Fabrication of Biomolecule Microarrays for Cell Immobilization Using Automated Microcontact Printing

Advancing High-Throughput Cellular Atomic Force Microscopy with Automation and Artificial Intelligence

Atomic force microscopy (AFM) has reached a significant level of maturity in biology, demonstrated by the diversity of modes for obtaining not only topographical images but also insightful mechanical and adhesion data by performing force measurements on delicate samples with a controlled environment (e.g., liquid, temperature, pH). Numerous studies have applied AFM to describe biological phenomena at the molecular and cellular scales, and even on tissues. Despite these advances, AFM is not established as a diagnostic tool in the biomedical field. This article describes the reasons for this gap, focusing on one of the main weaknesses of bio-AFM: its low data throughput. We review current efforts to improve the automation of AFM measurements in particular on living cells, as well as the developments in automating data analysis. For the latter, artificial intelligence (AI) is progressively employed to classify data to distinguish healthy and diseased cells or tissues. Finally, we propose a roadmap to foster the application of bio-AFM into medical diagnostics.

Advancing cellular transfer printing: achieving bioadhesion-free deposition via vibration microstreaming

Cell transfer printing plays an essential role in biomedical research and clinical diagnostics. Traditional bioadhesion-based methods often necessitate complex surface modifications and offer limited control over the quantity of transferred cells. There is a critical need for a modification-free, non-labeling, and high-throughput cell transfer printing technique. In this study, an adhesion-free cellular transfer printing method based on vibration-induced microstreaming is introduced. By adjusting the volume of the microcavity, the number of cells transferred per microtiter well can be realized to the level of a single cell. Additionally, it allows for precise control of large-scale cellular spatial distribution, leading to the formation of biomimetic patterns. Moreover, the demonstrated biocompatibility and high throughput of this cell transfer printing method highlight its potential utility. The correspondence of the transferred cell amount to the vibration and frequencies allows the system to exhibit excellent tunability of the transferred cell amount and pattern. This bioadhesion-free cell transfer printing method holds promise for advancing cell manipulation in biomedical research and analysis.

Advances in Single-Cell Printing

Single-cell analysis is becoming an indispensable tool in modern biological and medical research. Single-cell isolation is the key step for single-cell analysis. Single-cell printing shows several distinct advantages among the single-cell isolation techniques, such as precise deposition, high encapsulation efficiency, and easy recovery. Therefore, recent developments in single-cell printing have attracted extensive attention. We review herein the recently developed bioprinting strategies with single-cell resolution, with a special focus on inkjet-like single-cell printing. First, we discuss the common cell printing strategies and introduce several typical and advanced printing strategies. Then, we introduce several typical applications based on single-cell printing, from single-cell array screening and mass spectrometry-based single-cell analysis to three-dimensional tissue formation. In the last part, we discuss the pros and cons of the single-cell strategies and provide a brief outlook for single-cell printing.

Antibody Micropatterned Lubricant-Infused Biosensors Enable Sub-Picogram Immunofluorescence Detection of Interleukin 6 in Human Whole Plasma

Recent studies have shown a correlation between elevated interleukin 6 (IL-6) concentrations and the risk of respiratory failure in COVID-19 patients. Therefore, detection of IL-6 at low concentrations permits early diagnosis of worst-case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL-6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL^-1 . The sensitivity of the developed lubricant-infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL-6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy-based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant-infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.

Single-cell patterning technology for biological applications

Single-cell patterning technology has revealed significant contributions of single cells to conduct basic and applied biological studies in vitro such as the understanding of basic cell functions, neuronal network formation, and drug screening. Unlike traditional population-based cell patterning approaches, single-cell patterning is an effective technology of fully understanding cell heterogeneity by precisely controlling the positions of individual cells. Therefore, much attention is currently being paid to this technology, leading to the development of various micro-nanofabrication methodologies that have been applied to locate cells at the single-cell level. In recent years, various methods have been continuously improved and innovated on the basis of existing ones, overcoming the deficiencies and promoting the progress in biomedicine. In particular, microfluidics with the advantages of high throughput, small sample volume, and the ability to combine with other technologies has a wide range of applications in single-cell analysis. Here, we present an overview of the recent advances in single-cell patterning technology, with a special focus on current physical and physicochemical methods including stencil patterning, trap- and droplet-based microfluidics, and chemical modification on surfaces via photolithography, microcontact printing, and scanning probe lithography. Meanwhile, the methods applied to biological studies and the development trends of single-cell patterning technology in biological applications are also described.