A facile method to prepare superparamagnetic iron oxide and hydrophobic drug-encapsulated biodegradable polyurethane nanoparticles

Droplet-based microfluidics: an efficient high-throughput portable system for cell encapsulation

One of the goals of tissue engineering and regenerative medicine is restoring primary living tissue function by manufacturing a 3D microenvironment. One of the main challenges is protecting implanted non-autologous cells or tissues from the host immune system. Cell encapsulation has emerged as a promising technique for this purpose. It involves entrapping cells in biocompatible and semi-permeable microcarriers made from natural or synthetic polymers that regulate the release of cellular secretions. In recent years, droplet-based microfluidic systems have emerged as powerful tools for cell encapsulation in tissue engineering and regenerative medicine. These systems offer precise control over droplet size, composition, and functionality, allowing for creating of microenvironments that closely mimic native tissue. Droplet-based microfluidic systems have extensive applications in biotechnology, medical diagnosis, and drug discovery. This review summarises the recent developments in droplet-based microfluidic systems and cell encapsulation techniques, as well as their applications, advantages, and challenges in biology and medicine. The integration of these technologies has the potential to revolutionise tissue engineering and regenerative medicine by providing a precise and controlled microenvironment for cell growth and differentiation. By overcoming the immune system's challenges and enabling the release of cellular secretions, these technologies hold great promise for the future of regenerative medicine.

A Printable Magnetic-Responsive Iron Oxide Nanoparticle (ION)-Gelatin Methacryloyl (GelMA) Ink for Soft Bioactuator/Robot Applications

The features or actuation behaviors of nature's creatures provide concepts for the development of biomimetic soft bioactuators/robots with stimuli-responsive capabilities, design convenience, and environmental adaptivity in various fields. Mimosa pudica is a mechanically responsive plant that can convert pressure to the motion of leaves. When the leaves receive pressure, the occurrence of asymmetric turgor in the extensor and flexor sides of the pulvinus from redistributing the water in the pulvinus causes the bending of the pulvinus. Inspired by the actuation of Mimosa pudica, designing soft bioactuators can convert external stimulations to driving forces for the actuation of constructs which has been receiving increased attention and has potential applications in many fields. 4D printing technology has emerged as a new strategy for creating versatile soft bioactuators/robots by integrating printing technologies with stimuli-responsive materials. In this study, we developed a hybrid ink by combining gelatin methacryloyl (GelMA) polymers with iron oxide nanoparticles (IONs). This hybrid ION-GelMA ink exhibits tunable rheology, controllable mechanical properties, magnetic-responsive behaviors, and printability by integrating the internal metal ion-polymeric chain interactions and photo-crosslinking chemistries. This design offers the inks a dual crosslink mechanism combining the advantages of photocrosslinking and ionic crosslinking to rapidly form the construct within 60 s of UV exposure time. In addition, the magnetic-responsive actuation of ION-GelMA constructs can be regulated by different ION concentrations (0-10%). Furthermore, we used the ION-GelMA inks to fabricate a Mimosa pudica-like soft bioactuator through a mold casting method and a direct-ink-writing (DIW) printing technology. Obviously, the pinnule leaf structure of printed constructs presents a continuous reversible shape transformation in an air phase without any liquid as a medium, which can mimic the motion characteristics of natural creatures. At the same time, compared to the model casting process, the DIW printed bioactuators show a more refined and biomimetic transformation shape that closely resembles the movement of the pinnule leaf of Mimosa pudica in response to stimulation. Overall, this study indicates the proof of concept and the potential prospect of magnetic-responsive ION-GelMA inks for the rapid prototyping of biomimetic soft bioactuators/robots with untethered non-contact magneto-actuations.

Biological Effects, Applications and Design Strategies of Medical Polyurethanes Modified by Nanomaterials

Polyurethane (PU) has wide application and popularity as medical apparatus due to its unique structural properties relationship. However, there are still some problems with medical PUs, such as a lack of functionality, insufficient long-term implantation safety, undesired stability, etc. With the rapid development of nanotechnology, the nanomodification of medical PU provides new solutions to these clinical problems. The introduction of nanomaterials could optimize the biocompatibility, antibacterial effect, mechanical strength, and degradation of PUs via blending or surface modification, therefore expanding the application range of medical PUs. This review summarizes the current applications of nano-modified medical PUs in diverse fields. Furthermore, the underlying mechanisms in efficiency optimization are analyzed in terms of the enhanced biological and mechanical properties critical for medical use. We also conclude the preparation schemes and related parameters of nano-modified medical PUs, with discussions about the limitations and prospects. This review indicates the current status of nano-modified medical PUs and contributes to inspiring novel and appropriate designing of PUs for desired clinical requirements.

D-Alpha-Tocopheryl Poly(ethylene Glycol 1000) Succinate-Coated Manganese-Zinc Ferrite Nanomaterials for a Dual-Mode Magnetic Resonance Imaging Contrast Agent and Hyperthermia Treatments

Manganese-zinc ferrite (MZF) is known as high-performance magnetic material and has been used in many fields and development. In the biomedical applications, the biocompatible MZF formulation attracted much attention. In this study, water-soluble amphiphilic vitamin E (TPGS, d-alpha-tocopheryl poly(ethylene glycol 1000) succinate) formulated MZF nanoparticles were synthesized to serve as both a magnetic resonance imaging (MRI) contrast agent and a vehicle for creating magnetically induced hyperthermia against cancer. The MZF nanoparticles were synthesized from a metallic acetylacetonate in an organic phase and further modified with TPGS using an emulsion and solvent-evaporation method. The resulting TPGS-modified MZF nanoparticles exhibited a dual-contrast ability, with a longitudinal relaxivity (35.22 s−1 mM Fe−1) and transverse relaxivity (237.94 s−1 mM Fe−1) that were both higher than Resovist®. Furthermore, the TPGS-assisted MZF formulation can be used for hyperthermia treatment to successfully suppress cell viability and tumor growth after applying an alternating current (AC) electromagnetic field at lower amplitude. Thus, the TPGS-assisted MZF theranostics can not only be applied as a potential contrast agent for MRI but also has potential for use in hyperthermia treatments.

Composite Materials Based on Iron Oxide Nanoparticles and Polyurethane for Improving the Quality of MRI

Polyether urethane (PU)-based magnetic composite materials, containing different types and concentrations of iron oxide nanostructures (Fe₂O₃ and Fe₃O₄), were prepared and investigated as a novel composite platform that could be explored in different applications, especially for the improvement of the image quality of MRI investigations. Firstly, the PU structure was synthetized by means of a polyaddition reaction and then hematite (Fe₂O₃) and magnetite (Fe₃O₄) nanoparticles were added to the PU matrices to prepare magnetic nanocomposites. The type and amount of iron oxide nanoparticles influenced its structural, morphological, mechanical, dielectric, and magnetic properties. Thus, the morphology and wettability of the PU nanocomposites surfaces presented different behaviours depending on the amount of the iron oxide nanoparticles embedded in the matrices. Mechanical, dielectric, and magnetic properties were enhanced in the composites’ samples when compared with pristine PU matrix. In addition, the investigation of in vitro cytocompatibility of prepared PU nanocomposites showed that these samples are good candidates for biomedical applications, with cell viability levels in the range of 80–90%. Considering all the investigations, we can conclude that the addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work.

Research on Mechanism of Superparamagnetic Iron Oxide Nanoparticles in Activating Endoplasmic Reticulum and Prompting Apoptosis of Liver Cells Through Mediation of Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1 (TNF-α/TNFR1) Pathway

The aim of this study was to assess mechanism of superparamagnetic iron oxide nanoparticles (SPIO-NPs) in activating endoplasmic reticulum (ER) and prompting apoptosis of liver cells through mediating the TNF-α/TNFR1 pathway. The SPIO-NPs were prepared and identified, and HegG2 cells were cultivated in vitro, and their apoptosis was detected. The specific pathogen-free (SPF)-grade rats were divided into several groups; which included blank group, low concentration group, high concentration group and control group. The enzymatic activity of Caspase-3 in liver tissue was tested, and expressions of Caspase-3, Bax, Bcl-2, TNF-α, p-TNFR1, IRE1α, and eIF2α were tested. The size of prepared SPIO-NPs was 7.5 nm and there was no coagulation. There was good dispersity and electric potential, and appearance was stable. The apoptotic rate in the high concentration group was notably higher than in the other groups. There was notable inflammatory cell infiltration in the high concentration group, where quantity of apoptosis was highest. The quantity of apoptosis and fluorocyte in the high concentration group were notably higher than in the other groups. Moreover, there were over expressions of Caspase-3, Bax, Caspase-3, p-TNFR1, IRE1α, and eIF2α in the high concentration group while the expression of TNF-α was lowest. The apoptosis of HegG2 cells was prompted by SPIO-NPs, and quantity of apoptosis was increased with increased adopted concentration. The active expression of p-TNFR1, IRE1α, and eIF2α could be prompted to reduce the expression of TNF-α and increase the expression of Caspase-3 and Bax for prompting the apoptosis.

Enhancing curcumin's solubility and antibiofilm activity via silica surface modification

Bacterial biofilms are microbial communities in which bacterial cells in sessile state are mechanically and chemically protected against foreign agents, thus enhancing antibiotic resistance. The delivery of active compounds to the inside of biofilms is often hindered due to the existence of the biofilm extracellular polymeric substances (EPS) and to the poor solubility of drugs and antibiotics. A possible strategy to overcome the EPS barrier is the incorporation of antimicrobial agents into a nanocarrier, able to penetrate the matrix and deliver the active substance to the cells. Here, we report the synthesis of antimicrobial curcumin-conjugated silica nanoparticles (curc-NPs) as a possibility for dealing with these issues. Curcumin is a known antimicrobial agent and to overcome its low solubility in water it was grafted onto the surface of silica nanoparticles, the latter functioning as nanocarrier for curcumin into the biofilm. Curc-NPs were able to impede the formation of model P. putida biofilms up to 50% and disrupt mature biofilms up to 54% at 2.5 mg mL^-1. Cell viability of sessile cells in both cases was also considerably affected, which is not observed for curcumin delivered as a free compound at the same concentration. Furthermore, proteomics of extracted EPS matrix of biofilms grown in the presence of free curcumin and curc-NPs revealed differences in the expression of key proteins related to cell detoxification and energy production. Therefore, curc-NPs are presented here as an alternative for curcumin delivery that can be exploited not only to other bacterial strains but also to further biological applications.

Encapsulation of gadolinium ferrite nanoparticle in generation 4.5 poly(amidoamine) dendrimer for cancer theranostics applications using low frequency alternating magnetic field

Iron oxide-based magnetic resonance imaging (MRI) contrast agents have negative contrast limitations in cancer diagnosis. Gadolinium (Gd)-based contrast agents show toxicity. To overcome these limitations, Gd-doped ferrite (Gd:Fe₃O₄ (GdIO) nanoparticles (NPs) were synthesized as T1-T2 dual-modal contrast agents for MRI-traced drug delivery. A theranostics GdIO encapsulated in a Generation 4.5 PAMAM dendrimer (G4.5-GdIO) was developed by alkaline coprecipitation. The drug-loading efficiency of the NPs was ∼24%. In the presence of a low-frequency alternating magnetic field (LFAMF), a maximum cumulative doxorubicin (DOX) release of ∼77.47% was achieved in a mildly acidic (pH = 5.0) simulated endosomal microenvironment. Relaxometric measurements indicated superior r1 (5.19 mM^-1s^-1) and r2 (26.13 mM^-1s^-1) for G4.5-GdIO relative to commercially available Gd-DTPA. Thus, G4.5-GdIO is promising as an alternative noninvasive MRI-traced cancer drug delivery system.

Biodegradable water-based polyurethane scaffolds with a sequential release function for cell-free cartilage tissue engineering

Three-dimensional (3D) printing technology has rapidly developed as a promising technology for manufacturing tissue engineering scaffolds. Cells used in tissue engineering are subjected to the quality management and risk of contamination, while cell-free scaffolds may not have sufficient therapeutic efficacy. In this study, water-based 3D printing ink containing biodegradable polyurethane (PU), chemokine SDF-1, and Y27632 drug-embedding PU microspheres was printed at low temperature (-40 °C) to fabricate tissue engineering scaffolds with sequential drug release function. The scaffolds containing 200 ng/ml SDF-1 and 22 wt% Y27632-encapsulated microspheres (55 µg/ml Y27632 in microspheres) (abbreviated PU/SDF-1/MS_Y scaffolds) had the optimal performance. The structural design of the scaffolds allowed each of SDF-1 and Y27632 to be released sequentially in vitro and reach the effective concentration (∼100 ng/ml and 3.38 µg/ml, respectively) after the appropriate time (24 h and 62 h, respectively). Human mesenchymal stem cells (hMSCs) seeded in the scaffolds showed significant GAG deposition in 7 days. Besides, the gradual release of SDF-1 from the PU/SDF-1/MS_Y scaffolds could induce the migration of hMSCs. Implantation of the cell-free PU/SDF-1/MS_Y scaffolds in rabbit articular cartilage defects supported the potential of the scaffolds to promote cartilage regeneration. The 3D printed scaffolds with sequential releases of SDF-1 and Y27632 may have potential in cartilage tissue engineering. STATEMENT OF SIGNIFICANCE: The clinical success of tissue engineering depends highly on the quality of externally supplied cells, while cell-free scaffolds may not have sufficient therapeutic efficacy. In this manuscript, water-based 3D printing ink containing biodegradable polyurethane (PU), chemokine SDF-1, and Y27632 drug-embedding PU microspheres was printed at low temperature to fabricate tissue engineering scaffolds with sequential drug release function. The structural design of the scaffolds allowed each of SDF-1 and Y27632 to be released sequentially in vitro. SDF-1 was released earlier from the scaffolds to promote cell migration. The drug Y27632 was released later from the microspheres into the matrix of the scaffolds to induce the chondrogenic differentiation of the attracted cells. Implantation of the cell-free PU/SDF-1/MS_Y scaffolds in rabbit articular cartilage defects supported the potential of the scaffolds to promote cartilage regeneration. We hypothesized that the cell-free scaffolds may improve the clinical applicability and convenience without the use of exogenous cells or growth factor.

Polyurethane Nanoparticle-Loaded Fenofibrate Exerts Inhibitory Effects on Nonalcoholic Fatty Liver Disease in Mice

Polyurethane (PU) nanoparticles are potential drug carriers. We aimed to study the in vitro and in vivo efficacy of biodegradable PU nanoparticles loaded with fenofibrate (FNB-PU) on nonalcoholic fatty liver disease (NAFLD). FNB-PU was prepared by a green process, and its preventive effects on NAFLD were investigated on HepG2 cells and mice. FNB-PU showed sustained in vitro FNB release profile. Compared to FNB crude drug, FNB-PU significantly decreased triglyceride content in HepG2 cells incubated with oleic acid and in livers of mice with NAFLD induced by a methionine choline deficient diet, and increased plasma FNB concentration of the mice. FNB-PU increased absorption of FNB and therefore enhanced the inhibitory effects of FNB on NAFLD.

A bone-resorption surface-targeting nanoparticle to deliver anti-miR214 for osteoporosis therapy

With increasing fracture risks due to fragility, osteoporosis is a global health problem threatening postmenopausal women. In these patients, osteoclasts play leading roles in bone loss and fracture. How to inhibit osteoclast activity is the key issue for osteoporosis treatment. In recent years, miRNA-based gene therapy through gene regulation has been considered a potential therapeutic method. However, in light of the side effects, the use of therapeutic miRNAs in osteoporosis treatment is still limited by the lack of tissue/cell-specific delivery systems. Here, we developed polyurethane (PU) nanomicelles modified by the acidic peptide Asp⁸. Our data showed that without overt toxicity or eliciting an immune response, this delivery system encapsulated and selectively deliver miRNAs to OSCAR⁺ osteoclasts at bone-resorption surface in vivo. With the Asp⁸-PU delivery system, anti-miR214 was delivered to osteoclasts, and bone microarchitecture and bone mass were improved in ovariectomized osteoporosis mice. Therefore, Asp⁸-PU could be a useful bone-resorption surface-targeting delivery system for treatment of osteoclast-induced bone diseases and aging-related osteoporosis.