3D-printed Platform Research Articles

Metabolic engineering on a 3D-printed microfluidic platform: A new approach for modular co-metabolic pathways

Metabolic engineering of cell factories often requires extensive modification of host cellular machinery, leading to numerous challenges such as metabolic burden, intermediate metabolite toxicity, and inadequate endogenous fluxes. To overcome the limitations, we presented an innovative approach for metabolic engineering, by constructing modular biosynthetic pathways on a 3D-printed microfluidic platform. Several new techniques have been developed, including novel designs of chip configurations, effective methods for enzyme immobilization on printed resins, and proper ways to regenerate cofactors in redox reactions. As a proof of concept, we built xylose consumption and CO2 fixation pathways in the microfluidic chips and successfully demonstrated that the platform was able to convert xylose and enable the rapid growth of Saccharomyces cerevisiae, which otherwise will not grow with xylose as the only carbon source. Overall, the 3D-printed microfluidic platform presents a much simpler and more efficient cell-free strategy for developing modular, optimized biosynthetic pathways.

Novel 3D-Printed Microfluidic Magnetic Platform for Rapid DNA Isolation.

This study presents a novel miniaturized device as a 3D-printed microfluidic magnetic platform specifically designed to manipulate magnetic microparticles in a microfluidic chip for rapid deoxyribonucleic acid (DNA) isolation. The novel design enables the movement of the magnetic particles in the same or opposite directions with the flow or suspends them in continuous flow. A computational model was developed to assess the effectiveness of the magnetic manipulation of the particles. Superparamagnetic monodisperse silica particles synthesized in-house are utilized for the isolation of fish sperm DNA and human placenta DNA. It was demonstrated that the proposed platform can perform DNA isolation within 10 min with an isolation efficiency of 50% at optimum operating conditions.

Advanced 3D Electrospinning "Xspin" System: Fabrication of Bifiber Floating Oral Pharmaceutical Scaffolds for Controlled Drug Delivery.

Electrospinning has become a widely used and efficient method for manufacturing nanofibers from diverse polymers. This study introduces an advanced electrospinning technique, Xspin - a multi-functional 3D printing platform coupled with electrospinning system, integrating a customised 3D printhead, MaGIC - Multi-channeled and Guided Inner Controlling printheads. The Xspin system represents a cutting-edge fusion of electrospinning and 3D printing technologies within the realm of pharmaceutical sciences and biomaterials. This innovative platform excels in the production of novel fiber with various materials and allows for the creation of highly customized fiber structures, a capability hitherto unattainable through conventional electrospinning methodologies. By integrating the benefits of electrospinning with the precision of 3D printing, the Xspin system offers enhanced control over the scaffold morphology and drug release kinetics. Herein, we fabricated a model floating pharmaceutical dosage for the dual delivery of curcumin and ritonavir and thoroughly characterized the product. Fourier transform infrared (FTIR) spectroscopy demonstrated that curcumin chemically reacted with the polymer during the Xspin process. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the solid-state properties of the active pharmaceutical ingredient after Xspin processing. Scanning electron microscopy (SEM) revealed the surface morphology of the Xspin-produced fibers, confirming the presence of the bifiber structure. To optimize the quality and diameter control of the electrospun fibers, a design of experiment (DoE) approach based on quality by design (QbD) principles was utilized. The bifibers expanded to approximately 10-11 times their original size after freeze-drying and effectively entrapped 87% curcumin and 84% ritonavir. In vitro release studies demonstrated that the Xspin system released 35% more ritonavir than traditional pharmaceutical pills in 2 h, with curcumin showing complete release in pH 1.2 in 5 min, simulating stomach media. Furthermore, the absorption rate of curcumin was controlled by the characteristics of the linked polymer, which enables both drugs to be absorbed at the desired time. Additionally, multivariate statistical analyses (ANOVA, pareto chart, etc.) were conducted to gain better insights and understanding of the results such as discern statistical differences among the studied groups. Overall, the Xspin system shows significant potential for manufacturing nanofiber pharmaceutical dosages with precise drug release capabilities, offering new opportunities for controlled drug delivery applications.

A 3D-Printed Piezoelectric Microdevice for Human Energy Harvesting for Wearable Biosensors.

The human body is a source of multiple types of energy, such as mechanical, thermal and biochemical, which can be scavenged through appropriate technological means. Mechanical vibrations originating from contraction and expansion of the radial artery represent a reliable source of displacement to be picked up and exploited by a harvester. The continuous monitoring of physiological biomarkers is an essential part of the timely and accurate diagnosis of a disease with subsequent medical treatment, and wearable biosensors are increasingly utilized for biomedical data acquisition of important biomarkers. However, they rely on batteries and their replacement introduces a discontinuity in measured signals, which could be critical for the patients and also causes discomfort. In the present work, the research into a novel 3D-printed wearable energy harvesting platform for scavenging energy from arterial pulsations via a piezoelectric material is described. An elastic thermoplastic polyurethane (TPU) film, which forms an air chamber between the skin and the piezoelectric disc electrode, was introduced to provide better adsorption to the skin, prevent damage to the piezoelectric disc and electrically isolate components in the platform from the human body. Computational fluid dynamics in the framework of COMSOL Multiphysics 6.1 software was employed to perform a series of coupled time-varying simulations of the interaction among a number of associated physical phenomena. The mathematical model of the harvester was investigated computationally, and quantification of the output energy and power parameters was used for comparisons. A prototype wearable platform enclosure was designed and manufactured using fused filament fabrication (FFF). The influence of the piezoelectric disc material and its diameter on the electrical output were studied and various geometrical parameters of the enclosure and the TPU film were optimized based on theoretical and empirical data. Physiological data, such as interdependency between the harvester skin fit and voltage output, were obtained.

Occupational Therapy and Assistive Technology: Experience in Using 3D Printing and Open Source Platforms

Three-dimensional printing technology has evolved rapidly, being widely spread throughout the world and used in various fields such as design, engineering, medicine, and dentistry, among others. However, it is still little used in research and clinical practice in occupational therapy. A report is presented on the use of three-dimensional printing and open source platforms in clinical practice, based on experience in research and extension activity developed by the Laboratory for Research in Neuropediatrics, Technology and Inclusion (LINTI), which aims to provide an assistive product made in 3D printing to patients treated in the Supervised Internship in Occupational Therapy services that take place at the Specialized Rehabilitation Center (CER II). The actions are developed in four stages: 1- identification of the need; 2 - problem analysis and specification of the open source product;3 – 3D printing production; 4- user assistive product validation tests. This project has highlighted the possibility of creating functional, accessible assistive products, with desired aesthetics, and above all, with modification alternatives and adjustments for the user. 3D printing technology and open source platforms can be applicable and innovative tools in the practice of occupational therapists working in assistive technology.

Continuous production of bimetallic nanoparticles on carbon nanotubes based on 3D-printed microfluidics.

Nanoparticle-functionalized carbon nanotubes are promising in many research fields, especially in sensing, due to their intriguing performance in catalysis. However, these nanomaterials are mainly produced through batch processes under harsh conditions, thus encountering inherent limitations of low throughput and uncontrollable morphology of functional nanoparticles (NPs). In this work, we propose a method for high-yield and continuous production of bimetallic (Pt-Pd) NPs on multi-walled carbon nanotubes (MWCNTs) at room temperature through a custom 3D-printed microfluidic platform. A homogenous particle nucleation and growth environment could be created on the microfluidic platform that was equipped with two 3D-printed micromixers. Pt-Pd NPs loaded on MWCNTs were prepared in the microfluidic platform with high throughput and controlled size, dispersity and composition. The synthetic parameters for these nanocomposites were investigated to optimize their electrocatalytic performance. The optimized nanocomposites exhibited excellent electrocatalytic activity with exceptional sensitivity and wide detection range, superior to their counterparts prepared via conventional approaches. This method proposed here could be further adapted for manufacturing other catalyst support materials, opening more avenues for future large-scale production and catalytic investigation of functional nanomaterials.

Determination of Δ9-Tetrahydrocannabinol and Cannabidiol by Voltammetry using Low-Cost Screen-Printed Electrodic Platforms: A Significant Potential for Application in Clinical and Forensic Fields

Cannabis sativa has been utilized for centuries due to its psychoactive and therapeutic effects resulting from the presence of cannabinoids, which are exclusively found in plants of the Cannabis genus. The methods currently used by law enforcement and pharmaceutical industries to detect and measure cannabinoids include colorimetric testing, as well as instrumental methods such as HPLC and GC-MS. The aim of this work is to create a new method that can overcome the limitations of existing methods. To achieve this goal, a voltammetric method was developed using CV and LSV techniques. The method used a 3D-printed electrodic platform that was chemically modified with carbon paste and silver ink. The developed electrode was successful in detecting and measuring the amounts of Δ9-THC and CBD. The analytical parameters and average concentrations obtained were similar to those of popular commercial electrodes such as the platinum disk electrode and SPPE. The values for the limits of detection (LOD) and quantification (LOQ) were in the range of µmol L-1. The developed method and electrode show promise for detecting and quantifying Δ9-THC and CBD. The method was compared to the GC-MS technique, yielding relative error values ranging from 2.27% to 18.66%. A miniaturized, portable, versatile, and cost-effective method was developed with significant potential for clinical and forensic applications.

Additive-manufactured paper-PMMA hybrid microfluidic chip for simultaneous monitoring of creatinine and pH in artificial urine.

Nowadays, kidney dysfunction is a common health issue due to the modernized lifestyle. Even though medications are commercially available to treat kidney diseases, early diagnosis is crucial and challenging. Clinically, measuring urine creatinine and pH has gained significant interest as a way to diagnose kidney diseases early. In the present work, we attempted to develop a low-cost, robust, accurate and naked-eye colorimetric method to determine both creatinine levels and pH variations in artificial urine samples using a simple 3D-printed hybrid microfluidic device. Creatinine was detected by the incorporation of the traditional Jaffe test onto the hybrid paper-PMMA microfluidic device and pH (4-8) was measured by a simple anthocyanin test. Notably, the tests were established without employing any sophisticated or costly instrument clusters. The developed 3D-printed microfluidic probe showed a limit of detection (LOD) of 0.04 mM for creatinine over a concentration range of 1-10 mM, with a regression coefficient (R2) of 0.995 in laboratory conditions. Interestingly, the experimental data obtained with artificial urine exhibited a wide linear range from 0.1 mM to 5 mM under different pH values ranging from 4 to 8 in the presence of matrices commonly found in urine samples other than proteins, indicating the potential use of this method in pre-clinical analysis. Since the wide linear range of urine creatinine in artificial urine samples falls well below the clinically relevant concentrations in humans (0.07-0.27 mM), the developed lab-on-chip device is further suitable for clinical evaluation with proper ethical clearance. This 3D-printed hybrid microfluidic colorimetry-based creatinine detection and pH indicator platform can be beneficial in the healthcare sector due to the on-site testing capability, cost-effectiveness, ease of use, robustness, and instrument-free approach.

3D Printing of a Biomimetic Myotendinous Junction Assisted by Artificial Intelligence.

The myotendinous junction (MTJ) facilitates force transmission between muscle and tendon to produce joint movement. The complex microarchitecture and regional mechanical heterogeneity of the myotendinous junction pose major challenges in creating this interface in vitro. Engineering this junction in vitro is challenging due to substantial fabrication difficulties in creating scaffolds with intricate microarchitecture and stiffness heterogeneity to mimic the native muscle-tendon interface. To address the current challenges in creating the MTJ in vitro, digital light processing (DLP)-based 3D printing was used to fabricate poly(glycerol sebacate)acrylate (PGSA)-based muscle-tendon scaffolds with physiologically informed microstructure and mechanical properties. Local mechanical properties in various regions of the scaffold were tuned by adjusting the exposure time and light intensity used during the continuous DLP-based 3D printing process to match the mechanical properties present in distinct regions of native muscle-tendon tissue using printing parameters defined by an artificial intelligence-trained algorithm. To evaluate how the presence of zonal stiffness regions can affect the phenotype of a 3D-printed MTJ in vitro model, three 3D-printed PGSA-based scaffold conditions were investigated: (1) a scaffold with muscle-informed mechanical properties in its entirety without zonal stiffness regions, (2) a scaffold with one end possessing native muscle stiffness and the other end possessing native tendon stiffness, and (3) a scaffold with three distinct regions whose stiffness values correspond to those of muscle on one end of the scaffold, MTJ in the middle junction of the scaffold, and tendon on the other end of the scaffold. The scaffold containing regional mechanical heterogeneity most similar to the native MTJ (condition 3) was found to enhance the expression of MTJ-related markers compared to those without the presence of zonal stiffness regions. Overall, the DLP-based 3D printing platform and biomaterial system developed in this study could serve as a useful tool for mimicking the complexity of the native MTJ, which possesses inherent geometric and mechanical heterogeneity.

The 3D Printing of Nanocomposites for Wearable Biosensors: Recent Advances, Challenges, and Prospects.

Notably, 3D-printed flexible and wearable biosensors have immense potential to interact with the human body noninvasively for the real-time and continuous health monitoring of physiological parameters. This paper comprehensively reviews the progress in 3D-printed wearable biosensors. The review also explores the incorporation of nanocomposites in 3D printing for biosensors. A detailed analysis of various 3D printing processes for fabricating wearable biosensors is reported. Besides this, recent advances in various 3D-printed wearable biosensors platforms such as sweat sensors, glucose sensors, electrocardiography sensors, electroencephalography sensors, tactile sensors, wearable oximeters, tattoo sensors, and respiratory sensors are discussed. Furthermore, the challenges and prospects associated with 3D-printed wearable biosensors are presented. This review is an invaluable resource for engineers, researchers, and healthcare clinicians, providing insights into the advancements and capabilities of 3D printing in the wearable biosensor domain.

Fine Motor Training using Conventional Tools, 3D-printed Toys and Digital Platform

Early childhood muscle development is vital, especially for activities like pinch and grip, which require fine motor skills and eye coordination. Children with autism and Down syndrome often struggle with these activities, leading to rehabilitation programs using conventional tools. However, special needs children's limited attention span poses a challenge for trainers. This research aimed to address this issue by developing a training tool capturing and sustaining special needs children's attention, and analyzing their muscle activity with surface electromyography (sEMG). A comparison was made between conventional tools and 3D-printed toys with integrated audio and visual stimuli, extending to normal children and young adults using 3D-printed toys and a digital platform. sEMG signals from the flexor digitorum superficial muscle were recorded during fine motor training sessions. The findings revealed that the attention span of special needs children increased between 44% and 250% when using 3D-printed toys compared to conventional tools. Simultaneously, sEMG temporal analysis indicated lower mean amplitude for special needs children compared to their typically developed counterparts. Regarding the digital platform, it was observed that the muscle activity of typically developed children resembled that of those using 3D-printed toys when compared to young adults. In conclusion, the use of 3D-printed toys and digital platforms may offer additional advantages for fine motor skill training in children.

3D printing injectable microbeads using a composite liposomal ink for local treatment of peritoneal diseases

The peritoneal cavity offers an attractive administration route for challenging-to-treat diseases, such as peritoneal carcinomatosis, post-surgical adhesions, and peritoneal fibrosis. Achieving a uniform and prolonged drug distribution throughout the entire peritoneal space, though, is difficult due to high clearance rates, among others. To address such an unmet clinical need, alternative drug delivery approaches providing sustained drug release, reduced clearance rates, and a patient-centric strategy are required. Here, we describe the development of a 3D-printed composite platform for the sustained release of the tyrosine kinase inhibitor gefitinib (GEF), a small molecule drug with therapeutic applications for peritoneal metastasis and post-surgical adhesions. We present a robust method for the production of biodegradable liposome-loaded hydrogel microbeads that can overcome the pharmacokinetic limitations of small molecules with fast clearance rates, a current bottleneck for the intraperitoneal (IP) administration of these therapeutics. By means of an electromagnetic droplet printhead, we 3D printed microbeads employing an alginate-based ink loaded with GEF-containing multilamellar vesicles (MLVs). The sustained release of GEF from microbeads was demonstrated. In vitro studies on an immortalized human hepatic cancer cell line (Huh-7) proved concentration-dependent cell death. These findings demonstrate the potential of 3D-printed alginate microbeads containing liposomes for delivering small drug compounds into the peritoneum, overcoming previous limitations of IP drug delivery.Graphical abstract

Improving the performance and versatility of microfluidic thread electroanalytical devices by automated injection with electronic pipettes: a new and powerful 3D-printed analytical platform.

Microfluidic cotton thread-based electroanalytical devices (μTEDs) are analytical systems with attractive features such as spontaneous passive flow, low cost, minimal waste production, and good sensitivity. Currently, sample injection in µTEDs is performed by hand using manual micropipettes, which have drawbacks such as inconstant speed and position, dependence of skilled analysts, and need of physical effort of operator during prolonged times, leading to poor reproducibility and risk of strain injury. As an alternative to these inconveniences, we propose, for the first time, the use of electronic micropipettes to carry out automated injections in µTEDs. This new approach avoids all disadvantages of manual injections, while also improving the performance, experience, and versatility of µTEDs. The platform developed here is composed by three 3D-printed electrodes (detector) attached to a 3D-printed platform containing an adjustable holder that keeps the electronic pipette in the same x/y/z position. As a proof-of-concept, both injection modes (manual and electronic) were compared using three model analytes (nitrite, paracetamol, and 5-hydroxytryptophan) on µTED with amperometric detection. As result, improved analytical performance (limits of detection between 2.5- and 5-fold lower) was obtained when using electronic injections, as well as better repeatability/reproducibility and higher analytical frequencies. In addition, the determination of paracetamol in urine samples suggested better precision and accuracy for automated injection. Thus, electronic injection is a great advance and changes the state-of-art of µTEDs, mainly considering the use of more modern and versatile electronic pipettes (wider range of pre-programmed modes), which can lead to the development of even more automated systems.

3D-printed NIR-responsive bullets as multifunctional nanodrug platforms for image-guided local chemo-photothermal therapy

Multimodal cancer treatment that combines anticancer drug delivery with other therapeutic strategies, such as photothermal therapy, has shown enormous potential for biomedical applications. However, traditional nanoscale photothermal conversion agents require complicated synthesis processes and lack biosafety, detectability, and mechanical reinforcement ability in the hyperthermia platform. Here, we engineered near-infrared laser (NIR)-responsive bullets as multifunctional nanodrug platforms via a three-dimensional (3D) printing process as an image-guided versatile chemo-photothermal cancer treatment platform. This customizable platform not only serves as a container for anticancer nanodrugs but also possesses excellent radiopacity and high photothermal conversion efficiency, merging on-demand anticancer nanodrug release and hyperthermia effect. Benefiting from the combined chemo-photothermal therapy, the 3D-printed platform showed enhanced cytotoxicity to cancer cells in vitro. Furthermore, in vivo results confirmed effective on-demand nanodrug release and synergistic inhibition of tumor growth upon NIR laser irradiation. 3D-printed NIR-responsive bullets can synergistically enhance anticancer efficiency while evading potential clinical application risks, offering great potential for multimodal cancer therapies.

Design and Application of a New Visible Light-Curing 3D Printing Platform

In order to solve the safety problems that exist in traditional charging technology, a new visible light-curing 3D printing platform and energetic slurry formula were designed. Within them, the formula of light-curing slurry is 60.46% EA/PUA (prepolymer), 37.21% PETA/HDDA/BA (active diluent monomer), 0.47% CQ (visible light initiator), 0.93% DMT (curing accelerator), and 0.93% additive. The curing time of visible light-curing paste is 7.5 s, the viscosity is 22 6 mPa·s, the curing hardness is 2 H, the gel rate is 96.67%, the shrinkage rate is 98.35%, and the curing depth is 9.41 mm. The optimal formulation of energetic slurry is 20% visible light-curing slurry, 57.72% AP, 15.28% Al and 7% RDX. The 3D printing energetic powder column has a smooth surface, uniform filler distribution, a flat surface, no protrusions or other defects, and good matching. The average burning rate is 1.165 mm·s−1, the combustion is stable, and the maximum burning light intensity is 2.053 cd.

Low-rate smartphone videoscopy for microsecond luminescence lifetime imaging with machine learning.

Time-resolved techniques have been widely used in time-gated and luminescence lifetime imaging. However, traditional time-resolved systems require expensive lab equipment such as high-speed excitation sources and detectors or complicated mechanical choppers to achieve high repetition rates. Here, we present a cost-effective and miniaturized smartphone lifetime imaging system integrated with a pulsed ultraviolet (UV) light-emitting diode (LED) for 2D luminescence lifetime imaging using a videoscopy-based virtual chopper (V-chopper) mechanism combined with machine learning. The V-chopper method generates a series of time-delayed images between excitation pulses and smartphone gating so that the luminescence lifetime can be measured at each pixel using a relatively low acquisition frame rate (e.g. 30 frames per second [fps]) without the need for excitation synchronization. Europium (Eu) complex dyes with different luminescent lifetimes ranging from microseconds to seconds were used to demonstrate and evaluate the principle of V-chopper on a 3D-printed smartphone microscopy platform. A convolutional neural network (CNN) model was developed to automatically distinguish the gated images in different decay cycles with an accuracy of >99.5%. The current smartphone V-chopper system can detect lifetime down to ∼75 µs utilizing the default phase shift between the smartphone video rate and excitation pulses and in principle can detect much shorter lifetimes by accurately programming the time delay. This V-chopper methodology has eliminated the need for the expensive and complicated instruments used in traditional time-resolved detection and can greatly expand the applications of time-resolved lifetime technologies.

Flexible Allyl-Modified Gelatin Photoclick Resin Tailored for Volumetric Bioprinting of Matrices for Soft Tissue Engineering.

Volumetric bioprinting (VBP) is a light-based 3D printing platform, which recently prompted a paradigm shift for additive manufacturing (AM) techniques considering its capability to enable the fabrication of complex cell-laden geometries in tens of seconds with high spatiotemporal control and pattern accuracy. A flexible allyl-modified gelatin (gelAGE)-based photoclick resin is developed in this study to fabricate matrices with exceptionally soft polymer networks (0.2-1.0kPa). The gelAGE-based resin formulations are designed to exploit the fast thiol-ene crosslinking in combination with a four-arm thiolated polyethylene glycol (PEG4SH) in the presence of a photoinitiator. The flexibility of the gelAGE biomaterial platform allows one to tailor its concentration spanning from 2.75% to 6% and to vary the allyl to thiol ratio without hampering the photocrosslinking efficiency. The thiol-ene crosslinking enables the production of viable cell-material constructs with a high throughput in tens of seconds. The suitability of the gelAGE-based resins is demonstrated by adipogenic differentiation of adipose-derived stromal cells (ASC) after VBP and by the printing of more fragile adipocytes as a proof-of-concept. Taken together, this study introduces a soft photoclick resin which paves the way for volumetric printing applications toward soft tissue engineering.

Scanning Electron Microscopy and EDX Spectroscopy of Commercial Swabs Used for COVID-19 Lateral Flow Testing.

The chemical composition of COVID test swabs has not been examined beyond the manufacturer's datasheets. The unprecedented demand for swabs to conduct rapid lateral flow tests and nucleic acid amplification tests led to mass production, including 3D printing platforms. Manufacturing impurities could be present in the swabs and, if so, could pose a risk to human health. We used scanning electron microscopy and energy dispersive X-ray (EDX) spectroscopy to examine the ultrastructure of seven assorted brands of COVID test swabs and to identify and quantify their chemical elements. We detected eight unexpected elements, including transition metals, such as titanium and zirconium, the metalloid silicon, as well as post-transition metals aluminium and gallium, and the non-metal elements sulphur and fluorine. Some of the elements were detected as trace amounts, but for others, the amount was close to reported toxicological thresholds for inhalation routes. Experimental studies have shown that the detrimental effects of unexpected chemical elements include moderate to severe inflammatory states in the exposed epithelium as well as proliferative changes. Given the massive testing still being used in the context of the COVID pandemic, we urge caution in continuing to recommend repeated and frequent testing, particularly of healthy, non-symptomatic, individuals.

3D-Printed ferromagnetic Liquid Crystal Elastomer with Programmed Dual-Anisotropy And Multi-Responsiveness.

Liquid crystal elastomers (LCE) and magnetic soft materials are promising active materials in many emerging fields, such as soft robotics. Despite the high demand for developing active materials that combine the advantages of LCE and magnetic actuation, the lack of independent programming of the LCE nematic order and magnetization in a single material still hinders the desired multi-responsiveness. In this study, we developed a ferromagnetic LCE (magLCE) ink with nematic order and magnetization that can be independently programmed to be anisotropic, referred to as dual anisotropy, via a customized 3D printing platform. The magLCE ink was fabricated by dispersing ferromagnetic micro-particles in the LCE matrix, and a 3D printing platform was created by integrating a magnet with 3-DoF motion into an extrusion-based 3D printer. In addition to magnetic fields, magLCEs can also be actuated by heating sources (either environmental heating or photo-heating of the embedded ferromagnetic microparticles) with a high energy density and tunable actuation temperature. We demonstrated a programmed magLCE strip robot with enhanced adaptability to complex environments (different terrains, magnetic fields, and temperatures) using a multi-actuation strategy. The magLCE also has potential applications in mechanical memory, as demonstrated by the multi-stable mechanical metastructure array with remote writability and stable memory. This article is protected by copyright. All rights reserved.

Cu-C3N4 nanoenzyme-based freezing-dried bioactive capsule integrated with 3D-printed smartphone platform for visual detection of organophosphorus pesticides paraoxon in scallion

Rapid detection of pesticide residues in vegetables has recently attracted much attention. Herein, a Cu-modified graphitic carbon nitride nanomaterial (Cu-C3N4) with peroxidase (POD)-like property was synthesized to construct an enzyme-based colorimetric sensing platform for the detection of organophosphorus pesticides paraoxon. Cu-C3N4 could catalyze H2O2 produced by reaction of acetylcholine with acetylcholinesterase and choline oxidase, and then further oxidized 3,3,5,5-tetramethylbenzidine (TMB) to produce a blue colored product. Presence of organophosphorus pesticide paraoxon (PA) restrained the activity of acetylcholinesterase AChE, triggering a remarkably decreased amount of H2O2 towards TMB oxidation, which led to the inhibition of oxidation reaction. After that, the reaction solutions were freeze-dried in a portable bioactive capsule with addition of trehalose as stabilizer for improved enzymes activities. On the basis of the variation in gray-scale values of blue colored TMB solutions using an application, a smartphone-based 3D printing platform was obtained with a linear range from 100 to 33,000 nM (R2 =0.994) and a detection limit of 13 nM (3σ/k). This smartphone-based 3D-printed colorimetric platform combined with a bioactive capsule offers a novel approach with the potential for rapid detection of PA in vegetables.