Table of contents

The ability to seamlessly integrate functional materials into three-dimensional (3D) constructs has been of significant interest, as it can enable the creation of multifunctional devices. Such integration can be achieved with a multiscale, multi-material 3D printing strategy. This technology has enabled the creation of unique devices such as personalized tissue regenerative scaffolds, biomedical implants, 3D electronic devices, and bionic constructs which are challenging to realize with conventional manufacturing processes. In particular, the incorporation of nanomaterials into 3D printed devices can endow a wide range of constructs with tailorable mechanical, chemical, and electrical functionalities. This review highlights the advances and unique possibilities in the fabrication of novel electronic, biomedical, and bioelectronic devices that are realized by the synergistic integration of nanomaterials with 3D printing technologies.

The development of three-dimensional (3D) scaffolds with physical and chemical topological cues at the macro-, micro-, and nanometer scale is urgently needed for successful tissue engineering applications. 3D scaffolds can be manufactured by a wide variety of techniques. Electrospinning technology has emerged as a powerful manufacturing technique to produce non-woven nanofibrous scaffolds with very interesting features for tissue engineering products. However, electrospun scaffolds have some inherent limitations that compromise the regeneration of thick and complex tissues. By integrating electrospinning and other fabrication technologies, multifunctional 3D fibrous assemblies with micro/nanotopographical features can be created. The proper combination of techniques leads to materials with nano and macro-structure, allowing an improvement in the biological performance of tissue-engineered constructs. In this review, we focus on the most relevant strategies to produce electrospun polymer/composite scaffolds with 3D architecture. A detailed description of procedures involving physical and chemical agents to create structures with large pores and 3D fiber assemblies is introduced. Finally, characterization and biological assays including in vitro and in vivo studies of structures intended for the regeneration of functional tissues are briefly presented and discussed.

In this work we show how the optical properties of ZnSe nanowires are modified by the presence of Ag nanoparticles on the sidewalls of the ZnSe nanowires. In particular, we show that the low-temperature luminescence of the ZnSe nanowires changes its shape, enhancing the phonon replicas of impurity-related recombination and affecting rise and decay times of the transient absorption bleaching at room temperatures, with an increase of the former and a decrease of the latter. In contrast, the deposition of Au nanoparticles on ZnSe nanowires does not change the optical properties of the sample. We suggest that the mechanism underlying these experimental observations is energy transfer via a resonant interaction, based on the fact that the localized surface plasmon resonance (LSPR) of Ag nanoparticles spectrally overlaps with absorption and emission of ZnSe, while the Au LSPR does not.

Interfacial heterostructuring has appeared to be an efficient strategy to address the efficiency and applicability of the photocatalysts in solar energy conversion. Herein, we developed one-dimensional (1D) α-Fe₂O₃/TiO₂ nanoheterojunction arrays for enhanced photoelectrochemical (PEC) activity. α-Fe₂O₃ nanotubes were firstly prepared via anodization under controlled hydrodynamic conditions to increase the efficiency. 1D α-Fe₂O₃/TiO₂ nanoheterojunction arrays were then prepared through a hydrothermal treatment and a subsequent annealing process. A controlled anodization by modulating the hydrodynamic conditions, added a fine coating of TiO₂ overlayer, to finally give an optimized composition and geometry for improved light absorption and spatial charge separation efficiency. Consequently, the optimized α-Fe₂O₃ generated a photocurrent of 0.07 mA cm⁻² (3.5 times higher than that of pristine α-Fe₂O₃), and the as-obtained α-Fe₂O₃/TiO₂ nanoheterojunction exhibited a photocurrent intensity of 0.12 mA cm⁻² (about 6 times higher than that of pristine α-Fe₂O₃). A long-term stability can also be ensured. The well-controlled architectures provides a guideline for synthesis of advanced nanomaterials.

Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorganisms on soluble substrates, which often leads to a decrease or loss of the ability to effectively exchange electrons with solid electrode surfaces. In order to develop future sustainable technologies, we cannot rely solely on existing lab-isolates. Therefore, we must develop isolation strategies for environmental strains with electroactive properties superior to strains in culture collections. In this article, we provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor (electricity-generating microorganisms) or a cathode as the sole electron donor (electricity-consuming microorganisms). Next, we recommend a selective strategy for the isolation of electroactive microorganisms. Furthermore, we provide a practical guide for setting up electrochemical reactors and highlight crucial electrochemical techniques to determine electroactivity and the mode of electron transfer in novel organisms.

Mycobacterium tuberculosis is the cause of one of the diseases with the highest mortality and morbidity rate in the Americas and in the world. In developing countries, the diagnosis of tuberculosis (TB) is based on baciloscopy and bacteriological cultures. The first method has a low sensitivity, and the second can take several weeks to reach a confirmatory diagnosis. The lack of a rapid diagnosis compromises the efforts to control this disease and favors the transmission of tuberculosis to the susceptible population. In this work, we present the synthesis, amine-silanization, characterization and bio-functionalization of magnetic nanoparticles (MNPs) to develop a sandwich ELISA to detect and concentrate antigens from M. tuberculosis. For this purpose, a recombinant mycobacterial heat shock protein Hsp16.3, which contributes to the persistence of TB, was cloned and expressed in the E. coli system. Polyclonal antibodies anti-Hsp16.3 were produced in a rabbit and in mice. Magnetic nanoparticles were synthesized by co-precipitation, amine-functionalized and characterized by several physical-chemical methods. The XRD, Mossbauer spectroscopy, zeta potential, TEM, and FTIR all proved the successful preparation of the MNPs showing a diffraction crystal diameter of 10.48 ± 2.56 nm, superficial net charge of $\unicode{x01D8E}$: +23.57 ± 2.87 mV, characteristic patterns of magnetite and a structure similar to a sphere. Additionally, it showed a magnetization saturation of 37.06 emu.g⁻¹. For the functionalization of nanoparticle surfaces with anti-Hsp16.3, the active ester method was used for bond formation, and parameters such as time of incubation, coupling agents ratio (EDC/NHS) and concentration as well as surface saturation level of amine-silanized MNPs (MNP@Si@NH₂) were standardized. Finally, bio-functionalized MNPs were used to detect, fix and concentrate the recombinant antigen Hsp16.3 from M. tuberculosis in a sandwich ELISA-MNP assay.

Carbon quantum dots (CDs) have attracted increased attention in recent decades because of their various applications in biosensing, bioimaging and drug delivery. In the present study, we have synthesized bifunctional ibuprofen-based carbon quantum dots (ICDs) using a simple one-step microwave-assisted method, for simultaneous bioimaging and anti-inflammatory effects. The ICDs exhibited high stability, low toxicity, negligible cytotoxicity and good biocompatibility in water. In particular, the produced ICDs demonstrated a decent imaging ability and excellent anti-inflammatory effects in vivo, making them potentially useful in bioimaging and future clinical treatment. Our results demonstrated that ICDs show promise in applications such as multifunctional biomaterials, depending on the selection of carbon sources, which would provide important guidance for the future design of multifunctional CDs in the field of biomedicine.

Self-assembled polymersomes encapsulate, protect, and deliver hydrophobic and hydrophilic drugs. Though spherical polymersomes are effective, early studies suggest that non-spherical structures may enhance specificity of delivery and uptake due to similarity to endogenous uptake targets. Here we describe a method to obtain persistent non-spherical shapes, prolates, via osmotic pressure and the effect of prolates on uptake behavior. Polyethylene glycol-b-poly(lactic acid) polymersomes change in diameter from 145 ± 6 nm to 191 ± 1 nm and increase in polydispersity from 0.05 ± 0.02 to 0.12 ± 0.01 nm after addition of 50 mM salt. Transmission and scanning electron microscopy confirm changes from spheres to prolates. Prolate-like polymersomes maintain their shape in 50 mM NaCl for seven days. Nile Red and bovine serum albumin-Fluorescein dyes are taken up in greater amounts by SH-SY5Y neural cells when encapsulated in polymersomes. Prolate polymersomes may be taken up more efficiently in neural cells than spherical polymersomes.

Highly efficient broadband absorbing surfaces covering the UV, visible and near-IR regions are of great importance for low-light imaging devices, optical devices and optoelectronic devices. In this work, we demonstrate the fabrication of remarkably efficient absorbing surfaces due to the formation of nanoflower-like cavity structures on a stainless steel (SS304) surface, along with micropatterning in a hierarchical fashion. The fabrication process is carried out using noncontact, programmable, single-step laser irradiation by an inexpensive and robust 532 nm nanosecond laser. The measured specular antireflection properties over a wide spectral region (250–1800 nm) are extremely low, less than 0.5%, over a large range of incident angles and for both orthogonal polarizations. These special hierarchical structures with nanorods, nanoparticles, and nanocavities, completely trap the photon incident on these surfaces due to multiple reflections. These surface structures evolve with time to give better nanostructured features with higher oxygen content on the surfaces, revealed by FESEM elemental analysis, which increases the ability to trap photons. We believe these antireflection surfaces, with high efficiencies and long-term stability, will play a vital role in many modern technological applications.

The increasing demand in energy consumption and the use of clean energy from sustainable energy sources have driven the research in the development of advanced materials for Li-ion and Na-ion batteries. In this work, we have developed a simple technique to synthesize a porous Sb structure through a galvanic replacement reaction between Sb³⁺ and Zn particles. The porous Sb structure consists of a three-dimensional-hierarchical structure with tree-like nanoscale Sb dendrites. The Sb in the nanodendrites is crystal of a rhombohedral structure. We construct Li-/Na-ion half cells and Li-/Na-ion full cells with the Sb nanodendrites as the active material in the working electrode and anode, respectively, and introduce an additive of vinylene carbonate for the Li-ion half/full cells and an additive of fluoroethylene carbonate for the Na-ion half/full cells. All the Li-/Na-ion half cells and Li-/Na-ion full cells exhibit excellent electrochemical performance and cycling stability. Such excellent performance can be attributed to the synergistic interaction between the three-dimensional-dendritic structure and electrolyte, which likely ensures fast transport of ions and electrons and the formation of a stable solid-state interphase.

A gold nanoparticle-based localized surface plasmon resonance substrate has been developed as nano-sensors for various bio-applications. However, reproducible and robust sensing substrates anchored gold nanoparticles has not yet been explored. In this study, dopamine-coated gold nanorods (DGNRs) were prepared and immobilized onto the micro-grooving PDMS substrates (mgPDMS). Subsequently, HER2-specific aptamers were conjugated with DGNR/mgPDMS for ECD-HER2 detection. By screening of the optimal concentration of DGNR and aptamers, the effective HER2-specific aptasensor was built up. In particular, the real-time binding assay for the evaluation of limit-of-detection (<5 ng ml⁻¹) was conducted. Furthermore, the binding kinetics for ECD-HER2 was investigated under the biological fluid using a rat serum. Our HER2-specific aptasensor demonstrated the effective sensitivity and selectivity for ECD-HER2.

Cu–Ag core–shell nanoparticles with a size of 8 nm were synthesized by the compound method of replacement reaction and chemical reduction reaction. A fully covered Cu–Ag core–shell structure was obtained by controlling the two different silver sources and electroless silver plating time. The optimum condition uses silver ammonia reacted for 14 h. The process of electroless silver plating uses the mixed growth model of layered growth and island growth. Silver atoms firstly attach to the surface of the as-prepared copper nanoparticles to form the dotted Ag atom structure by galvanic displacement reaction between Cu and [Ag(NH3)2]+, and then more silver atoms, reduced by sodium citrate, gradually deposit on the copper surface to form a fully covered structure. The morphology and core–shell structure of the nanoparticles was observed by scanning electron microscopy, transmission electron microscopy and x-ray diffraction. The simultaneous thermal analyzer results confirmed that the weight gain of Cu–Ag core–shell nanoparticles was 2.2% when heated up to 400 °C, which was lower than pure Cu nanoparticles. According to the x-ray photoelectron spectroscopy results, the Cu–Ag core–shell nanoparticles exhibited good anti-oxidation performance compared with the pure copper nanoparticles after being stored for one month under the ambient conditions.

Fe₃O₄ nanoparticles coated with chito-oligosaccharides (COS) were prepared in situ by a simple co-precipitation method through a mixing of iron ions (Fe³⁺ and Fe²⁺) and COS aqueous solutions followed by precipitation with ammonia. The impact of COS with different degree of polymerization (DP 10, 24 and 45) and degree of N-acetylation (DA) ∼ 24% and 50% (exhibiting high solubility) on the synthesis and physical properties of the coated magnetic nanoparticles was evaluated. Several advantages were found when the magnetic nanoparticles were prepared in the presence of the studied COS, such as: preparation of functionalized magnetic nanoparticles with narrower size distributions and, consequently, higher saturation magnetization (an increase of up to 22%); and an expressive increasing in the concentration of COS-coated magnetic nanoparticles (up to twice) in the cell viability test in comparison with pure Fe₃O₄ nanoparticles. Furthermore, among the analyzed samples, the magnetic nanoparticles coated by COS with DA ∼ 50% present a higher cytocompatibility. Our results allow envisioning various biomedical applications, valorizing the use of coated-magnetic nanoparticles for magnetic-field assisted drug delivery, enzyme or cell immobilization, or as a marker for specific cell tracking, among others.

In this research work, nanowires were grown on brass (Cu - 37.2 wt% Zn) substrate by thermal oxidation. The substrate was oxidized at temperatures ranging from 350 °C to 600 °C in the presence of varying concentrations of O₂ (1%–100%) in N₂ flown at a rate of 200 sccm. The oxidized brass surface was characterized by field emission scanning electron microscope equipped with energy dispersive x-ray spectroscope and transmission electron microscope. Four different types of morphological variations such as thin, thick with branches, circular-flake and flat-cone shape nanostructures were observed during oxidation at different conditions. However, the prevalence of thin and thick morphology with branches was more prominent and found in all growth conditions. The length and diameter of the nanowires varied from 1 to 30 μm and 50 to 500 nm, respectively, whereas the length of the branches varied from 1 to 3 μm. The composition of the nanowires was ZnO possessing of hexagonal wurtzite structure. The selected area diffraction confirms that the nanowires grew along 〈1 1 $\bar{2}$ 0〉 directions. Based on the results, a stress induced mechanism is proposed for the growth of ZnO nanowires on Cu - 37.2 wt% Zn substrate.

This manuscript presents a simple, one-step method for the fabrication of micro/nanostructured metal-based superhydrophobic surfaces via electroplating using stacked polycarbonate membranes with nanoscale and microscale pores as a template. The two-tiered mushroom-shaped silver pillar arrays include a top layer composed of nanopillars and a bottom layer composed of T-shaped micropillars. The presence of the re-entrant surface structures with a strong resistance pin the droplets to the cap's ridge and prevent water droplets from penetrating into the valleys of the rough surface, thus resulting in an increase in water contact angle (WCA). Compared with microstructured mushroom-shaped surfaces (WCA = 148°, sliding angle (SA) ∼ 26°) and nanostructured surfaces (WCA = 151.5°, SA ∼ 4.8°), the micro/nanostructured mushroom-shaped pillar arrays (WCA = 154.1°, SA ∼ 2°) exhibit remarkable superhydrophobic properties with high CA and low SA. This new micro/nanostructured surface will have a potential application in metal-based superhydrophobic materials.

As one of the transition metal dichalcogenides (TMDs), ReS₂ displays several outstanding properties, while the intrinsically nonmagnetic property limits its applications in spin-related devices. In this study, we selected Cr as the dopant to realize the robust room-temperature ferromagnetism in Cr-doped ReS₂ (Cr-ReS₂) nanosheets. The saturation magnetization (M_s) of the samples can be tuned by changing the Cr concentration. Density functional theory calculation results reveal that Cr dopant can provide the magnetic moments and stable ferromagnetic coupling in Cr-doped ReS₂ system. This finding provides an effective approach for designing the new magnetic TMDs in spintronics devices.

Highly dispersed cobalt atoms were deposited on porous alumina particles using atomic layer deposition (ALD) with a CoCp₂/H₂ chemistry at approximately 7 wt%. H₂ did not completely reduce the cyclopentadienyl organic ligands bound to deposited Co atoms at ALD reaction conditions. A sharp decline in Co deposited per cycle for two or more ALD cycles indicates that much of the Al₂O₃ surface is sterically blocked from further CoCp₂ deposition after the first CoCp₂ exposure. Temperature programmed reduction confirmed that the adsorbed precursor organic ligands persist after H₂ exposures during ALD and temperatures as high as 500 °C are required to fully reduce the organic ligands to CH₄. High resolution, element sensitive imaging showed that Co atoms were dispersed on the Al₂O₃ surface and could deposit in previously unobserved multiple growth morphologies, specifically layers that were continuous over several angstroms or discrete nanoparticles. Density functional theory calculations were used to examine Co atom adsorption, show the altered haptic binding of cracked Cp ligands, and to calculate the thermodynamics of Cp ligand decomposition. The lateral steric hindrance between organic ligands bound to deposited Co atoms, Cp ligand decomposition mechanism, and local Al₂O₃ surface termination all likely determine the observed Co growth morphology during initial ALD cycles.

In this paper, we perform molecular dynamics simulations to propose a novel bio-inspired nanopumping mechanism that is achieved through the rotation of graphene nanoribbons. Due to the rotation and interaction with water, the graphene nanoribbons undergo morphological transformation. It is shown that with appropriate geometrical and spatial parameters, the resulting morphology is twisted ribbon, which is efficient in pumping of water through a channel. This mimics the propulsive behavior of bacterial flagella through continual rotation at the base and causing morphology of the geometry into twisted ribbons, thus driving flow. It was observed that the maximum flux rate decreases upon reaching the optimal configuration even with increasing rotational speed and graphene width. This is due to the development of cavitation near the region of the nanoribbon with tip velocities approaching the speed of sound in water. The simulation shows promising results where the flux rate of the driven flow outperforms various nanopump configurations that have been reported in recent literature by more than one order.

Due to the resistance to drugs, studies involving the combination and controlled release of different agents are gradually increasing. In this study, two different active ingredients, known to have antibacterial and antiparasitic activities, were encapsulated into single polymeric nanoparticles. After co-encapsulation their antibacterial and antileishmanial activity was enhanced approximately 5 and 250 times, respectively. Antibacterial and antileishmanial activities of caffeic acid phenethyl ester and juglone loaded, multifunctional nanoformulations (CJ4-CJ6-CJ8) were also evaluated for the first time in the literature comparatively with their combined free formulations. The antibacterial activity of the multifunctional nanoformulation (CJ8) were found to have a much higher activity (MIC values 6.25 and 12.5 μg ml⁻¹ for S. aureus and E. coli, respectively) than all other formulations. Similar efficacy for CJ8 was obtained in the antiparasitic study against the Leishmania promastigotes and the IC₅₀ was reduced to 0.1263 μg ml⁻¹. The high activity of multifunctional nanoparticles is not only due to the synergistic effect of the active molecules but also by the encapsulation into polymeric nanoparticles. Therefore, it has been shown in the literature for the first time that the biological activity of molecules whose activity is increased by the synergistic effect can be improved with nanosystems.