Hepatocellular carcinoma (HCC) accounts for more than 90% of primary liver cancer and remains a worldwide health problem due to its aggressive and lethal nature. Transarterial chemoembolization (TACE) is the first-line treatment for unresectable HCC. This treatment involves the embolization of tumor vessels and the delivery of high-concentration chemotherapy drugs, which are locally released into the tumor tissues to promote tumor necrosis. However, the therapeutic effect of this method has always been controversial. Therefore, designing an ideal embolization model to evaluate the pharmacokinetics inside the tumor site and accurately evaluate the therapeutic effects of clinically relevant embolization agents is of great significance. Assistant Professor Qiongyu Guo’s team from the Department of Biomedical Engineering and Assistant Professor Xiaoying Tang’s team from the Department of Electronic and Electrical Engineering at the Southern University of Science and Technology (SUSTech) have recently collaborated on the publication of a visualized 3D tumor-mimicking chemoembolization model. The model, which combines deep learning and graph analysis methods, has made significant progress in the construction of an ex vivo organ-structured evaluation platform for liver cancer chemoembolization treatment. Their research results, entitled “A 3D Tumor-Mimicking in Vitro Drug Release Model of Locoregional Chemoembolization Using Deep Learning Based Quantitative Analyses,” have been published in Advanced Science. Figure 1. Schematic diagram of the 3D embolization model based on deep learning. Prof. Qiongyu Guo’s and Prof. Xiaoying Tang’s teams collaborated to design a 3D tumor-mimicking drug release model through utilizing decellularized liver organ as a drug-testing platform (Figure 1). The model contains three key features that affect drug release in vivo: a complex vascular system, a drug-diffusible electronegative extracellular matrix, and controllable drug depletion. This drug release model, combined with deep learning-based computational analyses for the first time, permits quantitative evaluation of all important parameters associated with locoregional drug release. The U-shaped segmentation network based on attention mechanism and adversarial training can achieve accurate segmentation of the embolized vascular region with few annotated samples. A series of image processing and graph analysis algorithms were combined to achieve an accurate and automatic quantitative statistical analysis of drug loss. To further verify the feasibility and accuracy of the model, the study quantitatively analyzed the endovascular embolization distribution, intravascular drug retention, and extravascular drug diffusion, establishing an in vivo-in vitro correlation with in-human results up to 80d. Using the established 3D tumor-mimicking model, the in vitro chemoembolization efficacy of three different formulations of doxorubicin solution was systematically evaluated (Figure 2). The researchers used image processing algorithms to extract the skeleton of the segmented embolized vessels and constructed a custom multi-level tree. Subsequently, quantitative analysis and statistical comparison were performed at different tree levels, allowing for a clear depiction of the differences in embolization depth and changes in residual drugs within blood vessels for the three formulations over 80 days. Figure 2 Vessel topological analyses. Skeleton extraction and classification of drug-containing vessels of three drug formulations, i.e., DOX Ctrl, EO-DOX, and DEB, tested in the DLM model over 80 d. DOX: doxorubicin solution; EO-DOX: emulsion of ethiodized oil and doxorubicin solution; DEB: drug eluting bead. The local drug concentration within tumors is an important factor in determining their therapeutic efficacy. Taking advantage of the visualization capabilities of the 3D model and the strong self-fluorescence of doxorubicin at low concentrations, the researchers determined the extracellular drug diffusion depth as compared to the drug diffusion behavior observed in in vivo experiments. They found that the drug diffusion depth in this 3D model exhibited great linearity with the in-human results, validating the effectiveness of the embolic chemotherapy model for in vivo–in vitro consistency evaluation. This has important guiding significance for the development of new drug formulations and evaluation of embolic chemotherapy efficacy in clinical practice (Figure 3). Figure 3 Extravascular drug diffusion of drug eluting beads in DLM model and IVIVC. Dr. Xiaoya Liu, a postdoctoral fellow from the Department of Biomedical Engineering at SUSTech, and Xueying Wang, a master’s student from the Department of Electronic and Electrical Engineering at SUSTech, are the first authors of this paper. Asst. Prof. Qiongyu Guo and Asst. Prof. Xiaoying Tang are the corresponding authors. SUSTech is the corresponding institution of the paper. Other collaborating authors included master’s students Yucheng Luo, Meijuan Wang, and Xiaoyu Han, all from SUSTech. This work was supported by the National Natural Science Foundation of China (NSFC), Guangdong Innovative and Entrepreneurial Research Team Program, Science, Technology and Innovation Commission of Shenzhen Municipality, and SUSTech. Paper link: https://onlinelibrary.wiley.com/doi/10.1002/advs.202206195?af=R
While fluorescence microscopy with high contrast and super-resolution has revolutionized structural cell biology studies, high-throughput imaging with rich information content has enabled quantitative biology research. An emerging trend is developing high-throughput super-resolution imaging techniques for high-content screening. However, field-dependent aberrations restrict the field of view (FOV) of super-resolution imaging to only tens of micrometers. Associate Professor Yiming Li from the Advanced Microscopy Imaging Laboratory in the Department of Biomedical Engineering at the Southern University of Science and Technology (SUSTech) led a team to develop a deep learning algorithm framework to address the field-dependent aberrations and bypass the bottleneck for large FOV imaging. Their research results, entitled “Field-dependent deep learning enables high-throughput whole-cell 3D super-resolution imaging,” has been published in Nature Methods. The researchers developed a deep learning method for precise localization of spatially variant point emitters (FD-DeepLoc) over a large FOV covering the full chip of a modern sCMOS camera. Using a graphic processing unit (GPU) based vectorial PSF fitter, they can fast and accurately model the spatially variant point spread function (PSF) of a high numerical aperture (NA) objective in the entire FOV. Combined with deformable mirror-based optimal PSF engineering, they demonstrate high-accuracy 3D SMLM over a volume of ~180 × 180 × 5 μm3, allowing people to image mitochondria and nuclear pore complexes in entire cells in a single imaging cycle without hardware scanning – a 100-fold increase in throughput compared to the state-of-the-art. This work provides new technical ideas and perspectives for the field of super-resolution microscopy. It also has important theoretical and practical value for the study of nanoscale biological structures in complete cell populations or tissues. Figure 1. Large FOV imaging of cellular nuclear pores Shuang Fu and Wei Shi, doctoral students at SUSTech, are the co-first authors of this paper. Assoc. Prof. Yiming Li is the corresponding author, and SUSTech is the first affiliation. This work was supported by the Key Technology Research and Development Program of Shandong, Science, Technology and Innovation Commission of Shenzhen Municipality, and Start-Up Fund from SUSTech. Paper link: https://www.nature.com/articles/s41592-023-01775-5
The project “Flexible Electronic Materials for Controlled Drug Release and Tissue Regeneration Devices” led by Prof. Zhi LUO, Associate Professor of the Department of Biomedical Engineering, was approved by the Ministry of Science and Technology of China. Born in 1991, Prof. LUO is the youngest chief scientist of the National Key R&D Program of SUSTech.
In nature, the transmission and processing of information, as well as the energy conversation and storage, are often mediated and regulated using ions and fluids transportation at small scales (e.g., nanopores). It can be said that the language of intelligent life is “ions”, and the language of artificial intelligence is “electrons”. To realize seamless communications between intelligent life and artificial intelligence, building an artificial intelligence system with “ions” as language is necessary. We should fabricate artificial nanopores on the nanoscale to realize controllable ions transport, which is common in the biological nanopore. On a microscale, it is significant to build an artificial neuron to replicate the generation of the action potential by ions transport. On a macroscale, the construction of a bioinspired neural network is necessary to realize ionic signal transmission and information storage. Associate Professor Kai Xiao’s research team from the Department of Biomedical Engineering at the Southern University of Science and Technology (SUSTech) has made progress on this topic by achieving a series of advances in the field of Bio-inspired Multiscale Ionic Neuromorphic Devices. Their subsequent papers have been published in top international journals such as Nature Communications, CCS Chemistry, Advanced Science, and ACS Nano. Ionic diode property widely exists in the biological nanopore of intelligent living organisms. To control ions transport unidirectional, cells living organisms can realize a series of physiological activities such as the generation of action potentials and the control of cell osmotic pressure. To realize ionic diode properties in vitro, Prof. Xiao’s team fabricated a carbon-based nanofluid with multiple scales and realized ionic diode properties with an ionic rectification ratio (on-off ratio) of more than 10,000. This work breaks the existing diode mode of “silicon materials + electrons”, and builds a life-like new diode model of “carbon materials + ions”. This lays a good foundation for the construction of ion transport-based logic circuits and derives ion transport-based transistors and neurons. The related research results, entitled “Unidirectional ion transport in nanoporous carbon membranes with a hierarchical pore architecture,” were published in Nature Communications. Figure 1. Carbon-based nanofluids with multiple scales and its ionic diode properties An ion pump is a unique function of intelligent life. It can realize the reverse concentration gradient transport of ions by consuming external energy. This progress is important for many physiological activities, such as photosynthesis, ATP synthesis, and action potential generation. How to construct a biomimetic ion pump can lay a good foundation for the technological breakthrough of various devices such as ion transport-based photoelectric energy conversion and neural signal regulation. In their earlier research (Nat. Commun. 2019, 10, 74; Natl. Sci. Rev. 2021, 8, nwaa231.), the researchers realized a series of biomimetic ion pump functions and applications by constructing a nanofluidic system based on semiconductor materials. Most recently, they proposed that biomimetic ion pumps can be constructed by introducing asymmetric elements into a nanofluids system. For example, for the widely studied biomimetic light-driven ion pumps, light-driven ion pump properties can be realized by the asymmetric photoelectric effect, photothermal effect, and photochemical reaction, respectively This study, entitled “Light-Driven Ion Transport in Nanofluidic Devices: Photochemical, Photoelectric, and Photothermal Effects,” was published in CCS Chemistry. Figure 2. Compared to electrons, ions have many unique advantages in designing energy and information devices. For example, various valencies, different sizes, and diverse polarizabilities. These characterizations enable all energy and information processors constructed by electrons to be redefined by ions. In recent years, with the development of artificial intelligence (AI) and a deeper understanding of biological intelligence, researchers have found that devices based on electron transport have significant limitations in the process of realizing human-computer interaction. By learning from nature, constructing ions transport-based energy and sensor devices can lay a good foundation for developing the next-generation brain-computer interface and realizing seamless human-computer interaction. This research topic involves interdisciplinary fields such as chemistry, materials, devices, and biology. Prof. Xiao’s research group was invited to publish a series of reviews and perspectives on how to construct nanoionic devices to realize the functions that nanoelectronic devices cannot satisfy. These reviews, entitled “Nanoionics from Biological to Artificial Systems: An Alternative Beyond Nanoelectronics” and “Solid-State Iontronic Devices: Mechanisms and Applications,” were published in Advanced Science and Advanced Materials Technologies, respectively. They pointed out that ions can realize many of the functions that nanoelectronics can achieve. By learning from intelligent life, nanoionics devices also can realize some functions that nanoelectronics cannot. Meanwhile, these perspective articles analyze and compare the advantages and disadvantages of various devices based on ions and electrons. Based on ion transport, they predict that biomimetic nanoionic devices will be another research hotspot following nanoelectronic devices. Dr. Jianrui Zhang, Dr. Tianming Li, Ms. Tingting Mei, and Ms. Hongjie Zhang are the first authors of the above papers and reviews. Assoc. Prof. Kai Xiao is the corresponding author, while SUSTech is the first affiliation. This work was supported by the National Key Research of China. Paper and related links (In order of appearance above): Nature Communications: https://www.nature.com/articles/s41467-021-24947-3 CCS Chemistry: https://www.chinesechemsoc.org/doi/full/10.31635/ccschem.021.202101297 Advanced Science: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202200534 Advanced Materials Technologies: https://onlinelibrary.wiley.com/doi/10.1002/admt.202200205 Prof. Kai Xiao’s group webpage: http://www.xiaokai-group.cn/
A team of students from the Southern University of Science and Technology (SUSTech) recently won the Gold Award and the Best Website Award in China’s first synthetic biology innovation competition, SynBio Challenges 2022. The competition was sponsored by the Synthetic Biology Branch of the Chinese Society of Bioengineering, which aims to provide a platform for young students to communicate, learn, innovate, create, and cultivate their knowledge in synthetic biology, life sciences, and interdisciplinary disciplines. Twenty-seven teams from 21 universities and colleges across the country participated in SynBio Challenges 2022, and more than 2.2 million people viewed the event online. The SUSTech team, titled “SUSTech_Shenzhen_HCL”, was led by Prof. Ho Chun Loong from the Department of Biomedical Engineering as the Principal Investigator, Jun CHEN and Xinyi CHEN as the instructors, and Liqing YU, Songlin SHI, and Yehan WANG as the team leaders. In addition, 14 members from different majors, including Yingxuan GONG, Xianxian WANG, Yijie WANG, Siqi MEN, Hongqiu LEI, Jiayi LIU, Nanfei JIANG, and Xuancheng MO, formed the multidisciplinary team. Cholera is an acute diarrheal illness caused by infection of the intestine with Vibrio cholerae bacteria, which can cause dehydration and death in severe cases. The illness is associated with dysregulation of the gut microbiota, so modulation of the gut microbiota could be a treatment for cholera. Through genetic engineering technology, the SUSTech_Shenzhen_HCL team used Lactobacillus and Escherichia coli (E. coli) bacteria as carriers. They developed a probiotic system that can prevent and treat through the group effect between bacteria. As a result, the team won the Gold Award and the Best Website Award.
On April 22-23, 2022, the World Association for Chinese Biomedical Engineers (WACBE) held its 10th World Congress on Bioengineering. The virtual event was hosted by the Department of Biomedical Engineering (BME) at the Southern University of Science and Technology (SUSTech). Many experts and scholars presented plenary and keynote reports during the congress, which attracted many young scholars from different disciplinary and research backgrounds to participate in the event. The conference promotes the exchange of the latest research results in the field of biomedical engineering and enhances the intersection and integration of related disciplines. The WACBE World Congress on Bioengineering is an annual event that focuses on biomedical engineering approaches that drive innovative technologies and foster solutions. The congress attracts about 400 delegates from all over the world, including academic researchers, industry leaders, medical experts, and trainees.
Yekkuni L. BALACHANDRAN | 22/12/2021 Controlling the spread of the human immunodeficiency (HIV) virus might be the only feasible route for completely avoiding the intractable disease. However, crucial immunities are still difficult to be sufficiently triggered by vaccines alone, which greatly limits its practical application. Researchers from the Microfluidic-Biomaterials Lab at the Southern University of Science and Technology (SUSTech) have developed a two-dimensional nano-adjuvant comprising of rare-earth elements that improve the immunities generated by vaccines (HIV DNA vaccine in this case). The research article, titled “Two-dimensional nanosheets as immunoregulator improve HIV vaccine efficacy,” was published in Chemical Sciences, a scientific journal covering all aspects of chemistry. Introducing applicable immunoregulatory building blocks to endow planar materials with inherent immunoregulatory characteristics is a strenuous task. Some rare earths or rare-earth based complexes, because of their inherent immunoregulatory capability, can regulate the behavior of macrophages (antigen-representing cells) and immunity. Considering that multiple types of rare earths have immunoregulatory effects on the functions or behaviors of immune effector cells, selecting rare earths rationally is a core question for the design of immunoregulatory nanomaterials. Two rare earths, erbium (Er) and dysprosium (Dy), can activate macrophages and improve phagocytosis capability and bioactivity for the increased presentation of antigens. The heterogeneity of two-dimensional nanosheets (2D NSs) comprehensively regulates immune functions of both Er (ROS-based mechanism) and Dy (NO-based mechanism), in comparison with either Er- or Dy-alone 2D NSs. Because of their planar morphology, these 2D NSs target the mice lymph nodes without the use of any lymph node targeting functional molecules. Considering lymph nodes are a critical type of immunological tissue for mediating immune responses, the lymph node targeting capability of nanosheets effectively improve the efficacy of vaccines. Figure 1. Characterization of rare-earth 2D NSs. In regulating DNA vaccine-triggered immune responses, the 2D NSs simultaneously improve both humoral and cellular immune responses, compared to most other reported immunoregulators, which can only enhance either humoral or cellular responses. 2D NSs significantly improve the HIV-specific humoral response of IgG and the four subclasses (IgG1, IgG2a, IgG2b, and IgG3). Furthermore, the 2D NSs can boost the enhancement of cytotoxic T lymphocytes to produce HIV-specific IFN-γ to neutralize HIV-infected cells. The balanced enhancement of HIV-specific humoral and cellular immune responses regulated by 2D NSs gives an unparalleled advantage for realizing the neutralization (mediated by humoral response) and cytotoxicity (cellular response) against HIV. Figure 2. 2D NSs regulating HIV DNA vaccine-triggered immune responses 2D NSs-regulated HIV vaccine triggers six critical genes associated with various immunoregulation-related networks. The three natural killer cell lectin-like receptor subfamily genes Klrk1, Klrd1, and Klrc1, are triggered by nanosheets, which can effectively enhance the presentation of antigens. The 2D NSs induce the upregulation of the genes Ccr2 and Serpinb9 to regulate cytokine production. The 2D NSs are found to significantly up-regulate the expression of Msr1, a critical gene that activates the macrophages. The 2D NSs influences the immunoregulation-related network involving the activation of immune cells, antigen presentation, and the production of immune effectors to facilitate the HIV DNA vaccine to trigger stronger immune responses. Figure 3. Transcriptome profiling of 2D NSs improving HIV DNA vaccine In summary, the realization of the concept of 2D NSs immunoregulator dramatically broadens the choices to optimize the vaccination of infectious diseases, tumor immunotherapy, and other immune-based preventive treatment and therapy. The Microfluidic-Biomaterials Lab at SUSTech is the corresponding author of this paper. This work was supported by the National Natural Science Foundation of China (NSFC), the National Key R&D Program of China, the Chinese Academy of Sciences, Tencent Foundation through the XPLORER PRIZE, the Shenzhen Key Laboratory of Smart Healthcare Engineering, the Leading Medical Talents Program of Health Commission of Yunnan Province, the Young and Middle-Aged Academic and Technical Leaders Program of Yunnan Province, and the Basic Research Program of Yunnan Province. Paper link: https://pubs.rsc.org/en/content/articlelanding/2022/SC/D1SC04044H
Recently, scientists of the Microfluidic-Biomaterials Lab at the Southern University of Science and Technology (SUSTech) received the Chinese Scientists with Cell Press Best Paper Award 2020. Their paper, titled “Electronic Blood Vessel,” was published in Matter, a journal under the Cell Press publishing organization that covers the field of materials science. The team from SUSTech developed an electronic blood vessel by using poly(L-lactide-co-ε-caprolactone) (PLC) which encapsulates liquid metal to make a flexible and biodegradable circuit. The electronic blood vessels could integrate flexible electrons with three layers of blood vessel cells to imitate and surpass natural blood vessels. It can effectively promote cell proliferation and migration in the wound healing model through electrical stimulation. It can controllably deliver genes to specific parts of the blood vessel through electro-transfection. Through a 3-month in vivo study of the rabbit carotid artery replacement model, the authors evaluated the electronic blood vessel’s efficacy and biological safety in the vascular system. They confirmed its patency through ultrasound imaging and angiography. The research paves the way for the integration of flexible, degradable bioelectronics into the vascular system, which can be used as a platform for further treatments, such as gene therapy, electrical stimulation, and electronically controlled drug release. In the future, the electronic blood vessel can be integrated with other electronic components and devices to achieve diagnostic and therapeutic functions. This will enhance significantly personalized medical functions by establishing a direct connection in the blood vessel tissue-machine interface. Cell Press is an internationally renowned academic publishing organization. Since 2015, it has looked at Chinese papers published in its journals and promotes the scientific research achievements of Chinese scientists in life sciences, materials science, and interdisciplinary science. Paper link: https://www.sciencedirect.com/science/article/pii/S2590238520304938
Recently, a research team led by Professor Changfeng Wu from the Department of Biomedical Engineering at the Southern University of Science and Technology (SUSTech) developed a series of highly bright polymer dots probes. Through the functionalization of polymer dots probes and application in expansion microscopy, fine subcellular structures with a resolution of ≈ 30 nm can be resolved on a conventional fluorescent microscope. Their research, entitled “Expansion Microscopy with Multifunctional Polymer Dots,” was published in Advanced Materials, a top journal in the field of materials science. Super-resolution optical imaging won the 2014 Nobel Prize in Chemistry for its ability to provide resolution below the diffraction limit. The current super-resolution technology mainly contains two categories, one of which relies on patterned illumination modulation and the other one based on single-molecule positioning. Expansion microscopy uses a completely different strategy that physically enlarges the samples to allow clear distinction of adjacent molecules that are originally within the diffraction limit. This method does not rely on a complex imaging system, and nanoscale resolution can be achieved on a common confocal microscope. However, the fluorescence brightness attenuation caused by chemical quenching and density dilution during sample preparation has long been a challenge for further applications. Changfeng Wu’s research group developed multifunctional polymer dots for application in multicolor expansion microscopy to address this issue. The fluorescence intensity of Pdots in ExM was up to 6 times higher than those achieved using commercially available Alexa dyes. The impressive brightness of the Pdots facilitated multicolor ExM, thereby enabling a variety of subcellular structures, such as mitochondria, clathrin-coated pits, and neuron synapses to be visualized on traditional fluorescent microscopes (Figure 1a-c). Furthermore, the research group combined polymer dots probes, expansion microscopy, and super-resolution optical fluctuation microscopy to achieve ultrahigh-resolution imaging of subcellular structures on a conventional wide-field microscope. As a result, this reflected the actual size of microtubules and the hollow membrane structure of mitochondria (Figure 1d-j). These findings highlight the immense potential of highly bright polymer dots for biological imaging. Figure 1. Three-dimensional super-resolution expansion and optical fluctuation imaging of subcellular structures The immunofluorescence staining of samples is tedious and time-consuming. To improve the efficiency of the project, Zhihe Liu, a postdoctoral fellow in the research group, designed an automatic cell immunostaining system (Figure 2). As a result, this could replace manual work for immunofluorescence staining experiments. Figure 2. Automatic cell immunostaining system Jie Liu, a doctoral student supported by the joint Ph.D. program between SUSTech and the Hong Kong Baptist University (HKBU), is the first author of this paper. SUSTech is the correspondence unit of this paper. The above research has been supported by the National Natural Science Foundation of China (NSFC), the National Key R&D Program of China, and the Shenzhen Science and Technology Innovation Commission. Paper link: https://doi.org/10.1002/adma.202007854
On May 22, 2021, the Department of Biomedical Engineering (BME) at the Southern University of Science and Technology (SUSTech) celebrated its 5th anniversary by holding an Achievement Exhibition. The achievement exhibition was made accessible for both online and offline participation. Yusheng ZHAO, Acting Vice President of SUSTech and Dean of the SUSTech Academy for Advanced Interdisciplinary Studies, attended the event. Yusheng ZHAO said that BME has developed rapidly in the past five years and has achieved remarkable results. He hopes that the department will continue to strengthen and grow in the future while also promoting the cross-integration of disciplines and innovation of advanced technology. Xingyu JIANG, Head of BME, expressed his gratitude to everyone who has helped and supported the development of BME over the past few years. He added that its success wouldn’t have been possible without the support of the leadership team at SUSTech, faculty members, students, and other volunteers that have assisted the department since its formation. All 17 research groups of BME participated in the exhibition, attracting more than 100 experts, scholars, faculty members, and students within SUSTech to participate in the event.
Recently, Kai Li’s laboratory at the Department of Biomedical Engineering of the Southern University of Science and Technology (SUSTech) has made significant experimental progress in tumor photodynamic immunotherapy. The research paper, titled “Acceptor Engineering for Optimized ROS Generation Facilitates Reprogramming Macrophages to M1 Phenotype in Photodynamic Immunotherapy” was published by Angewandte Chemie International Edition. Reprogramming tumor‐associated macrophage cells by photodynamic therapy (PDT) is a promising approach to overcoming the suppression of tumor microenvironment for boosted immunotherapy. It remains unclear how the reactive oxygen species (ROS) generated from type I and II mechanisms relate to the macrophage polarization efficacy. Prof. Li’s team designed and synthesized three photosensitizers with varied ROS‐generating effectiveness. Surprisingly, they discovered that the extracellular ROS generated from type I mechanisms are mainly responsible for reprogramming the macrophages from a pro‐tumor type (M2) to an anti‐tumor state (M1). In vivo experiments prove that the photosensitizer can produce effective suppression of the tumor growth, while the therapeutic outcome is eliminated with depleted macrophages. Overall, their strategy highlights the design guideline of macrophage‐activated photosensitizers. Here were the key findings from their analysis: 1. Three donor-acceptor (D-A) structured AIEgen photosensitizers have been synthesized using the compound triphenylamine as the electron donor, and their ROS-generating efficiencies are adjusted by using acceptor units with varied electron deficiencies. 2. Using commercial photosensitizers, such as chlorin 6 (Ce6) and rose bengal (RB), they discover that the extracellular ROS generated from type I mechanism rather than type II mechanism plays a key role in reprogramming the macrophages to M1 phenotype. This is of high importance in in vivo anti-tumor applications, taking into account the lower oxygen dependence of type I PDT mechanism and the hypoxic tumor microenvironment. 3. In vivo results suggest that the tTDCR nanoparticles can lead to a complete removal of a tumor in mice without any relapse, upon a single PDT treatment in the absence of any immune checkpoint inhibitor or immunoadjuvant. This would appear to be attributed to its excellent performance in the activating macrophages. Dr. Guang Yang, a post-doctoral at SUSTech, is the first author of this paper. Prof. Kai Li, also of SUSTech, is the corresponding author. Jen-Shyang Ni, Yaxi Li, Menglei Zha, and Yao Tu are the co-authors of the paper. This research was financially supported by the National Natural Science Foundation of China (NSFC), Ministry of Science and Technology of China (MOST), Guangdong Science and Technology Department, and the Shenzhen Science and Technology Program. Paper Link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202013228
Optical tweezers are widely used in materials assembly, characterization, biomechanical force sensing, and the in vivo manipulation of cells and organs. The trapping force has primarily been generated through the refractive index mismatch between a trapped object and its surrounding medium. This poses a fundamental challenge for the optical trapping of low-refractive-index nanoscale objects, including nanoparticles and intracellular organelles. Prof. Dayong Jin, Chair Professor at SUSTech Department of Biomedical Engineering (BME) and Distinguished Professor at the University of Technology Sydney (UTS), was part of an international collaborative research team that published an article on February 18, 2021, in Nature Nanotechnology, titled as “Optical tweezers beyond refractive index mismatch using highly doped upconversion nanoparticles.” The research focuses on a technology that employs a resonance effect to enhance the permittivity and polarizability of nanocrystals, leading to enhanced optical trapping forces by orders of magnitude. This effectively bypasses the requirement of refractive index mismatch at the nanoscale. Figure 1. Comparison between optical trapping of low refractive index nanoparticles with or without doping by lanthanide ions The study shows that under resonance conditions, highly doping lanthanide ions in NaYF4 nanocrystals makes the real part of the Clausius–Mossotti factor approach its asymptotic limit, thereby achieving a maximum optical trap stiffness of 0.086 pN μm–1 mW–1 for 23.3-nm-radius low-refractive-index (1.46) nanoparticles, that is, more than 30 times stronger than the reported value for gold nanoparticles of the same size. Figure 2. Escape velocity measurements to quantify the trap stiffness for HeLa cells with and without lanthanide-doped nanoparticles. In conclusion, this study discovered that highly doping lanthanide ions in single nanoparticles can generate a strong oscillation resonance effect in the electromagnetic field and thereby substantially enhance the optical trapping force. This strategy can bypass the limitation set by the refractive index mismatch between an object and its surrounding medium, suggesting a new way to design far-field optical tweezers on the nanoscale. Also, benefiting from the limited heat generation, compared with gold nanoparticles, this work opens the door to a highly efficient, long-term, optical manipulation of biological samples. Furthermore, lanthanide-doped nanoparticles can be designed to be responsive to the surrounding temperature and pH values, and to enable multimodal manipulation. Mr. Xuchen Shan from the UTS Institute for Biomedical Materials & Devices (IBMD) was the lead author of the paper. Dr. Fan Wang of UTS, Dr. Peter J. Reece of the University of New South Wales (UNSW Sydney), and Prof. Dayong Jin of SUSTech and UTS, are the corresponding authors. The scholars acknowledge financial support from a UTS Chancellor’s Postdoctoral Research Fellowship, Australian Research Council (ARC) DECRA fellowship, the ARC Discovery Project, the National Natural Science Foundation of China (NSFC), Science and Technology Innovation Commission of Shenzhen, and the Australia–China Science and Research Fund Joint Research Centre for Point-of-Care Testing. Paper link: https://www.nature.com/articles/s41565-021-00852-0