Porous cage-derived nanomaterial inks for direct and internal three-dimensional printing

Cargo-loaded lipid-shielded breakable organosilica nanocages for enhanced drug delivery

The recent nanomedicine advancements have introduced a variety of smart nanoparticles in cancer treatment and diagnostics. However, their application to the clinic is still hindered by several challenges related to their biocompatibility, elimination and biodistribution. Here we propose breakable organosilica mesoporous nanoparticles, i.e. nanocages, able to efficiently incorporate cargo molecules and be coated, with different lipid compositions, to enhance their biomimetic behaviour. We exploit the electrostatic interactions between the organosilica surface and the opposite charge of the lipid mixtures in order to obtain an efficient organosilica coverage. The lipid-coated nanocages are proved to have an incredibly high hemocompatibility, significantly increased with respect to pristine nanocages, and excellent colloidal stability and biocompatibility. The cargo-loaded and lipid-coated nanocages are tested and compared in vitro on two different cancer cell lines, demonstrating the key role played by the lipid coating in mediating the internalization of the nanocages, evaluated by the enhanced and rapid cellular uptake. The efficient intracellular delivery of the therapeutic agents is then assured by the destruction of the organosilica, due to the disulfide bridges, introduced into the silica framework, that in reducing media, like the intracellular one, are reduced to thiols causing the breaking of the nanoparticles. The possibility to image and effectively kill cancer cells demonstrates the potentiality of the lipid-coated nanocages as a powerful tool in anticancer research and as a promising smart theranostic platform.

Construction of Photoresponsive 3D Structures Based on Triphenylethylene Photochromic Building Blocks

Photoresponsive materials have been widely used in sensing, bioimaging, molecular switches, information storage, and encryption nowadays. Although a large amount of photoresponsive materials have been reported, the construction of these smart materials into precisely prescribed complex 3D geometries is rarely studied. Here we designed a novel photoresponsive material methyl methacrylate containing triphenylethylene (TrPEF₂-MA) that can be directly used for digital light processing (DLP) 3D printing. Based on TrPEF₂-MA, a series of photoresponsive 3D structures with reversible color switching under ultraviolet/visible light irradiations were fabricated. These complex photoresponsive 3D structures show high resolutions (50 μm), excellent repeatability (25 cycles without fatigue), and tunable saturate color degrees. Multicomponent DLP 3D printing processes were also carried out to demonstrate their great properties in information hiding and information-carrying properties. This design strategy for constructing photoresponsive 3D structures is attractive in the area of adaptive camouflage, information hiding, information storage, and flexible electronics.

Tailoring thermal insulation architectures from additive manufacturing

Tailoring thermal transport by structural parameters could result in mechanically fragile and brittle networks. An indispensable goal is to design hierarchical architecture materials that combine thermal and mechanical properties in a continuous and cohesive network. A promising strategy to create such a hierarchical network targets additive manufacturing of hybrid porous voxels at nanoscale. Here we describe the convergence of agile additive manufacturing of porous hybrid voxels to tailor hierarchically and mechanically tunable objects. In one strategy, the uniformly distributed porous silica voxels, which form the basis for the control of thermal transport, are non-covalently interfaced with polymeric networks, yielding hierarchic super-elastic architectures with thermal insulation properties. Another additive strategy for achieving mechanical strength involves the versatile orthogonal surface hybridization of porous silica voxels retains its low thermal conductivity of 19.1 mW m⁻¹K⁻¹, flexible compressive recovery strain (85%), and tailored mechanical strength from 71.6 kPa to 1.5 MPa. The printed lightweight high-fidelity objects promise thermal aging mitigation for lithium-ion batteries, providing a thermal management pathway using 3D printed silica objects.

Nanoscale porous building blocks hold great promise for a range of thermal management technologies but often porous nanoparticle assemblies are intrinsically brittle. Here, the authors report 3D printing of porous silica voxels with polymeric additives to enable the coupling between additive manufacturing and hierarchical assembly for superior machinability and structural controllability.

Advances in Digital Light Processing of Hydrogels

Hydrogels, three-dimensional (3D) networks of hydrophilic polymers formed in water, are a significant type of soft matter used in fundamental and applied sciences. Hydrogels are of particular interest for biomedical applications, owing to their soft elasticity and good biocompatibility. However, the high water content and soft nature of hydrogels often make it difficult to process them into desirable solid forms. The development of 3D printing (3DP) technologies has provided opportunities for the manufacturing of hydrogels, by adopting a freeform fabrication method. Owing to its high printing speed and resolution, vat photopolymerization 3DP has recently attracted considerable interest for hydrogel fabrication, with digital light processing (DLP) becoming a widespread representative technique. Whilst acknowledging that other types of vat photopolymerization 3DP have also been applied for this purpose, we here only focus on DLP and its derivatives. In this review, we first comprehensively outline the most recent advances in both materials and fabrication, including the adaptation of novel hydrogel systems and advances in processing (e.g., volumetric printing and multimaterial integration). Secondly, we summarize the applications of hydrogel DLP, including regenerative medicine, functional microdevices, and soft robotics. To the best of our knowledge, this is the first time that either of these specific review focuses has been adopted in the literature. More importantly, we discuss the major challenges associated with hydrogel DLP and provide our perspectives on future trends. To summarize, this review aims to aid and inspire other researchers investigatng DLP, photocurable hydrogels, and the research fields related to them.

High Precision 3D Printing for Micro to Nano Scale Biomedical and Electronic Devices

Three dimensional printing (3DP), or additive manufacturing, is an exponentially growing process in the fabrication of various technologies with applications in sectors such as electronics, biomedical, pharmaceutical and tissue engineering. Micro and nano scale printing is encouraging the innovation of the aforementioned sectors, due to the ability to control design, material and chemical properties at a highly precise level, which is advantageous in creating a high surface area to volume ratio and altering the overall products' mechanical and physical properties. In this review, micro/-nano printing technology, mainly related to lithography, inkjet and electrohydrodynamic (EHD) printing and their biomedical and electronic applications will be discussed. The current limitations to micro/-nano printing methods will be examined, covering the difficulty in achieving controlled structures at the miniscule micro and nano scale required for specific applications.

Bioprinting and regeneration of auricular cartilage using a bioactive bioink based on microporous photocrosslinkable acellular cartilage matrix

Tissue engineering provides a promising strategy for auricular reconstruction. Although the first international clinical breakthrough of tissue-engineered auricular reconstruction has been realized based on polymer scaffolds, this approach has not been recognized as a clinically available treatment because of its unsatisfactory clinical efficacy. This is mainly since reconstruction constructs easily cause inflammation and deformation. In this study, we present a novel strategy for the development of biological auricle equivalents with precise shapes, low immunogenicity, and excellent mechanics using auricular chondrocytes and a bioactive bioink based on biomimetic microporous methacrylate-modified acellular cartilage matrix (ACMMA) with the assistance of gelatin methacrylate (GelMA), poly(ethylene oxide) (PEO), and polycaprolactone (PCL) by integrating multi-nozzle bioprinting technology. Photocrosslinkable ACMMA is used to emulate the intricacy of the cartilage-specific microenvironment for active cellular behavior, while GelMA, PEO, and PCL are used to balance printability and physical properties for precise structural stability, form the microporous structure for unhindered nutrient exchange, and provide mechanical support for higher shape fidelity, respectively. Finally, mature auricular cartilage-like tissues with high morphological fidelity, excellent elasticity, abundant cartilage lacunae, and cartilage-specific ECM deposition are successfully regenerated in vivo, which provides new opportunities and novel strategies for the fabrication and regeneration of patient-specific auricular cartilage.

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Comprehensive proteomic characteristics of the acellular cartilage matrix.

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Bioactive bioink based on ACMMA, GelMA, and PEO promoted cell behavior.

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Bioactive bioink contained biomimetic ECM components and microporous structure.

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Higher biomechanics was provided by alternately bioactive bioink and PCL strands.

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Mature auricle cartilage with high shape fidelity and good mechanics was regenerated.

Recent progress in acoustic field-assisted 3D-printing of functional composite materials

Acoustic forces are an attractive pathway to achieve directed assembly for multi-phase materials via additive processes. Programmatic integration of microstructure and structural features during deposition offers opportunities for optimizing printed component performance. We detail recent efforts to integrate acoustic focusing with a direct-ink-write mode of printing to modulate material transport properties (e.g. conductivity). Acoustic field-assisted printing, operating under a multi-node focusing condition, supports deposition of materials with multiple focused lines in a single-pass printed line. Here, we report the demonstration of acoustic focusing in concert with diffusive self-assembly to rapidly assembly and print multiscale, mm-length colloidal solids on a timescale of seconds to minutes. These efforts support the promising capabilities of acoustic field-assisted deposition-based printing to achieve spatial control of printed microstructures with deterministic, long-range ordering across multiple length scales.

Processing-Structure-Performance Relationships of Microporous Metal-Organic Polymers for Size-Selective Separations

Small-molecule impurities, such as N-nitrosodimethylamine (NDMA), have infiltrated the generic drug industry, leading to recalls in commonly prescribed blood pressure and stomach drugs in over 43 countries since 2018 and directly affecting tens of millions of patients. One promising strategy to remove small-molecule impurities like NDMA from drug molecules is by size exclusion, in which the contaminant is removed by selective adsorption onto a (micro)porous material due to its smaller size. However, current solution-phase size-exclusion separations are primarily limited by the throughput-selectivity trade-off. Here, we report a bioinspired solution to conquer these critical challenges by leveraging the assembly of atomically precise building blocks into hierarchically porous structures. We introduce a bottom-up approach to form micropores, mesopores, and macroscopic superstructures simultaneously using functionalized oxozirconium clusters as building blocks. Further, we leverage recent advances in photopolymerization to design macroscopic flow structures to mitigate backpressure. Based on these multiscale design principles, we engineer simple, inexpensive devices that are able to separate NDMA from contaminated drugs. Beyond this urgent model system, we expect this design strategy to open up hitherto unexplored avenues of nanomaterial superstructure fabrication for a range of size-exclusion purification strategies.