3D Structure Research Articles

Synthesis and electrochemical properties of two cobalt(II) and nickel(II) metal-organic frameworks for excellent performance supercapacitors

Two novel metal-organic frameworks, [Co(HNTB)(bif)]·3H2O·DMA (1) and [(Ni2(μ2O)(HNTB)2(bif)2]·2H2O·2H3O·2DMA (2), were obtained with a tripod-type carboxylic ligand (4,4′,4″-Nitrilotrisbenzoic acid, H3NTB) and a rigid N-donor ligand (2,7-bis(1-imidazoly)fluorene, bif) by solvothermal method. Complex 1 exhibits a 2D layered structure and 2 is a 3D microporous structure with an anionic skeleton. Significantly, their electrochemical tests show that both of them own excellent capacitive performance. Complex 1 has a relatively high specific capacitance (301.2 F g−1 at 1 A g−1) with favorable cycling durability (retained 73.2 % over 3000 cycles). Complex 2 presents a high specific capacitance (329.6 F g−1 at 1 A g−1) with a relatively poor cycling durability (retained 58.9 % over 3000 cycles). Additionally, complex 1 // activates carbon (AC) as an asymmetrical ultra-capacitor exhibits a maximum energy density of 20.9 Wh kg−1 at 800.0 W kg−1 and a high cycle stability (retained 89.2 % over 8000 cycles). Complex 2 // AC owns an energy density of 19.3 Wh kg−1 at 750.0 W kg−1 and a satisfactory cycle stability (retained 88.6 % over 8000 cycles).

A Flexible Hierarchical Framework for Implicit 3D Characterization of Bionic Devices.

In practical applications, integrating three-dimensional models of bionic devices with simulation systems can predict their behavior and performance under various operating conditions, providing a basis for subsequent engineering optimization and improvements. This study proposes a framework for characterizing three-dimensional models of objects, focusing on extracting 3D structures and generating high-quality 3D models. The core concept involves obtaining the density output of the model from multiple images to enable adaptive boundary surface detection. The framework employs a hierarchical octree structure to partition the 3D space based on surface and geometric complexity. This approach includes recursive encoding and decoding of the octree structure and surface geometry, ultimately leading to the reconstruction of the 3D model. The framework has been validated through a series of experiments, yielding positive results.

Three-dimensional reconstruction of insect chemosensory sensillum

The olfactory system is involved in food and mate recognition in insects. However, 3D structures of chemosensory sensilla in insects are unexplored yet. Here, the internal structures of an olfactory sensillum on the antenna of the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), one of the most important rice pests, are examined and imaged using focused ion beam scanning electron microscopy. Based on these images, a 3D structure is reconstructed in this study. We find that the trichoid olfactory sensillum possesses a multiporous wall encircling a lumen with one sensory cell. Besides, there are three accessory cells (ACs) and a glia cell with different cell contents surrounding the sensory cell. The abundant tubular membrane structures in the tormogen cell suggest its role in secreting proteins like odorant binding proteins into the receptor lymph, while three auxiliary cells with simpler cellular content closely enfold the sensory cell, probably to prevent leaking of the receptor lymph into the surrounding epidermis. In the sensory cell, the microtubules and two tandem basal bodies at the base of the microtubules are also reconstructed. They are considered as a propulsive engine to ensure dendrite vibration or spinning in the receptor lymph, so that the proteins and odorant molecules move faster in the receptor lymph, which improves recognition of environmental odors and enables the insect to immediately respond to this information.

Structures of the Varicella Zoster Virus Glycoprotein E and Epitope Mapping of Vaccine-Elicited Antibodies.

Background: Varicella zoster virus (VZV) is the causative agent for chickenpox and herpes zoster (HZ, shingles). HZ is a debilitating disease affecting elderly and immunocompromised populations. Glycoprotein E (gE) is indispensable for viral replication and cell-to-cell spread and is the primary target for anti-VZV antibodies. Importantly, gE is the sole antigen in Shingrix, a highly efficacious, AS01B-adjuvanted vaccine approved in multiple countries for the prevention of HZ, yet the three-dimensional (3D) structure of gE remains elusive. Objectives: We sought to determine the structure of VZV gE and to understand in detail its interactions with neutralizing antibodies. Methods: We used X-ray crystallography and cryo-electron microscopy to elucidate structures of gE bound by recombinant Fabs of antibodies previously elicited through vaccination with Zostavax, a live, attenuated vaccine. Results: The 3D structures resolve distinct central and C-terminal antigenic domains, presenting an array of diverse conformational epitopes. The central domain has two beta-sheets and two alpha helices, including an IgG-like fold. The C-terminal domain exhibits 3 beta-sheets and an Ig-like fold and high structural similarity to HSV1 gE. Conclusions: gE from VZV-infected cells elicits a human antibody response with a preference for the gI binding domain of gE. These results yield insights to VZV gE structure and immunogenicity, provide a framework for future studies, and may guide the design of additional herpesvirus vaccine antigens. Teaser: Structures of varicella zoster virus glycoprotein E reveal distinct antigenic domains and define epitopes for vaccine-elicited human antibodies.

Mechanical and Biological Characterization of Ionic and Photo-Crosslinking Effects on Gelatin-Based Hydrogel for Cartilage Tissue Engineering Applications.

Articular cartilage degeneration poses a significant public health challenge; techniques such as 3D bioprinting are being explored for its regeneration in vitro. Gelatin-based hydrogels represent one of the most promising biopolymers used in cartilage tissue engineering, especially for its collagen composition and tunable mechanical properties. However, there are no standard protocols that define process parameters such as the crosslinking method to apply. To this aim, a reproducible study was conducted for exploring the influence of different crosslinking methods on 3D bioprinted gelatin structures. This study assessed mechanical properties and cell viability in relation to various crosslinking techniques, revealing promising results particularly for dual (photo + ionic) crosslinking methods, which achieved high cell viability and tunable stiffness. These findings offer new insights into the effects of crosslinking methods on 3D bioprinted gelatin for cartilage applications. For example, ionic and photo-crosslinking methods provide softer materials, with photo-crosslinking supporting cell stretching and diffusion, while ionic crosslinking preserves a spherical stem cell morphology. On the other hand, dual crosslinking provides a stiffer, optimized solution for creating stable cartilage-like constructs. The results of this study offer a new perspective on the standardization of gelatin for cartilage bioprinting, bridging the gap between research and clinical applications.

A Multi-Electrode Array Platform for Modeling Epilepsy Using Human Pluripotent Stem Cell-Derived Brain Assembloids.

Human brain organoids are three-dimensional (3D) structures derived from human pluripotent stem cells (hPSCs) that recapitulateaspects of fetal brain development. The fusion of dorsal with ventral regionally specified brain organoids in vitro generates assembloids, which have functionally integrated microcircuits with excitatory and inhibitory neurons. Due to their structural complexity and diverse population of neurons, assembloids have become a useful in vitro tool for studying aberrant network activity. Multi-electrode array (MEA) recordings serve as a method for capturing electrical field potentials, spikes, and longitudinal network dynamics from a population of neurons without compromising cell membrane integrity. However, adhering assembloids onto the electrodes for long-term recordings can be challenging due to their large size and limited contact surface area with the electrodes. Here, we demonstrate a method to plate assembloids onto MEA plates for recording electrophysiological activity over a 2-month span. Although the current protocol utilizes human cortical organoids, it can be broadly adapted to organoids differentiated to model other brain regions. This protocol establishes a robust, longitudinal, electrophysiological assay for studying the development of a neuronal network, and this platform has the potential to be used in drug screening for therapeutic development in epilepsy.

Integration of scHi-C and scRNA-seq data defines distinct 3D-regulated and biological-context dependent cell subpopulations

An integration of 3D chromatin structure and gene expression at single-cell resolution has yet been demonstrated. Here, we develop a computational method, a multiomic data integration (MUDI) algorithm, which integrates scHi-C and scRNA-seq data to precisely define the 3D-regulated and biological-context dependent cell subpopulations or topologically integrated subpopulations (TISPs). We demonstrate its algorithmic utility on the publicly available and newly generated scHi-C and scRNA-seq data. We then test and apply MUDI in a breast cancer cell model system to demonstrate its biological-context dependent utility. We find the newly defined topologically conserved associating domain (CAD) is the characteristic single-cell 3D chromatin structure and better characterizes chromatin domains in single-cell resolution. We further identify 20 TISPs uniquely characterizing 3D-regulated breast cancer cellular states. We reveal two of TISPs are remarkably resemble to high cycling breast cancer persister cells and chromatin modifying enzymes might be functional regulators to drive the alteration of the 3D chromatin structures. Our comprehensive integration of scHi-C and scRNA-seq data in cancer cells at single-cell resolution provides mechanistic insights into 3D-regulated heterogeneity of developing drug-tolerant cancer cells.

Chirality-Mediated 1D-to-2D Phase Transition in Hybrid Lead Halide Perovskites.

Dimensionality engineering plays a pivotal role in optimizing the performance, ensuring long-term stability, and expanding the versatile applications of lead halide perovskites (LHPs). Currently, the manipulation of LHP dimensions primarily occurs during the synthesis stage, a procedure hampered by constraints, including synthetic complexity and irreversibility. This investigation successfully achieved a transition from one-dimensional (1D) to two-dimensional (2D) structures in chiral LHPs by applying hydrostatic pressure. Remarkably, this pressure-induced transition in dimensionality is absent in the racemic analogue due to the staggered arrangement of inorganic chains and the elevated steric hindrance posed by the organic cations. Notably, the hydrogen bonding between organic cations and the inorganic framework adopts a symmetrical arrangement in the racemic system but a helical configuration along the 1D chain direction in the chiral counterparts. This distinct helical arrangement induces a consequential distortion in the inorganic moiety, resulting in the emergence of a spin-polarized Rashba-Dresselhaus texture that explains the chirality's electronic spin origin. Furthermore, both experimental and density functional theory calculation results demonstrate that the 1D-to-2D phase transition in chiral halide perovskites can induce significant modifications in the electronic structures and associated optical emissions. In summary, the findings unveil novel avenues for manipulating optoelectronic properties in chiral perovskites through dimensionality engineering.

Opportunities at the Intersection of 3D Printed Polymers and Pyrolysis for the Microfabrication of Carbon-Based Energy Materials.

In an era marked by a growing demand for sustainable and high-performance materials, the convergence of additive manufacturing (AM), also known as 3D printing, and the thermal treatment, or pyrolysis, of polymers to form high surface area hierarchically structured carbon materials stands poised to catalyze transformative advancements across a spectrum of electrification and energy storage applications. Designing 3D printed polymers using low-cost resins specifically for conversion to high performance carbon structures via post-printing thermal treatments overcomes the challenges of 3D printing pure carbon directly due to the inability of pure carbon to be polymerized, melted, or sintered under ambient conditions. In this perspective, we outline the current state of AM methods that have been used in combination with pyrolysis to generate 3D carbon structures and highlight promising systems to explore further. As part of this endeavor, we discuss the effects of 3D printed polymer chemistry composition, additives, and pyrolysis conditions on resulting 3D pyrolytic carbon properties. Furthermore, we demonstrate the viability of combining continuous liquid interface production (CLIP) vat photopolymerization with pyrolysis as a promising avenue for producing 3D pyrolytic carbon lattice structures with 15 μm feature resolution, paving way for 3D carbon-based sustainable energy applications.

Laser solid-phase synthesis of graphene shell-encapsulated high-entropy alloy nanoparticles

Rapid synthesis of high-entropy alloy nanoparticles (HEA NPs) offers new opportunities to develop functional materials in widespread applications. Although some methods have successfully produced HEA NPs, these methods generally require rigorous conditions such as high pressure, high temperature, restricted atmosphere, and limited substrates, which impede practical viability. In this work, we report laser solid-phase synthesis of CrMnFeCoNi nanoparticles by laser irradiation of mixed metal precursors on a laser-induced graphene (LIG) support with a 3D porous structure. The CrMnFeCoNi nanoparticles are embraced by several graphene layers, forming graphene shell-encapsulated HEA nanoparticles. The mechanisms of the laser solid-phase synthesis of HEA NPs on LIG supports are investigated through theoretical simulation and experimental observations, in consideration of mixed metal precursor adsorption, thermal decomposition, reduction through electrons from laser-induced thermionic emission, and liquid beads splitting. The production rate reaches up to 30 g/h under the current laser setup. The laser-synthesized graphene shell-encapsulated CrMnFeCoNi NPs loaded on LIG-coated carbon paper are used directly as 3D binder-free integrated electrodes and exhibited excellent electrocatalytic activity towards oxygen evolution reaction with an overpotential of 293 mV at the current density of 10 mA/cm2 and exceptional stability over 428 h in alkaline media, outperforming the commercial RuO2 catalyst and the relevant catalysts reported by other methods. This work also demonstrates the versatility of this technique through the successful synthesis of CrMnFeCoNi oxide, sulfide, and phosphide nanoparticles.

A 3D network-structured gel polymer electrolyte with soluble starch for enhanced quasi-solid-state lithium-sulfur batteries

The polysulfide shuttling effect and safety concerns associated with liquid electrolytes impede the commercialization of lithium-sulfur (Li-S) batteries. We report a novel gel polymer electrolyte (GPE) denoted as "PTPHS" prepared via facile ultraviolet polymerization of pentaerythritol tetrakis (3-mercaptopropionate) (PETT) and pentaerythritol tetraacrylate (PETEA) with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the polymer matrix. Soluble starch (SST) is incorporated as an interacting filler to construct a 3D network structure with intermolecular hydrogen bonds. This unique architecture not only ensures high ionic conductivity and mechanical robustness but also effectively mitigates the polysulfide shuttling effect, thereby improving cycling stability. The PTPHS-based Li-S cell exhibits stable cycling over 150 cycles at 0.2 C with 87.6 % capacity retention. This strategy provides insights into material development and structural design of GPEs for high-performance quasi-solid-state Li-S batteries.

Enhanced solar-powered H2 production from water splitting and sustainable wastewater treatment using interface-engineered ZnIn2S4/TiO2/Ti3C2 S-scheme heterocatalyst

Developing efficient photocatalysts that can degrade persistent antibiotics in water bodies and generate clean H2 through water splitting is crucial for environmental and energy sustainability. This study introduces an advanced hierarchical ZnIn2S4/TiO2/Ti3C2 (ZIS/TO/TC) heterocatalyst for the efficient removal of amoxicillin (AXC) from wastewater and the production of H2 through water reduction process under simulated solar illumination. The ZIS/TO/TC hybrids were fabricated via an in situ hydrothermal process, resulting in a hierarchical 3D structure that capitalizes on the complementary properties of each component. The design of the S-scheme heterojunction significantly enhances charge separation and transfer efficiency, offering improvements over traditional type-II or Z-scheme mechanisms. Notably, the optimized ZIS10/TO/TC hybrid catalyst demonstrated remarkable activity, achieving 100 % AXC degradation and excellent mineralization within 90 min, along with an H2 production rate of 4104 μmol h−1 g−1, significantly outperforming the individual components and exceeding previously reported efficiencies. The outstanding performance of the ZIS10/TO/TC hybrid is attributed to its enhanced light absorption properties, synergistic interactions among the ZIS, TO, and TC MXene, and the efficient S-scheme charge transfer mechanism, which facilitates effective charge separation and transfer while preserving the strong reducing and oxidizing capabilities of the components. Additionally, the ZIS10/TO/TC hybrid exhibited excellent stability over multiple photocatalytic tests, emphasizing its potential for practical applications. Therefore, this research demonstrates an advanced and highly efficient hybrid photocatalyst that offers a promising and sustainable solution for both integrated water treatment and renewable energy generation.

A novel Zn(II) coordination polymer based on viologen: Photochromism, photocontrolled luminescence, ammonia vapor sensing, and luminescent sensing

A novel Zn(II) coordination polymer, {[Zn4(BTEC)3][(3-BCBPY)2]·5H2O}n (compound 1), was synthesized based on viologen ligand (3-BCBPY·2Cl = 1,1′-bis(3-cyanobenzyl)-4,4′-bipyridinium chloride), benzoic acid (H4BTEC = 1,2,4,5-benzenetetracarboxylic acid) and ZnCl2. Single crystal X-ray diffraction analysis revealed that the Zn(II) ions are bridged by BTEC4− anions, giving rise to a 3D structure, with the 3-BCBPY2+ cations occupying the pores within the channels of compound 1. This compound displays photoactivity, undergoing significant color transformations under ultraviolet light irradiation. Furthermore, to gain a deeper theoretical understanding of the color-changing behavior of compound 1, time-dependent density functional theory (TDDFT) was employed. Additionally, compound 1 demonstrates ammonia vapor sensing capabilities, along with intriguing light-modulated luminescence properties. Notably, it also exhibits significant sensing abilities for Fe3+ and Cr2O72− ions, even at low concentrations (10−5 M). This compound not only showcases its applications in the realms of photochromism, but also explores its potential in ammonia vapor detection and ion sensing.

Structure-based validation of recombinant light-harvesting complex II.

Light-harvesting complex II (LHCII) captures sunlight and dissipates excess energy to drive photosynthesis. To elucidate this mechanism, the individual optical properties of pigments in the LHCII protein must be identified. In vitro reconstitution with apoproteins synthesized by Escherichia coli and pigment-lipid mixtures from natural sources is an effective approach; however, the local environment surrounding each pigment within reconstituted LHCII (rLHCII) has only been indirectly estimated using spectroscopic and biochemical methods. Here, we used cryo-electron microscopy to determine the 3D structure of the rLHCII trimer and found that rLHCII exhibited a structure that was virtually identical to that of native LHCII, with a few exceptions: some C-terminal amino acids were not visible, likely due to aggregation of the His-tags; a carotenoid at the V1 site was not visible; and at site 614 showed mixed occupancy by both chlorophyll a and b molecules. Our observations confirmed the applicability of the in vitro reconstitution technique.

In silico Discovery of Leptukalins, The New Potassium Channel Blockers from the Iranian Scorpion, Hemiscorpius Lepturus.

Blocking Kv 1.2 and Kv 1.3 potassium channels using scorpion venom- derived toxins holds potential therapeutic value. These channels are implicated in autoimmune diseases such as neurodegenerative diseases, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes. The present work aims at the discovery and in silico activity analysis of potassium channel blockers (KTxs) from the cDNA library derived from the venom gland of Iranian scorpion Hemiscorpius lepturus (H. lepturus). The sequence regarding potassium channel blockers were extracted based on Gene Ontology for H. lepturus venom gland. Homology analyses, superfamily, family, and evolutionary signatures of H. lepturus KTxs (H.L KTxs) were determined by using BLASTP, COBALT, PROSITE, and InterPro servers. The predicted 3D structures of H.L KTxs were superimposed against their homologs to predict structure activity relationship. Molecular docking analysis was also performed to predict the binding affinity of H.L KTxs to Kv 1.2 and Kv 1.3 channels. Finally, the toxicity was predicted. Seven H.L KTxs, designated as Leptukalin, were extracted from the cDNA library of H. lepturus venom gland. Homology analyses proved that they can act as potassium channel blockers and they belong to the superfamily and family of Scorpion Toxin-like and Short-chain scorpion toxins, respectively. Structural alignment results confirmed the activity of H.L KTxs. Binding affinity of all H.L KTxs to Kv 1.2 and Kv 1.3 channels ranged from -4.4 to -5.5 and -4 to -5.7 Kcal/mol, respectively. In silico toxicity assay showed that Leptukalin 3, Leptukalin 5, and Leptukalin 7 were non-toxic. Three non-toxic KTxs, Leptukalin 3, 5, and 7, were successfully discovered from the cDNA library of H. lepturus venom gland. Gathering all data together, the discovered peptides are promising potassium channel blockers. Accordingly, Leptukalin 3, 5, and 7 could be suggested for complementary in vitro studies and mouse model of autoimmune diseases.

Genetic profile of progressive myoclonic epilepsy in Mali reveals novel findings.

Progressive myoclonic epilepsy (PME) is a group of neurological disorders characterized by recurrent myoclonic seizures with progressive neurological deterioration. We investigated the genetics of three unrelated patients with PME from Mali, a country in sub-Saharan Africa highly underrepresented in genetic and genomic research. Participants were carefully examined and phenotyped. DNA was obtained for genetic analysis including whole exome sequencing (WES). In silico prediction tools and ACMG criteria were used to assess the deleteriousness of putative candidate variants. Pedigree analysis suggests autosomal recessive inheritance patterns for one family and sporadic forms of PME for the two other cases. WES identified novel homozygous missense variants in all the three patients, one each for NHLRC1, EPM2A, and NEU1. The sequence variants segregated with PME in each family and in silico studies including protein 3D structures, CADD scores and ACMG criteria suggested that they were damaging. PME is a group of clinically heterogeneous neurological disorders. Most reported cases in the literature are from European background with only a few cases described in North Africa. We report here novel pathogenic variants in three different genes causing PME phenotypes in three unrelated Malian patients, suggesting that genetic studies of underrepresented populations may expand the genetic epidemiology of PME. These findings also emphasize the need for inclusive genetic research to ensure a more targeted diagnostic and therapeutic approaches for diverse patient populations.

GRNAde: A Geometric Deep Learning Pipeline for 3D RNA Inverse Design.

Fundamental to the diverse biological functions of RNA are its 3D structure and conformational flexibility, which enable single sequences to adopt a variety of distinct 3D states. Currently, computational RNA design tasks are often posed as inverse problems, where sequences are designed based on adopting a single desired secondary structure without considering 3D geometry and conformational diversity. In this tutorial, we present gRNAde, a geometric RNA design pipeline operating on sets of 3D RNA backbone structures to design sequences that explicitly account for RNA 3D structure and dynamics. gRNAde is a graph neural network that uses an SE (3) equivariant encoder-decoder framework for generating RNA sequences conditioned on backbone structures where the identities of the bases are unknown. We demonstrate the utility of gRNAde for fixed-backbone re-design of existing RNA structures of interest from the PDB, including riboswitches, aptamers, and ribozymes. gRNAde is more accurate in terms of native sequence recovery while being significantly faster compared to existing physics-based tools for 3D RNA inverse design, such as Rosetta.

Small molecular weight alginate gel porogen for the 3D bioprinting of microvasculature.

In order to recreate the complexity of human organs, the field of tissue engineering and regenerative medicine has been focusing on methods to build organs from the bottom up by assembling distinct small functional units consisting of a biomaterial and cells. This bottom-up engineering requires bioinks that can be assembled by 3D bioprinting and that permit fast vascularization of the construct to ensure survival of embedded cells. To this end, a small molecular weight alginate (SMWA) gel porogen is presented herein. Alginate is a biocompatible biomaterial, which can be easily converted into small porogen gels with the procedure reported in this article. The SMWA porogen is mixed with photo-crosslinkable hydrogels and leached from the hydrogel post-crosslinking to increase porosity and facilitate vascularization. As a proof of concept, this system is tested with the commonly used biomaterial Gelatin Methacryloyl (GelMA). The SMWA porogen-GelMA blend is proven to be bioprintable. Incubating the blend for 20min in a low concentration phosphate buffered saline and sodium citrate solution significantly reduces the remaining porogen in the hydrogel . The intent to completely leach the porogen from the hydrogel was abandoned, as longer incubation times and higher concentrations of phosphate and citrate were detrimental to endothelial proliferation. Nonetheless, even with remnants of the porogen left in the hydrogel, the created porosity significantly improves viability, growth factor signaling, vasculogenesis, and angiogenesis in 3D bioprinted structures. This article concludes that the usage of the SMWA porogen can improve the assembly of microvasculature in 3D bioprinted structures. This technology can benefit the bottom-up assembly of large scaffolds with high cell density through 3D bioprinting by improving cell viability and allowing faster vascularization.

Naphthalenedisulfonate-based Cd(II) CPs as fluorescent sensors for turn-on and red-shift sensing of tryptophan

Tryptophan (Trp) is one of the essential amino acids in human body, which is important for human health. Therefore, convenient strategies for the detection of Trp are very significant. Coordination polymers (CPs) have presented great importance as fluorescent sensors in recent years. Herein, two Cd(II) CPs were synthesized as fluorescent sensors for turn-on and red-shift sensing of tryptophan, namely, {[Cd(1,4-bbix)2(1,5-NDS)]·(H2O)2}n (1) and {[Cd(bmbp)2(H2O)2]·(1,5NDS)(H2O)4}n (2), (1,5-NDS = 1,5-naphthalenedisulfonate, 1,4-bbix = 1,4-bis(benzimidazol-1-yl-methyl)benzene, bmbp = 4,4′-bis(2-methylimidazole-1-yl-methyl)biphenyl). 1 shows a three-dimensional (3D) structure with 6-connected pcu topology. 2 shows a 1D chain, which is connected by hydrogen-bonds to form the 3D supramolecular structure. Both CPs can effectively detect Trp via fluorescence enhancement and red-shift in aqueous solution with the limits of detection being 1.11 μM and 0.69 μM for 1 and 2, respectively. Two CPs also can be applied for the detection of Trp in milk with good sensitivity. The sensing mechanisms toward Trp were investigated via experimental and theoretical calculation methods. The test films were prepared for the visual detection of Trp.

Effect of magnesium and calcium ions on the strength and biofunctionality of GelMA/SAMA composite hydrogels.

Natural polymers and synthetic polymers have been extensively studied as scaffold materials, with the former offering advantages such as biocompatibility, biodegradability, and structural similarity to the natural extracellular matrix (ECM). However, the use of natural polymers in extrusion-based 3D printing has been limited by their poor mechanical properties and challenging rheological properties. In this study, gelatin and sodium alginate were utilized as scaffold materials, with the addition of Ca2+ and Mg2+ components to enhance their physical and chemical properties, and influence early cell behavior. Subsequently, these materials were fabricated into scaffolds using 3D printing. Our results demonstrated that the addition of Ca2+ and Mg2+ could improve the compactness of the 3D network structure, mechanical strength, swelling properties and degradation properties of methacrylated gelatin/methacrylated sodium alginate (GelMA/SAMA) composite hydrogel. In vitro cell tests revealed that the GelMA/SAMA composite hydrogel exhibited negligible cytotoxicity and promoted early cell viability, particularly with the higher concentration of Mg2+ in the material. Notably, the extrusion 3D printing process successfully produced GelMA/SAMA scaffolds. These results collectively indicate that GelMA/SAMA composite scaffolds hold promise as potential biomaterials for tissue engineering applications.