Vertically Coated Graphene Oxide Micro-Well Arrays for Highly Efficient Cancer Spheroid Formation and Drug Screening

High-Throughput Programmable Tumor Spheroid Generation Using the Magneto-Archimedes Effect

Three-dimensional (3D) tumor spheroids in vitro have great potential in drug discovery and tissue engineering due to their similarity to real tissues. Herein, we develop a simple strategy, with time and cost-effective, noninvasive characters to produce high-throughput 3D tissue spheroids using the magneto-Archimedes effect. This method is versatile in producing various morphologies of tumor spheroids by using different templates, as well as spatially coded tumor spheroids by adding different cells in the defined orders. The prepared tumor spheroids are similar to the mouse homograft tumors, as confirmed by immunofluorescence experimental results. We demonstrate that the prepared tumor spheroids can be used for anticancer drug screening, tumor inoculations, and the study of chemical signal transduction between artificial cell aggregates and tumor tissues. Temozolomide (TMZ) is found to be more effective than 5-FU toward gliomas. Further, C6 tumor spheroids are successfully inoculated into mice to grow tumors with a rapid growth rate than free cells. In the hybrid structure containing artificial cell aggregates and tumor spheroids, reactive oxygen species (H2O2) are generated in the artificial cell aggregates, which diffuse into tumor spheroids to cause the redistribution of intracellular Ca2+ in tumor cells, consequently inducing cell apoptosis. This method is easy to scale up by using large magnets. It provides great potential in complicated tissue structure construction, antitumor drug screening, and tissue engineering.

Controlled Au-coated PDMS microwell array for surface-enhanced DNA biochips

Microwell technology is crucial in biological applications due to its ability to handle small sample sizes and perform numerous assays efficiently. This study aimed to develop a novel technique for microwell fabrication using pressure-assisted steam technology, offering lower cost, simplicity, and high reproducibility. Mechanical properties of microwell surfaces were successfully controlled and characterized, making them suitable for DNA capture. The application of gold coating generated an electric field within designed microwells, facilitating stable DNA detection. These microwells exhibited effective DNA sensing capabilities, validated using fluorescently stained lambda DNA at various concentrations (86, 8.6, and 0.86 ng μL-1). In particular, the 2.8 mm microwell showed a greater change in fluorescence intensity depending on DNA concentration than other microwells. At a concentration of 0.86 ng μL-1, to assess producibility using relative standard deviation (RSD) values as a DNA sensor, they were measured as 5.29, 2.76, and 1.85% for 1, 1.7, and 2.8 mm microwells, respectively. These results indicated that our proposed microwell exhibited efficient performance and good reproducibility. We believe that the developed method could be potentially used for high-throughput analysis as a biosensor for DNA applications.

Developing Liver Microphysiological Systems for Biomedical Applications

Microphysiological systems (MPSs), also known as organ chips, are micro-units that integrate cells with diverse physical and biochemical environmental cues. In the field of liver MPSs, cellular components have advanced from simple planar cell cultures to more sophisticated 3D formations such as spheroids and organoids. Additionally, progress in microfluidic devices, bioprinting, engineering of matrix materials, and interdisciplinary technologies have significant promise for producing MPSs with biomimetic structures and functions. This review provides a comprehensive summary of biomimetic liver MPSs including their clinical applications and future developmental potential. First, the key components of liver MPSs, including the principal cell types and engineered structures utilized for cell cultivation, are briefly introduced. Subsequently, the biomedical applications of liver MPSs, including the creation of disease models, drug absorption, distribution, metabolism, excretion, and toxicity, are discussed. Finally, the challenges encountered by MPSs are summarized, and future research directions for their development are proposed.

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Graphene Oxide Nanoparticles and Organoids: A Prospective Advanced Model for Pancreatic Cancer Research

Pancreatic cancer, notorious for its grim 10% five-year survival rate, poses significant clinical challenges, largely due to late-stage diagnosis and limited therapeutic options. This review delves into the generation of organoids, including those derived from resected tissues, biopsies, pluripotent stem cells, and adult stem cells, as well as the advancements in 3D printing. It explores the complexities of the tumor microenvironment, emphasizing culture media, the integration of non-neoplastic cells, and angiogenesis. Additionally, the review examines the multifaceted properties of graphene oxide (GO), such as its mechanical, thermal, electrical, chemical, and optical attributes, and their implications in cancer diagnostics and therapeutics. GO's unique properties facilitate its interaction with tumors, allowing targeted drug delivery and enhanced imaging for early detection and treatment. The integration of GO with 3D cultured organoid systems, particularly in pancreatic cancer research, is critically analyzed, highlighting current limitations and future potential. This innovative approach has the promise to transform personalized medicine, improve drug screening efficiency, and aid biomarker discovery in this aggressive disease. Through this review, we offer a balanced perspective on the advancements and future prospects in pancreatic cancer research, harnessing the potential of organoids and GO.

3D tumor spheroids: morphological alterations a yardstick to anti-cancer drug response

Tumor spheroids are one of the well-characterized 3D culture systems bearing close resemblance to the physiological tissue organization and complexity of avascular solid tumor stage with hypoxic core. They hold a wide-spread application in the field of pharmaceutical science and anti-cancer drug research. However, the difficulty in determining optimal technique for the generation of spheroids with uniform size and shape, evaluation of experimental outputs, or mass production often limits their usage in anti-cancer research and in high-throughput drug screening. In recent times, several studies have demonstrated various simple techniques for generating uniform-size 3D spheroids, including the hanging drop (HD), liquid overlay technique (LOT), and microfluidic approaches. Morphological alterations apart from biochemical assays, and staining techniques are suitably employed for the evaluation of experimental outcomes within 3D spheroid models. Morphological alterations in response to effective anti-cancer drug treatment in 3D tumor spheroids such as reduced spheroid size, loss of spheroid compactness and integrity or smooth surface, are highly reliable. These alterations can significantly reduce the need for biochemical assays and staining techniques, resulting in both time and cost savings. The present article specifically covers a variety of available procedures in spheroid generation. For practical applicability, we have supplemented our review study with the generation of glioblastoma U87 spheroids using HD and LOT methods. Additionally, we have also incorporated the outcome of U87 spheroid treatment with doxorubicin on spheroid morphology.

PEGylated Paclitaxel Nanomedicine Meets 3D Confinement: Cytotoxicity and Cell Behaviors

Investigating the effect of nanomedicines on cancer cell behavior in three-dimensional (3D) platforms is beneficial for evaluating and developing novel antitumor nanomedicines in vitro. While the cytotoxicity of nanomedicines on cancer cells has been widely studied on two-dimensional flat surfaces, there is little work using 3D confinement to assess their effects. This study aims to address this gap by applying PEGylated paclitaxel nanoparticles (PEG-PTX NPs) for the first time to treat nasopharyngeal carcinoma (NPC43) cells in 3D confinement consisting of microwells with different sizes and a glass cover. The cytotoxicity of the small molecule drug paclitaxel (PTX) and PEG-PTX NPs was studied in microwells with sizes of 50 × 50, 100 × 100, and 150 × 150 μm² both with and without a concealed top cover. The impact of microwell confinement with varying sizes and concealment on the cytotoxicity of PTX and PEG-PTX NPs was analyzed by assessing NPC43 cell viability, migration speed, and cell morphology following treatment. Overall, microwell isolation was found to suppress drug cytotoxicity, and differences were observed in the time-dependent effects of PTX and PEG-PTX NPs on NPC43 cells in isolated and concealed microenvironments. These results not only demonstrate the effect of 3D confinement on nanomedicine cytotoxicity and cell behaviors but also provide a novel method to screen anticancer drugs and evaluate cell behaviors in vitro.

Sub-wavelength acoustic stencil for tailored micropatterning

Acoustofluidic devices are ideal for biomedical micromanipulation applications, with high biocompatibility and the ability to generate force gradients down to the scale of cells. However, complex and designed patterning at the microscale remains challenging. In this work we report an acoustofluidic approach to direct particles and cells within a structured surface in arbitrary configurations. Wells, trenches and cavities are embedded in this surface. Combined with a half-wavelength acoustic field, together these form an 'acoustic stencil' where arbitrary cell and particle arrangements can be reversibly generated. Here a bulk-wavemode lithium niobate resonator generates multiplexed parallel patterning via a multilayer resonant geometry, where cell-scale resolution is accomplished via structured sub-wavelength microfeatures. Uniquely, this permits simultaneous manipulation in a unidirectional, device-spanning single-node field across scalable ∼cm² areas in a microfluidic device. This approach is demonstrated via patterning of 5, 10 and 15 μm particles and 293-F cells in a variety of arrangements, where these activities are enabling for a range of cell studies and tissue engineering applications via the generation of highly complex and designed acoustic patterns at the microscale.

Infantile hemangioma models: is the needle in a haystack?

Infantile hemangioma (IH) is the most prevalent benign vascular tumor in infants, with distinct disease stages and durations. Despite the fact that the majority of IHs can regress spontaneously, a small percentage can cause disfigurement or even be fatal. The mechanisms underlying the development of IH have not been fully elucidated. Establishing stable and reliable IH models provides a standardized experimental platform for elucidating its pathogenesis, thereby facilitating the development of new drugs and the identification of effective treatments. Common IH models include the cell suspension implantation model, the viral gene transfer model, the tissue block transplantation model, and the most recent three-dimensional (3D) microtumor model. This article summarizes the research progress and clinical utility of various IH models, as well as the benefits and drawbacks of each. Researchers should select distinct IH models based on their individual research objectives to achieve their anticipated experimental objectives, thereby increasing the clinical relevance of their findings.

Three-Dimensional Microtumor Formation of Infantile Hemangioma-Derived Endothelial Cells for Mechanistic Exploration and Drug Screening

Infantile hemangioma (IH) is the most prevalent type of vascular tumor in infants. The pathophysiology of IH is unknown. The tissue structure and physiology of two-dimensional cell cultures differ greatly from those in vivo, and spontaneous regression often occurs during tumor formation in nude mice and has severely limited research into the pathogenesis and development of IH. By decellularizing porcine aorta, we attempted to obtain vascular-specific extracellular matrix as the bioink for fabricating micropattern arrays of varying diameters via microcontact printing. We then constructed IH-derived CD31+ hemangioma endothelial cell three-dimensional microtumor models. The vascular-specific and decellularized extracellular matrix was suitable for the growth of infantile hemangioma-derived endothelial cells. The KEGG signaling pathway analysis revealed enrichment primarily in stem cell pluripotency, RAS, and PI3KAkt compared to the two-dimensional cell model according to RNA sequencing. Propranolol, the first-line medication for IH, was also used to test the model's applicability. We also found that metformin had some impact on the condition. The three-dimensional microtumor models of CD31+ hemangioma endothelial cells were more robust and efficient experimental models for IH mechanistic exploration and drug screening.

Self-Assembled Peptide Habitats to Model Tumor Metastasis

Metastatic tumours are complex ecosystems; a community of multiple cell types, including cancerous cells, fibroblasts, and immune cells that exist within a supportive and specific microenvironment. The interplay of these cells, together with tissue specific chemical, structural and temporal signals within a three-dimensional (3D) habitat, direct tumour cell behavior, a subtlety that can be easily lost in 2D tissue culture. Here, we investigate a significantly improved tool, consisting of a novel matrix of functionally programmed peptide sequences, self-assembled into a scaffold to enable the growth and the migration of multicellular lung tumour spheroids, as proof-of-concept. This 3D functional model aims to mimic the biological, chemical, and contextual cues of an in vivo tumor more closely than a typically used, unstructured hydrogel, allowing spatial and temporal activity modelling. This approach shows promise as a cancer model, enhancing current understandings of how tumours progress and spread over time within their microenvironment.

Pairing cells of different sizes in a microfluidic device for immunological synapse monitoring

Analyzing cell-cell interaction is essential to investigate how immune cells function. Elegant designs have been demonstrated to study lymphocytes and their interaction partners. However, these devices have been targeting cells of similar dimensions. T lymphocytes are smaller, more deformable, and more sensitive to pressure than many cells. This work aims to fill the gap of a method for pairing cells with different dimensions. The developed method uses hydrodynamic flow focusing in the z-direction for on-site modulation of effective channel height to capture smaller cells as single cells. Due to immune cells' sensitivity to pressure, the proposed method provides a stable system without any change in flow conditions at the analysis area throughout experiments. Paired live cells have their activities analyzed with calcium imaging at the immunological synapse formed under a controlled environment. The method is demonstrated with primary human T lymphocytes, acute myeloid leukemia (AML) cell lines, and primary AML blasts.

Fabrication of Size-Controllable and Arrangement-Orderly HepG2 Spheroids for Drug Screening via Decellularized Liver Matrix-Derived Micropattern Array Chips

Three-dimensional (3D) culture via micropattern arrays to generate cellular spheroids seems a promising in vitro biomimetic system for liver tissue engineering applications, such as drug screening. Recently, organ-derived decellularized extracellular matrix emerges as arguably the most biomimetic bioink. Herein, decellularized liver matrix (DLM)-derived micropattern array chips were developed to fabricate size-controllable and arrangement-orderly HepG2 spheroids for drug screening. The porcine DLM was obtained by the removal of cellular components and then ground into powder, followed by enzymolysis. DLM as a coating substrate was compared with collagen type I (Col I) and Matrigel in terms of biological performance for enhancing cell adhesion, proliferation, and functions. Subsequently, we used poly(dimethylsiloxane) (PDMS) to adsorb DLM as the bioink to fabricate micropattern array chips. The optimal shape and size of micropattern were determined by evaluating the morphology, viability, and functions of HepG2 3D cellular aggregates. In addition, drug-susceptibility testing (paclitaxel, doxorubicin HCl, and disulfiram) was performed on this novel platform. The DLM provided the tissue-specific microenvironment that provided suitable supports for HepG2 cells, compared to Col I and Matrigel. A circular micropattern with a diameter of 100 μm was the optimal processing parameter to rapidly fabricate large-scale, size-controllable, and arrangement-orderly HepG2 cellular aggregates with 3D spheroid’s shape and high cell viability. Drug screening testing showed that the effect of a drug could be directly demonstrated on-chip by confocal microscopy measuring the viability of spheroids. We provide a novel platform for the large-scale generation of HepG2 spheroids with uniform size and arrangement, thus bringing convenience, reducing error, and increasing reproducibility for a rapid drug discovery by fluorescence quantitative analysis. This methodology may be possible to apply in advancing personalized medicine and drug discovery.

Nano-sized graphene oxide coated nanopillars on microgroove polymer arrays that enhance skeletal muscle cell differentiation

The degeneration or loss of skeletal muscles, which can be caused by traumatic injury or disease, impacts most aspects of human activity. Among various techniques reported to regenerate skeletal muscle tissue, controlling the external cellular environment has been proven effective in guiding muscle differentiation. In this study, we report a nano-sized graphene oxide (sGO)-modified nanopillars on microgroove hybrid polymer array (NMPA) that effectively controls skeletal muscle cell differentiation. sGO-coated NMPA (sG-NMPA) were first fabricated by sequential laser interference lithography and microcontact printing methods. To compensate for the low adhesion property of polydimethylsiloxane (PDMS) used in this study, graphene oxide (GO), a proven cytophilic nanomaterial, was further modified. Among various sizes of GO, sGO (< 10 nm) was found to be the most effective not only for coating the surface of the NM structure but also for enhancing the cell adhesion and spreading on the fabricated substrates. Remarkably, owing to the micro-sized line patterns that guide cellular morphology to an elongated shape and because of the presence of sGO-modified nanostructures, mouse myoblast cells (C2C12) were efficiently differentiated into skeletal muscle cells on the hybrid patterns, based on the myosin heavy chain expression levels. Therefore, the developed sGO coated polymeric hybrid pattern arrays can serve as a potential platform for rapid and highly efficient in vitro muscle cell generation.

Recent Advances in Multicellular Tumor Spheroid Generation for Drug Screening

Multicellular tumor spheroids (MCTs) have been employed in biomedical fields owing to their advantage in designing a three-dimensional (3D) solid tumor model. For controlling multicellular cancer spheroids, mimicking the tumor extracellular matrix (ECM) microenvironment is important to understand cell-cell and cell-matrix interactions. In drug cytotoxicity assessments, MCTs provide better mimicry of conventional solid tumors that can precisely represent anticancer drug candidates' effects. To generate incubate multicellular spheroids, researchers have developed several 3D multicellular spheroid culture technologies to establish a research background and a platform using tumor modelingvia advanced materials science, and biosensing techniques for drug-screening. In application, drug screening was performed in both invasive and non-invasive manners, according to their impact on the spheroids. Here, we review the trend of 3D spheroid culture technology and culture platforms, and their combination with various biosensing techniques for drug screening in the biomedical field.

Extremely Uniform Graphene Oxide Thin Film as a Universal Platform for One-Step Biomaterial Patterning

Graphene oxide (GO) has proven to be a highly promising material across various biomedical research avenues, including cancer therapy and stem cell-based regenerative medicine. However, creating a uniform GO coating as a thin layer on desired substrates has been considered challenging owing to the intrinsic variability of the size and shape of GO. Herein, a new method is introduced that enables highly uniform GO thin film (UGTF) fabrication on various biocompatible substrates. By optimizing the composition of the GO suspension and preheating process to the substrates, the "coffee-ring effect" is significantly suppressed. After applying a special postsmoothing process referred to as the low-oxygen concentration and low electrical energy plasma (LOLP) treatment, GO is converted to small fragments with a film thickness of up to several nanometers (≈5.1 nm) and a height variation of only 0.6 nm, based on atomic force microscopy images. The uniform GO thin film can also be generated as periodic micropatterns on glass and polymer substrates, which are effective in one-step micropatterning of both antibodies and mouse melanoma cells (B16-F10). Therefore, it can be concluded that the developed UGTF is useful for various graphene-based biological applications.

Production of Multiple Cell-Laden Microtissue Spheroids with a Biomimetic Hepatic-Lobule-Like Structure

The construction of an in vitro 3D cellular model to mimic the human liver is highly desired for drug discovery and clinical applications, such as patient-specific treatment and cell-based therapy in regenerative medicine. However, current bioprinting strategies are limited in their ability to generate multiple cell-laden microtissues with biomimetic structures. This study presents a method for producing hepatic-lobule-like microtissue spheroids using a bioprinting system incorporating a precursor cartridge and microfluidic emulsification system. The multiple cell-laden microtissue spheroids can be successfully generated at a speed of approximately 45 spheroids min-1 and with a uniform diameter. Hepatic and endothelial cells are patterned in a microtissue spheroid with the biomimetic structure of a liver lobule. The spheroids allow long-term culture with high cell viability, and the structural integrity is maintained longer than that of non-structured spheroids. Furthermore, structured spheroids show high MRP2, albumin, and CD31 expression levels. In addition, the in vivo study reveals that structured microtissue spheroids are stably engrafted. These results demonstrate that the method provides a valuable 3D structured microtissue spheroid model with lobule-like constructs and liver functions.

Rapid Formation of Stem Cell Spheroids Using Two-Dimensional MXene Particles

Cell spheroids have been studied as a biomimic medicine for tissue healing using cell sources. Rapid cell spheroid production increases cell survival and activity as well as the efficiency of mass production by reducing processing time. In this study, two-dimensional MXene (Ti3C2) particles were used to form mesenchymal stem cell spheroids, and the optimal MXene concentration, spheroid-production times, and bioactivity levels of spheroid cells during this process were assessed. A MXene concentration range of 1 to 10 μg/mL induced spheroid formation within 6 h. The MXene-induced spheroids exhibited osteogenic-differentiation behavior, with the highest activity levels at a concentration of 5 μg/mL. We report a novel and effective method for the rapid formation of stem cell spheroids using MXene.

Graphene Hybrid Materials for Controlling Cellular Microenvironments

Cellular microenvironments are known as key factors controlling various cell functions, including adhesion, growth, migration, differentiation, and apoptosis. Many materials, including proteins, polymers, and metal hybrid composites, are reportedly effective in regulating cellular microenvironments, mostly via reshaping and manipulating cell morphologies, which ultimately affect cytoskeletal dynamics and related genetic behaviors. Recently, graphene and its derivatives have emerged as promising materials in biomedical research owing to their biocompatible properties as well as unique physicochemical characteristics. In this review, we will highlight and discuss recent studies reporting the regulation of the cellular microenvironment, with particular focus on the use of graphene derivatives or graphene hybrid materials to effectively control stem cell differentiation and cancer cell functions and behaviors. We hope that this review will accelerate research on the use of graphene derivatives to regulate various cellular microenvironments, which will ultimately be useful for both cancer therapy and stem cell-based regenerative medicine.