa).

The team published their study in Nano Research on December 25, 2025.

Enzyme-based immunosensors, which rely on antibody-antigen recognition and enzymatic signal transduction, are limited by enzyme instability and low catalytic efficiency for trace analyte detection. Although COFs immobilization improves stability, physical adsorption leads to enzyme leaching and mass transfer limitations from COFs shells reduce catalytic efficiency, posing challenges for biosensing applications. Recent studies demonstrate that regulating enzyme conformation through defect engineering, such as tuning enzyme-carrier interactions or incorporating functional ligands, can enhance catalytic performance, offering a potential strategy to develop high-performance immunosensors.

“The deliberate introduction of monoaldehyde ligands into COFs enables precise defect customization, which can modulate HRP's microenvironment and conformation to enhance catalytic performance,” said Prof. Li, corresponding author from the School of Life Sciences, Nanjing University.

The research team proposes a defect-engineering strategy to rationally design defective COFs for the in-situ encapsulation of HRP, improving its catalytic activity. By introducing monoaldehyde ligands into the COFs structure, precise defect customization is achieved, modulating the HRP microenvironment and conformation. The resulting defective HRP@COFs exhibit superior enzymatic activity, attributed to synergistic spatial confinement and optimized enzyme conformation. Based on the optimal defected-engineering system, the researchers have also developed a highly sensitive and specific immunosensor for PSA detection.

“The proposed sensor demonstrates a low detection limit and strong anti-interference capability, effectively distinguishing PCa patients from healthy controls in clinical serum samples,”Prof. Li stated.

Other contributors include Tianci Zhou, Ying Deng, Yu Sun, Keqing Ying, Dongmei Zhang and Xiafei Hu from the School of Life Sciences, Nanjing University in Nanjing, China; Jinlong Li from the Second Hospital of Nanjing, Nanjing University of Chinese Medicine in Nanjing, China.

This work was supported by the Nanjing Second Hospital talent lifting project (Grant No. RCZD23001), the Jiangsu Province traditional Chinese medicine science and technology development general program (Grant No. MS2023063), Medical Science and Technology Development Foundation, Nanjing Department of Health (Grant No. ZKX20033) and Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX25_0240).

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.