Tunable Nanoparticles Research Articles

PEI-Engineered Lipid@PLGA Hybrid Nanoparticles for Multimodal Delivery of Antigens and Immune Adjuvants to the Respiratory Mucosa.

Antigen delivery via respiratory mucosal surfaces is an interesting needle-free option for vaccination. Nonetheless, it demands for the design of especially tailored formulations. Here, lipid/poly(lactic-co-glycolic) acid (PLGA) hybrid nanoparticles (hNPs) for the combined delivery of an antigen, ovalbumin (Ova), and an adjuvant, synthetic unmethylated cytosine-phosphate-guanine oligodeoxynucleotide (CpG) motifs, is developed. A panel of Ova/CpG-loaded lipid@PLGA hNPs with tunable size and surface is attained by exploiting two lipid moieties, 1,2 distearoil-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG) and monophosphoryl lipid A (MPLA), with or without polyethyleneimine (PEI). It is gained insights on the lipid@PLGA hNPs through a combination of techniques to analytically determine the specific moiety on the surface, the spatial distribution of the components and the internal structure of the nanoplatforms. The collected results suggest that PEI plays a role of paramount importance not only in promoting in vitro antigen escape from lysosomes and enhancing antigen cross-presentation, but also in determining the arrangement of the moieties in the final architecture of the hNPs. Though multicomponent PEI-engineered lipid@PLGA hNPs turn out as a viable strategy for delivery of antigens and adjuvant to the respiratory mucosa, tunable nanoparticle features are achievable only through the optimal selection of the components and their relative amounts.

Aloe vera-assisted biogenic synthesis of tunable magnesium oxide nanoparticles for enhanced photocatalytic and antibacterial applications

In this study, magnesium oxide (MgO) nanoparticles (NPs) tuned via doping with transition metal ions, Co2+/Cu2+/Zn2+ have been synthesized biologically using Aloe vera leaf extract as an encapsulating agent. These pure and doped MgO NPs have been characterized by using various physico-chemical characterization techniques. X-ray diffraction (XRD) analysis confirms the formation of face-centered cubic structures of pure and doped MgO NPs with their average crystallite sizes ranging from 8.11-17.83 nm. X-ray photoelectron spectroscopic (XPS) analysis confirmed the presence of doped element in their +2 oxidation state. UV-Visible spectral analysis revealed a significant reduction in band gap energies in nano-dimensions which further gets modified upon doping (1.76 − 4.9 eV). Our findings also demonstrated the engagement of phytochemicals as capping agents in Fourier transform infrared (FTIR) examination. Scanning electron microscopic (SEM) and Transmission electron microscopic (TEM) analysis provided insights into the morphologies and particle sizes. Elemental analysis by Energy dispersive X-ray (EDX) confirms the presence of Co, Cu, and Zn elements in doped MgO NPs. The photocatalytic degradation of dyes has confirmed that Co and Cu doping substantially enhance the photocatalytic activity compared to both undoped and Zn-doped MgO NPs. Furthermore, these nanoparticles demonstrate superior efficiency in degrading the cationic dye Malachite green (MG) compared to the anionic dye Methyl orange (MO). Regarding their antibacterial properties, only Cu doping induces a notable antibacterial effect in MgO NPs, particularly against gram-positive bacteria. Additionally, these nanoparticles exhibit substantial antioxidant activities. These tailored MgO nanoparticles exhibit potential for applications in wastewater treatment.

A Lung-Expressing mRNA Delivery Platform with Tunable Activity in Hypoxic Environments.

Messenger RNA (mRNA) delivery platforms often facilitate protein expression in the liver following intravenous injection and have been optimized for use in normally oxygenated cells (21% O2 atmosphere). However, there is a growing need for mRNA therapy in diseases affecting non-liver organs, such as the lungs. Additionally, many diseases are characterized by hypoxia (<21% O2 atmosphere), a state of abnormally low oxygenation in cells and tissues that can reduce the efficacy of mRNA therapies by upwards of 80%. Here, we report a Tunable Lung-Expressing Nanoparticle Platform (TULEP) for mRNA delivery, whose properties can be readily tuned for optimal expression in hypoxic environments. Briefly, our study begins with the synthesis and characterization of a novel amino acrylate polymer that can be effectively complexed with mRNA payloads into TULEPs. We study the efficacy and mechanism of mRNA delivery using TULEP, including analysis of the cellular association, endocytosis mechanisms, endosomal escape, and protein expression in a lung cell line. We then evaluate TULEP under hypoxic conditions and address hypoxia-related deficits in efficacy by making our system tunable with adenosine triphosphate (ATP). Finally, we conclude our study with an in vivo analysis of mRNA expression, biodistribution, and tolerability of the TULEP platform in mice. In presenting these data, we hope that our work highlights the utility of TULEPs for tunable and effective mRNA delivery while more broadly highlighting the utility of considering oxygen levels when developing mRNA delivery platforms.

Promotion of Th17 Polarized Immunity via Co-Delivery of Mincle Agonist and Tuberculosis Antigen Using Silica Nanoparticles.

Adjuvants and immunomodulators that effectively drive a Th17-skewed immune response are not part of the standard vaccine toolkit. Vaccine adjuvants and delivery technologies that can induce Th17 or Th1/17 immunity and protection against bacterial pathogens, such as tuberculosis (TB), are urgently needed. Th17-polarized immune response can be induced using agonists that bind and activate C-type lectin receptors (CLRs) such as macrophage inducible C-type lectin (Mincle). A simple but effective strategy was developed for codelivering Mincle agonists with the recombinant Mycobacterium tuberculosis fusion antigen, M72, using tunable silica nanoparticles (SNP). Anionic bare SNP, hydrophobic phenyl-functionalized SNP (P-SNP), and cationic amine-functionalized SNP (A-SNP) of different sizes were coated with three synthetic Mincle agonists, UM-1024, UM-1052, and UM-1098, and evaluated for adjuvant activity in vitro and in vivo. The antigen and adjuvant were coadsorbed onto SNP via electrostatic and hydrophobic interactions, facilitating multivalent display and delivery to antigen presenting cells. The cationic A-SNP showed the highest coloading efficiency for the antigen and adjuvant. In addition, the UM-1098-adsorbed A-SNP formulation demonstrated slow-release kinetics in vitro, excellent stability over 12 months of storage, and strong IL-6 induction from human peripheral blood mononuclear cells. Co-adsorption of UM-1098 and M72 on A-SNP significantly improved antigen-specific humoral and Th17-polarized immune responses in vivo in BALB/c mice relative to the controls. Taken together, A-SNP is a promising platform for codelivery and proper presentation of adjuvants and antigens and provides the basis for their further development as a vaccine delivery platform for immunization against TB or other diseases for which Th17 immunity contributes to protection.

Effect of Micromixer Design on Lipid Nanocarriers Manufacturing for the Delivery of Proteins and Nucleic Acids.

Lipid-based nanocarriers have emerged as helpful tools to deliver sensible biomolecules such as proteins and oligonucleotides. To have a fast and robust microfluidic-based nanoparticle synthesis method, the setup of versatile equipment should allow for the rapid transfer to scale cost-effectively while ensuring tunable, precise and reproducible nanoparticle attributes. The present work aims to assess the effect of different micromixer geometries on the manufacturing of lipid nanocarriers taking into account the influence on the mixing efficiency by changing the fluid-fluid interface and indeed the mass transfer. Since the geometry of the adopted micromixer varies from those already published, a Design of Experiment (DoE) was necessary to identify the operating (total flow, flow rate ratio) and formulation (lipid concentration, lipid molar ratios) parameters affecting the nanocarrier quality. The suitable application of the platform was investigated by producing neutral, stealth and cationic liposomes, using DaunoXome®, Myocet®, Onivyde® and Onpattro® as the benchmark. The effect of condensing lipid (DOTAP, 3-10-20 mol%), coating lipids (DSPE-PEG550 and DSPE-PEG2000), as well as structural lipids (DSPC, eggPC) was pointed out. A very satisfactory encapsulation efficiency, always higher than 70%, was successfully obtained for model biomolecules (myoglobin, short and long nucleic acids).

Leveraging Tunable Nanoparticle Surface Functionalization to Alter Cellular Migration.

Gold nanoparticles (AuNPs) are a promising platform for biomedical applications including therapeutics, imaging, and drug delivery. While much of the literature surrounding the introduction of AuNPs into cellular systems focuses on uptake and cytotoxicity, less is understood about how AuNPs can indirectly affect cells via interactions with the extracellular environment. Previous work has shown that the monocytic cell line THP-1's ability to undergo chemotaxis in response to a gradient of monocyte chemoattractant protein 1 (MCP-1) was compromised by extracellular polysulfonated AuNPs, presumably by binding to MCP-1 with some preference over other proteins in the media. The hypothesis to be explored in this work is that the degree of sulfonation of the surface would therefore be correlated with the ability of AuNPs to interrupt chemotaxis. Highly sulfonated poly(styrenesulfonate)-coated AuNPs caused strong inhibition of THP-1 chemotaxis; by reducing the degree of sulfonation on the AuNP surface with copolymers [poly(styrenesulfonate-co-maleate) of different compositions], it was found that medium and low sulfonation levels caused weak to no inhibition, respectively. Small, rigid molecular sulfonate surfaces were relatively ineffective at chemotaxis inhibition. Unusually, free poly(styrenesulfonate) caused a dose-dependent reversal of THP-1 cell migration: at low concentrations, free poly(styrenesulfonate) significantly inhibited MCP-1-induced chemotaxis. However, at high concentrations, free poly(styrenesulfonate) acted as a chemorepellent, causing a reversal in the cell migration direction.

Elemental analysis of liquid samples by nanoparticle-enhanced laser-induced breakdown spectroscopy: using ordered nano-arrays with a tunable nanoparticle size and inter-particle distance

NELIBS analysis of liquid samples using ordered nanoparticle arrays with a precisely tunable nanoparticle size and inter-particle distance, which provide excellent homogeneity to ensure signal reproducibility and enhancement.

Strong, UV-blocking, and hydrophobic PVA composite films containing tunable lignin nanoparticles

In the present work, hollow and solid lignin nanoparticles (LNPs) were synthesized through a self-assembling process using the organosolv pretreatment of lignin from the eucalyptus and willow byproducts. The SEM, TEM, and zeta potential establish the LNPs of a uniform spherical morphology, and the hollow lignin nanoparticles (HLNPs) display the inner cavity and shell. The polyvinyl alcohol (PVA) nanocomposite films containing the LNPs suggest that the presence of HLNPs results in a “room” like network structure in the films and differs from the solid lignin nanoparticles (SLNPs) induced structural changes. The LNPs inclusion increases the mechanical properties. The films with solid eucalyptus lignin nanoparticles showed excellent tensile strength (132 MPa), while those with hollow eucalyptus lignin nanoparticles resulted in exceptional elongation at break (324%). Hydrophobicity tests revealed that both LNPs incorporation in the PVA film results in a water contact angle of more than 90°. The outcome promises novel opportunities for LNPs in the designing and development of plastic replacement packaging films.

Tunable polymeric micelles for taxane and corticosteroid co-delivery

Nanomedicine holds promise for potentiating drug combination therapies. Increasing (pre)clinical evidence is available exemplifying the value of co-formulating and co-delivering different drugs in modular nanocarriers. Taxanes like paclitaxel (PTX) are widely used anticancer agents, and commonly combined with corticosteroids like dexamethasone (DEX), which besides for suppressing inflammation and infusion reactions, are increasingly explored for modulating the tumor microenvironment towards enhanced nano-chemotherapy delivery and efficacy. We here set out to develop a size- and release rate-tunable polymeric micelle platform for co-delivery of taxanes and corticosteroids. We synthesized amphiphilic mPEG-b-p(HPMAm-Bz) block copolymers of various molecular weights and used them to prepare PTX and DEX single- and double-loaded micelles of different sizes. Both drugs could be efficiently co-encapsulated, and systematic comparison between single- and co-loaded formulations demonstrated comparable physicochemical properties, encapsulation efficiencies, and release profiles. Larger micelles showed slower drug release, and DEX release was always faster than PTX. The versatility of the platform was exemplified by co-encapsulating two additional taxane-corticosteroid combinations, demonstrating that drug hydrophobicity and molecular weight are key properties that strongly contribute to drug retention in micelles. Altogether, our work shows that mPEG-b-p(HPMAm-Bz) polymeric micelles serve as a tunable and versatile nanoparticle platform for controlled co-delivery of taxanes and corticosteroids, thereby paving the way for using these micelles as a modular carrier for multidrug nanomedicine.Graphical abstract

Green production of tunable multicolor nanoparticles with diamond structure from long-flame coal by a one-step mild oxidation

The complex compositions and structural features of low-rank coal obstruct its wide use in materials applications directly. Graphene nanocarbon hydrosol with uniform particle size and containing nanodiamond structures were prepared from long-flame coal by a simple H2O2 oxidation, achieving the highest extraction rate of 30.86%, and the depolymerization degree was 80.21% when the temperature was 80 °C. The average diameter of the carbon nanoparticles was 1.86 ± 0.62 nm with 2–3 graphite flake layers, and these graphite flake layers were derived from the stable crystalline domains in the raw coal. Carbon nanoparticles exhibited good excitation wavelength-dependent and concentration-dependent fluorescence, which can be tunable from blue to green fluorescence by adjusting the concentration (0.19–1.5 g/L) and excitation wavelength (340–460 nm), the reason may be due to the combined effect of the relative intensity changes of various types of oxygenous groups, low-lying effects resulting from n(OH)→π*(CO) interactions between the hydroxyl groups and carbonyl groups, and the aggregation of particle. The post-reaction residue has a similar structural composition to that of humic acid and could be used for developing functional materials and agricultural restoration. Therefore, preparing carbon nanoparticles and humic acid by mild oxidation of hydrogen peroxide for the high-value utilization of long-flame coal has good application prospects.

Au-CeO2 composite aerogels with tunable Au nanoparticle sizes as plasmonic photocatalysts for CO2 reduction

Tuning the size of Au nanoparticles is always an interesting task when constructing Au/semiconductor heterojunctions for surface plasmon resonance-enhanced photocatalysis. In particular, the size of Au nanoparticles in the newly emerging “plasmonic aerogel” photocatalyst concept could approach the size of the semiconductor phase. This work provides an alternative route to realize the size tuning of Au nanoparticles in Au-CeO2 composite aerogels to some extent, within the framework of the well-established epoxide addition sol–gel method. The size tuning is achieved by exploiting the multi-functionalities of a mixed organic acid additive containing a thiol group in the gelation step. The obtained aerogel photocatalysts are composed of a porous backbone of interconnected CeO2 nanoparticles and Au nanoparticles, and the size of Au nanoparticles ranges from ∼30 nm to sub-10 nm, while the size of CeO2 remains at ∼15–10 nm. The surface plasmon resonance peak position and intensity contributed by the Au nanoparticles then vary accordingly. Photocatalytic CO2 reduction at the gas–solid interface is chosen as a model reaction to study the effect of Au nanoparticle size on the photocatalytic activity of composite aerogel photocatalysts. The addition of Au nanoparticles undoubtedly enhances the overall activity of the CeO2 aerogel photocatalyst, while the degree of enhancement (in terms of total charge consumption) and product selectivity (CH4 or CO) are different and correlated with the size of the Au nanoparticles. The best performance can be achieved in a composite in which the Au sizes are the smallest.

Fe-FeNn nanoparticles anchored bamboo-like morphology of N-doped graphitic carbon nitride nanotubes enabled electrochemical DNA-based biosensing of head and neck-squamous cell carcinoma miRNA-203

We describe a biosensing platform for the early screening of metastatic lymph nodes in patients with head and neck squamous-cell-carcinoma. The tunable iron nanoparticles (Fe-FeNn) inserted bamboo-like nanostructured N-doped carbon nanotubes (CNTs) obtained from a graphitic carbon nitride (GCN) are a source material for the highly sensitive detection of miRNA-203 in human serum and urine samples. The CNTs/GCN with tunable Fe precursors annealed at 900 °C enables the formation of Fe-FeNn nanoparticles (n = 0.5, 1.0, and 2.0 mmol of Fe) intercalated bamboo-like morphology of CNTs/GCN, which is denoted as Fe-FeNn/CNTs/GCN nanocomposite. Particularly, the bamboo-like nanotubes were derived from layered-structure of graphitic carbons with several voids and pores. The synthesized bamboo-like Fe-FeNn/CNTs/GCN was used to construct a biosensing platform through coordinate covalent bonding between Fe-FeNn and phosphate functionality of probe DNA. The developed bamboo-like Fe-FeNn/CNTs/GCN-based biosensing platform exhibited potential detection toward cancerous miRNA from 10 to 5000 fM with the limit of detection of 0.11 fM (S/N = 3). Under optimized conditions, the developed Fe-FeNn/CNTs/GCN biosensing platform was applied to detect miRNA in complexed biological fluids, such as human blood serum and saliva samples with satisfied recovery results (94.22%–97.40%).

Interfacial arrangement of tunable gliadin nanoparticles via electrostatic assembly with pectin: Enhancement of foaming property

Gliadin nanoparticles (GNPs) have impressive foaming properties, but their foam capacity and stability are sensitive to acidic pH, due to inferior interfacial properties. To regulate the interfacial behavior, pectin was introduced to surface modulation of GNPs and its influence on the structure, interfacial properties, and macroscopic foaming performances of GNPs at a pH of 3.5–5.8 was discussed. Results exhibited that pectin and gliadin could form complex nanoparticles (GPNPs) at pH ranging from 3.5 to 5.8, mainly through electrostatic interaction. The half-life time of foam covered by GPNPs at pH 3.5 were about 160-fold larger than that of GNPs at the same pH. This was because the large GPNPs with irregular shape exhibited hard particle-like characteristic and could not deform at the interface, but interestingly, they closely arranged at the interface in a seemingly stacked way. This led to the high particle coverage and the formation of the steric barrier layer, which effectively prevented foam from disproportionation and coalescence. Besides, the unadsorbed GPNPs located at the Plateau borders could act as corks to slow down the drainage. With respect to GPNPs at pH 5.8, they displayed the deformable property at the interface and adjacent GPNPs could cross-linked by pectin to form a tight interfacial layer. GPNPs displayed high foamability, strong foam plasticity, and long-term stability simultaneously in a broad pH range, demonstrating that they can be utilized as an efficient foaming agent for fabricating foamed food.

Tunable Nanoparticles with Aggregation-Induced Emission Heater for Precise Synergistic Photothermal and Thermodynamic Oral Cancer Therapy of Patient-Derived Tumor Xenograft.

The fluorophores in the second near-infrared (NIR-II) biological window (1000 - 1700nm) show great application prospects in the fields of biology and optical communications. However, both excellent radiative transition and nonradiative transition cannot be achieved simultaneously for the majority of traditional fluorophores. Herein, tunable nanoparticles formulated with aggregation-induced emission (AIE) heater are developed rationally. The system can be implemented via the development of an ideal synergistic system that can not only produce photothermal from nonspecific triggers but also trigger carbon radical release. Once accumulating in tumors and subsequently being irradiated with 808nm laser, the nanoparticles (NMB@NPs) encapsulated with NMDPA-MT-BBTD (NMB) are splitted due to the photothermal effect of NMB, leading to the decomposition of azo bonds in the nanoparticle matrix to generate carbon radical. Accompanied by second near-infrared (NIR-II) window emission from the NMB, fluorescence image-guided thermodynamic therapy (TDT) and photothermal therapy (PTT) which significantly inhibited the growth of oral cancer and negligible systemic toxicity is achieved synergistically. Taken together, this AIE luminogens-based synergistic photothermal-thermodynamic strategy brings a new insight into the design of superior versatile fluorescent NPs for precise biomedical applications and holds great promise to enhance the therapeutic efficacy of cancer therapy.

High-entropy NaCl-type metal chalcogenides as K-ion storage materials: role of the cocktail effect

The drastic volume expansion of active materials and the shuttle effect of polychalcogenides hindered the development of anode materials for potassium-ion batteries (PIBs). Thus, various strategies have been used to overcome the negative effects associated with potassiation. Here, we propose a NaCl-type high-entropy metal chalcogenide (HEMC) prepared using a simple melting method as an anode material for PIBs. Unlike traditional high-entropy materials comprising inactive metals, NaCl-type HEMCs can realize the occupancy of cationic sites by active metals. We show that AgSnSbSe1.5Te1.5, a HEMC, produces short-range tiny cells during phase-change energy storage reactions, reconciling the participation of active and inactive metals to form various heterointerfaces and different functional metal nanoparticles. The kinetic and density functional theory analysis showed that the formation of heterointerfaces decreased the diffusion energy barrier of K+ and the inactive metal silver provided appropriate adsorption energy, suppressing the latent shuttle effect. The results show enhanced electrochemical performance owing to the elemental composition of high-entropy materials and the formation of tunable heterointerfaces and functional nanoparticles in electrochemical reactions, offering a new concept for the design of PIB anode materials.

Alloying as a Strategy to Boost the Stability of Copper Nanocatalysts during the Electrochemical CO2 Reduction Reaction.

Copper nanocatalysts are among the most promising candidates to drive the electrochemical CO2 reduction reaction (CO2RR). However, the stability of such catalysts during operation is sub-optimal, and improving this aspect of catalyst behavior remains a challenge. Here, we synthesize well-defined and tunable CuGa nanoparticles (NPs) and demonstrate that alloying Cu with Ga considerably improves the stability of the nanocatalysts. In particular, we discover that CuGa NPs containing 17 at. % Ga preserve most of their CO2RR activity for at least 20 h while Cu NPs of the same size reconstruct and lose their CO2RR activity within 2 h. Various characterization techniques, including X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy, suggest that the addition of Ga suppresses Cu oxidation at open-circuit potential (ocp) and induces significant electronic interactions between Ga and Cu. Thus, we explain the observed stabilization of the Cu by Ga as a result of the higher oxophilicity and lower electronegativity of Ga, which reduce the propensity of Cu to oxidize at ocp and enhance the bond strength in the alloyed nanocatalysts. In addition to addressing one of the major challenges in CO2RR, this study proposes a strategy to generate NPs that are stable under a reducing reaction environment.

Valorization of Lignin Based Nanoparticle from Grass Biomass: An Overview on Synthesis, Characterization and Application

The Lignin-related nanomaterials have received a lot of attention from the academic and industry communities in the present nanotechnology research area. Advanced performance can be provided by converting lignin into micro and nanostructures, which may be formed using practical standard apparatus. To improve the functionality of the applications, tunable lignin nanoparticles may also be produced. Because lignin contains a variety of chemical moieties and has a unique network structure, it has useful qualities such UV absorbance, biodegradability, stabilizing and reinforcing effects, as well as anti-fungal and antibiotic action. Thus, the nanoscale transformation of lignin and its translation into nanomaterials might definitely open up new possibilities for the development of novel materials with intriguing features.

Scalability of U-Shape Magnetic Nanoparticles-Based Microreactor–Lipase-Catalyzed Preparative Scale Kinetic Resolutions of Drug-like Fragments

The production of active pharmaceutical ingredients (APIs) and fine chemicals is accelerating due to the advent of novel microreactors and new materials for immobilizing customized biocatalysts that permit long-term use in continuous-flow reactors. This work studied the scalability of a tunable U-shape magnetic nanoparticles (MNPs)-based microreactor. The reactor consisted of a polytetrafluoroethylene tube (PTFE) of various inner diameters (ID = 0.75 mm, 1.50 mm, or 2.15 mm) and six movable permanent magnets positioned under the tube to create reaction chambers allowing the fluid reaction mixture to flow through and above the enzyme-loaded MNPs anchored by permanent magnets. The microreactors with various tube sizes and MNP capacities were tested with the preparative scale kinetic resolution of the drug-like alcohols 4-(3,4-dihydroisoquinolin-2(1H)-yl)butan-2-ol (±)-1a and 4-(3,4-dihydroquinolin-1(2H)-yl)butan-2-ol (±)-1b, utilizing Lipase B from Candida antarctica immobilized covalently onto MNPs, leading to highly enantioenriched products [(R)-2a,b and (S)-1a,b]. The results in the U-shape MNP flow reactor were compared with reactions in the batch mode with CaLB-MNPs using similar conditions. Of the three different systems, the one with ID = 1.50 mm showed the best balance between the maximum loading capacity of biocatalysts in the reactor and the most effective cross-section area. The results showed that this U-shaped tubular microreactor might be a simple and flexible instrument for many processes in biocatalysis, providing an easy-to-set-up alternative to existing techniques.

Activity of Retinal Neurons Can Be Modulated by Tunable Near-Infrared Nanoparticle Sensors.

The vision of patients rendered blind by photoreceptor degeneration can be partially restored by exogenous stimulation of surviving retinal ganglion cells (RGCs). Whereas conventional electrical stimulation techniques have failed to produce naturalistic visual percepts, nanoparticle-based optical sensors have recently received increasing attention as a means to artificially stimulate the RGCs. In particular, nanoparticle-enhanced infrared neural modulation (NINM) is a plasmonically mediated photothermal neuromodulation technique that has a demonstrated capacity for both stimulation and inhibition, which is essential for the differential modulation of ON-type and OFF-type RGCs. Gold nanorods provide tunable absorption through the near-infrared wavelength window, which reduces interference with any residual vision. Therefore, NINM may be uniquely well-suited to retinal prosthesis applications but, to our knowledge, has not previously been demonstrated in RGCs. In the present study, NINM laser pulses of 100 μs, 500 μs and 200 ms were applied to RGCs in explanted rat retinae, with single-cell responses recorded via patch-clamping. The shorter laser pulses evoked robust RGC stimulation by capacitive current generation, while the long laser pulses are capable of inhibiting spontaneous action potentials by thermal block. Importantly, an implicit bias toward OFF-type inhibition is observed, which may have important implications for the feasibility of future high-acuity retinal prosthesis design based on nanoparticle sensors.

Selectivity tunable iron nanoparticles from lignocellulosic components for the reductive amination of carbonyl compounds towards switchable products

The regulatory mechanism of reductive amination by selectivity tunable iron nanoparticles, which enables the synthesis of various products from carbonyl compounds with excellent efficiency, was explored.