In the rapidly advancing field of structural biology, obtaining high-resolution insights into the complex architecture of biological molecules is paramount for understanding fundamental mechanisms and driving drug discovery. Single Particle Analysis (SPA), a powerful application of Cryo-Electron Microscopy (Cryo-EM), has revolutionized our ability to determine the three-dimensional structures of challenging biological samples. This technique enables researchers to visualize macromolecules, viruses, and complexes in a near-native state, providing crucial structural information that is often unattainable through traditional methods like X-ray crystallography, especially for molecules that are difficult to crystallize.

Single Particle Analysis (SPA) fundamentally involves taking numerous two-dimensional images of purified biological particles frozen in a thin layer of vitreous ice. These images, representing different orientations of the same molecule, are then computationally processed and reconstructed to generate a high-resolution three-dimensional structural model. The power of SPA lies in its ability to reveal the structures of diverse biological entities, including proteins (like membrane proteins, enzymes, and ribosomal complexes), nucleic acids (DNA and RNA structures), protein-nucleic acid complexes (such as transcription complexes), and viral particles. Beyond determining static structures, SPA can also capture multiple conformational states of a molecule, offering insights into dynamic processes. It typically requires only small amounts of sample and can be used to determine the structure of heterogeneous protein complexes.

ShuimuBio stands as a leading platform in the realm of Single Particle Cryo-EM & Analysis, providing comprehensive, high-resolution structural determination services. Founded in 2017 at Tsinghua University, ShuimuBio was established as Asia's first commercial platform offering Cryo-EM structure analysis services. The core team comprises experts from life sciences, computation, IT, and the pharmaceutical industry, leveraging deep research and technological foundations from Tsinghua University's structural biology discipline. This expertise ensures advanced and reliable experimental procedures and data analysis workflows.

ShuimuBio's Single Particle Analysis solution is presented as a "one-stop" service. This comprehensive approach aims to streamline the structural determination process, saving time and costs for clients. The typical workflow encompasses project consultation and communication, feasibility evaluation, plan determination, contract and payment, followed by experimental stages including protein expression and purification, negative stain characterization, sample freezing and data collection, two-dimensional particle picking, three-dimensional structure reconstruction, model refinement, and finally, data delivery. This integrated service addresses challenges from gene sequence all the way to high-precision 3D protein structures.

A key strength of ShuimuBio is its advanced Cryo-EM facilities. The company boasts the world's largest commercial Cryo-EM platform, equipped with high-end 300 KV microscopes. The platform includes 8 such microscopes (2 in Beijing and 6 in Hangzhou), which are at the core of their commercial structure analysis services. These microscopes are designed specifically for high-quality structure resolution and are equipped with high-performance detectors, energy filters, aberration correctors, and phase plates to maximize imaging quality. Rigorous daily maintenance and inspection ensure that the equipment operates in its optimal state, achieving high annual availability (over 330 days per year per microscope, with >97% uptime).

Accompanying the cutting-edge hardware is an elite team of PhD-level scientists from top institutions, specializing in structural biology, protein science, and computational biology. Their extensive experience is evident in the platform's track record. ShuimuBio has successfully completed over 400 Cryo-EM projects, including more than 300 Single Particle projects, and has resolved over 150 protein structures. They have achieved impressive resolution, with a best resolution of 1.8 Å and a breakthrough resolution of 1.4 Å. They have also successfully determined the structure of relatively small proteins, with the minimum molecular weight resolved being 51 kDa.

To further enhance the efficiency and accuracy of Cryo-EM Single Particle Analysis, ShuimuBio has independently developed an AI-driven platform, featuring the SMART software series. This software leverages artificial intelligence to optimize the data analysis process, reducing machine runtime and required data volume, and improving the overall efficiency of Cryo-EM data analysis. Another AI-powered tool, NanoSMART, is specifically designed for cryo-characterization, enabling automatic recognition of nanoparticle features from images, optimizing recognition by enhancing low-quality images, and providing detailed reports. NanoSMART is particularly useful for analyzing lipid nanoparticles (LNP), liposomes, AAV, and other viral vectors, assessing parameters like size distribution, circularity, lamellarity, fullness/emptiness, and integrity.

ShuimuBio also addresses common challenges in Cryo-EM sample preparation for Single Particle Analysis. Traditional support grids can suffer from issues such as air-liquid interface absorption, severe preferred orientation, high sample concentration thresholds (>1 μM), significant background noise, and difficulty reconstructing small macromolecule structures. To overcome these limitations, ShuimuBio has developed the GraFuture™ series of graphene grid support films. These grids provide a potential solution for the preferred orientation problem and are suitable for challenging applications involving proteins with small molecular weight, low concentration, strong background noise, or air-liquid interface damage. The series includes both GraFuture™ GO (graphene oxide) and GraFuture™ RGO (reduced graphene oxide).

Beyond the core Single Particle Analysis service, ShuimuBio offers 24-hour Cryo-EM machine time service. This service provides convenient and efficient access to their 300kV Cryo-EM platforms in Beijing and Hangzhou for data collection. They offer a 24-hour response for booking requests and have established channels for urgent bookings. The service integrates the entire workflow, including supporting equipment like Vitrobot and surface plasma processors. Clients can choose between online remote hole picking or utilizing the expertise of Shuimu scientists for hole selection, with experienced technical personnel providing real-time support during data collection. Strict platform maintenance ensures high efficiency and quality data collection, providing stable and reliable service.

Cryo-EM Single Particle Analysis has a wide range of applications across various fields of life science and drug development:

· Structural Biology Research: Determining the high-resolution three-dimensional structures of diverse biomacromolecules such as membrane proteins (e.g., GPCRs like GPR75, ion channels like TRPML1, transporters), enzymes (e.g., CYP51, PolQ), ribosomes, DNA and RNA, and complex assemblies like transcription complexes or viral capsid-RNA complexes. This fundamental information is critical for understanding function.

· Vaccine Development: Cryo-EM plays a vital role by enabling the resolution of virus structures at near-atomic resolution, which helps researchers understand viral invasion mechanisms and informs vaccine design. Examples include studies on SARS-CoV-2 spike protein interactions with ACE2, influenza attenuated live vaccine strategies, and measles virus neutralization by antibodies. The technology is also used for vaccine quality control, checking morphology, particle size, integrity, and aggregation. Furthermore, it facilitates research into the interaction between antibodies and vaccine antigens to optimize immunogenicity. Its rapid structure resolution capability is also crucial for addressing viral variation, allowing scientists to quickly analyze new variants and adjust vaccine design strategies.

· Antibody Drug Discovery: Cryo-EM provides high-resolution structural information for understanding antibody-antigen recognition mechanisms and binding sites. This is essential for designing more effective antibody drugs, such as visualizing how antibodies bind to viral surface proteins to block infection. The technology is also used to study the mechanism of action of antibody drugs, including how they interact with targets and influence signaling pathways. Structural analysis through Cryo-EM helps in the optimization and design of antibody drugs, revealing binding dynamics and conformational changes to create antibodies with higher affinity and specificity. It is particularly valuable for resolving the structures of membrane protein targets, which are common in antibody drug development. The high speed and resolution of Cryo-EM also help accelerate the antibody drug development process by providing rapid structural insights for design optimization.

· Small Molecule Drug Discovery: Cryo-EM enables the resolution of high-resolution structures of drug targets, such as membrane proteins (e.g., GPCRs) and enzymes. This structural information helps researchers understand the binding details of small molecule ligands, providing a basis for designing highly selective and effective drugs. The technology is used to study the mechanism of interaction between small molecules and their targets, revealing how drugs activate or inhibit receptors and modulate signaling pathways. Cryo-EM is also showing potential in Fragment-Based Drug Discovery (FBDD), providing details on fragment binding to protein targets to help screen and optimize drug candidates. Similar to antibody drugs, Cryo-EM accelerates small molecule drug R&D by quickly providing detailed structural information for design optimization. It has unique advantages in studying biased ligands that selectively target specific pathways mediated by GPCRs.

· PROTAC Research: Cryo-EM provides crucial structural biology insights into the application of PROTAC molecules.

· Nanoparticle and Viral Vector Characterization: As mentioned, cryo-characterization services using tools like NanoSMART are available for analyzing the structure and characteristics of lipid nanoparticles (LNP), liposomes, and AAV vectors.

ShuimuBio's expertise and technology have contributed to significant scientific advancements, with numerous research outcomes from projects utilizing their platform published in international top-tier journals. These publications cover structural studies of a wide range of biological targets resolved at atomic resolution, including ion channels, GPCRs, antibody-antigen complexes, and spliceosomes, among others. Specific examples include structures of human NMDA receptors, histamine H1 receptor complexes, bradykinin receptors, and various SARS-CoV-2 antibody complexes. Their publication record highlights successful collaborations and the high quality of data generated.

To support the entire workflow for structural determination projects, ShuimuBio also offers comprehensive protein preparation and analysis services. This includes access to various protein expression systems (bacterial, mammalian, insect, cell-free), purification technologies (affinity, ion exchange, gel filtration, RP-HPLC), and characterization methods (SDS-PAGE, Western blot, mass spectrometry, thermal stability, solubility, SPR, BLI, ELISA). They possess deep experience specifically in the challenging field of membrane protein production and purification, offering flexible collaboration models and strict quality control, often informed by Cryo-EM analysis. Additionally, they offer MicroED solutions for resolving high-resolution structures from micro/nano crystals of small molecules, peptides, and proteins, and One-stop Crystal Structure Analysis using X-ray crystallography for samples suitable for crystallization. Negative Stain services are available for initial, low-resolution assessments of sample quality, uniformity, and morphology before proceeding to Cryo-EM Single Particle Analysis.

In summary, ShuimuBio is a global leader in providing High-Resolution Single Particle Cryo-EM & Analysis Solutions. With state-of-the-art 300kV Cryo-EM facilities, an expert scientific team, a proven track record of high-resolution structure determination, innovative AI platforms like SMART and NanoSMART, and specialized solutions like GraFuture™ grids for challenging samples, they offer comprehensive, one-stop services from protein preparation to final 3D structure resolution. Their services are critical for accelerating research and development in structural biology, drug discovery (including antibody and small molecule drugs), and vaccine development.

To learn more about ShuimuBio's services in Single Particle Analysis, Cryo-EM, protein science, and other structural biology solutions, and to explore how their expertise can support your research projects, please visit https://shuimubio.com/.