Facile Fabrication of Multifunctional Hydrogel Nanoweb Coating Using Carboxymethyl Chitosan-Based Short Nanofibers for Blood-Contacting Medical Devices.

Blood-contacting medical devices (BCDs) require antithrombotic, antibacterial, and low-friction surfaces. Incorporating a nanostructured surface with the functional hydrogel onto BCD surfaces can enhance the performances; however, their fabrication remains challenging. Here, we introduce a straightforward method to fabricate a multifunctional hydrogel-based nanostructure on BCD surfaces using O-carboxymethyl chitosan-based short nanofibers (CMC-SNFs). CMC-SNFs, fabricated via electrospinning and cutting processes, are easily sprayed and entangled onto the BCD surface. The deposited CMC-SNFs form a robust nanoweb layer via fusion at the contact area of the nanofiber interfaces. The superhydrophilic CMS-SNF nanoweb surface creates a water-bound layer that effectively prevents the nonspecific adhesion of bacteria and blood cells, thereby enhancing both antimicrobial and antithrombotic performances. Furthermore, the CMC-SNF nanoweb exhibits excellent lubricity and durability on the bovine aorta. The demonstration results of the CMC-SNF coating on catheters and sheaths provide evidence of its capability to apply multifunctional surfaces simply for diverse BCDs.

A radioactive CRISPR interference system using 89Zr-labeled LbCas12a.

Recently, CRISPR proteins have been recognized as promising candidates for drug development. However, there is still a lack of substances with the appropriate sensitivity and stability for targeted drug delivery systems. 89Zr is a radioactive isotope that emits positrons, allowing real-time in vivo tracking with proven safety. In this study, we confirmed that labeling with 89Zr did not compromise the functionality of CRISPR proteins during in vivo behavioral imaging. Furthermore, we demonstrated the therapeutic efficacy of the CRISPR interference system in a mouse model of liver fibrosis, highlighting the theragnostic potential of isotope-labeled CRISPR proteins. The findings of this research could contribute to various aspects of ongoing clinical studies exploring the in vivo applications of CRISPR proteins.

Crack-Based Sensor with Microstructures for Strain and Pressure Sensing.

Recent extensive research on flexible electronics has led to the development of various flexible sensors. In particular, sensors inspired by the slit organs of a spider, which utilize cracks in a metal film to measure strain, have garnered considerable interest. This method exhibited significantly high sensitivity, repeatability, and durability in measuring strain. In this study, a thin-film crack sensor was developed using a microstructure. The results exhibited its ability to simultaneously measure the tensile force and pressure in a thin film, further expanding its applications. Furthermore, the strain and pressure characteristics of the sensor were measured and analyzed using an FEM simulation. The proposed method is expected to contribute to the future development of wearable sensors and artificial electronic skin research.

Discovery of 3,7-dimethoxyflavone that inhibits liver fibrosis based on dual mechanisms of antioxidant and inhibitor of activated hepatic stellate cell.

The important pathway toward liver fibrosis is the TGF-ß1-induced activation of hepatic stellate cells (HSCs). To discover chemicals to inhibit liver fibrosis, we screened 3000 chemicals using cell array system where human HSCs line LX2 cells are activated with TGF-ß1. We discovered 3,7-dimethoxyflavone (3,7-DMF) as a chemical to inhibit TGF-ß1-induced activation of HSCs. In the thioacetamide (TAA)-induced mouse liver fibrosis model, 3,7-DMF treatment via intraperitoneal or oral administration prevented liver fibrosis as well as reversed the established fibrosis in the separate experiments. It also reduced liver enzyme elevation, suggesting protective effect on hepatocytes because it has antioxidant effect. Treatment with 3,7-DMF induced antioxidant genes, quenches ROS away, and improved the hepatocyte condition that was impaired by H2O2 as reflected by restoration of HNF-4α and albumin. In the TAA-mouse liver injury model also, TAA significantly increased ROS in the liver which led to decrease of albumin and nuclear expression of HNF-4α, increase of TGF-ß1 and hepatocytes death, accumulation of lipid, and extra-nuclear localization of HMGB1. Treatment of 3,7-DMF normalized all these pathologic findings and prevented or resolved liver fibrosis. In conclusion, we discovered 3,7-DMF that inhibits liver fibrosis based on dual actions; antioxidant and inhibitor of TGF-ß1-induced activation of HSCs.

Superior Heavy Metal Ion Adsorption Capacity in Aqueous Solution by High-Density Thiol-Functionalized Reduced Graphene Oxides.

The preparation of mercapto-reduced graphene oxides (m-RGOs) via a solvothermal reaction using P4S10 as a thionating agent has demonstrated their potential as an absorbent for scavenging heavy metal ions, particularly Pb2+, from aqueous solutions due to the presence of thiol (-SH) functional groups on their surface. The structural and elemental analysis of m-RGOs was conducted using a range of techniques, including X-ray diffraction (XRD), Raman spectroscopy, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy equipped with energy-dispersive spectroscopy (STEM-EDS), and X-ray photoelectron spectroscopy (XPS). At pH 7 and 25 °C, the maximum adsorption capacity of Pb2+ ions on the surface of m-RGOs was determined to be approximately 858 mg/g. The heavy metal-S binding energies were used to determine the percent removal of the tested heavy metal ions, with Pb2+ exhibiting the highest percentage removal, followed by Hg2+ and Cd2+ ions having the lowest percent removal, and the binding energies observed were Pb-S at 346 kJ/mol, Hg-S at 217 kJ/mol, and Cd-S at 208 kJ/mol. The time-dependent removal study of Pb2+ ions also yielded promising results, with almost 98% of Pb2+ ions being removed within 30 min at pH 7 and 25 °C using a 1 ppm Pb2+ solution as the test solution. The findings of this study clearly demonstrate the potential and efficiency of thiol-functionalized carbonaceous material for the removal of environmentally harmful Pb2+ from groundwater.

Mg2+-dependent conformational rearrangements of CRISPR-Cas12a R-loop complex are mandatory for complete double-stranded DNA cleavage.

CRISPR-Cas12a, an RNA-guided DNA targeting endonuclease, has been widely used for genome editing and nucleic acid detection. As part of the essential processes for both of these applications, the two strands of double-stranded DNA are sequentially cleaved by a single catalytic site of Cas12a, but the mechanistic details that govern the generation of complete breaks in double-stranded DNA remain to be elucidated. Here, using single-molecule fluorescence resonance energy transfer assay, we identified two conformational intermediates that form consecutively following the initial cleavage of the nontarget strand. Specifically, these two intermediates are the result of further unwinding of the target DNA in the protospacer-adjacent motif (PAM)-distal region and the subsequent binding of the target strand to the catalytic site. Notably, the PAM-distal DNA unwound conformation was stabilized by Mg2+ ions, thereby significantly promoting the binding and cleavage of the target strand. These findings enabled us to propose a Mg2+-dependent kinetic model for the mechanism whereby Cas12a achieves cleavage of the target DNA, highlighting the presence of conformational rearrangements for the complete cleavage of the double-stranded DNA target.

KAI1(CD82) is a key molecule to control angiogenesis and switch angiogenic milieu to quiescent state.

BACKGROUND: Little is known about endogenous inhibitors of angiogenic growth factors. In this study, we identified a novel endogenous anti-angiogenic factor expressed in pericytes and clarified its underlying mechanism and clinical significance. METHODS: Herein, we found Kai1 knockout mice showed significantly enhanced angiogenesis. Then, we investigated the anti-angiogenic roll of Kai1 in vitro and in vivo. RESULTS: KAI1 was mainly expressed in pericytes rather than in endothelial cells. It localized at the membrane surface after palmitoylation by zDHHC4 enzyme and induced LIF through the Src/p53 pathway. LIF released from pericytes in turn suppressed angiogenic factors in endothelial cells as well as in pericytes themselves, leading to inhibition of angiogenesis. Interestingly, KAI1 had another mechanism to inhibit angiogenesis: It directly bound to VEGF and PDGF and inhibited activation of their receptors. In the two different in vivo cancer models, KAI1 supplementation significantly inhibited tumor angiogenesis and growth. A peptide derived from the large extracellular loop of KAI1 has been shown to have anti-angiogenic effects to block the progression of breast cancer and retinal neovascularization in vivo. CONCLUSIONS: KAI1 from PC is a novel molecular regulator that counterbalances the effect of angiogenic factors.

Discovery of chemerin as the new chemoattractant of human mesenchymal stem cells.

BACKGROUND: The homing capacity of human mesenchymal stem cells (hMSCs) to the injured sites enables systemic administration of hMSCs in clinical practice. In reality, only a small proportion of MSCs are detected in the target tissue, which is a major bottleneck for MSC-based therapies. We still don't know the mechanism how MSCs are chemo-attracted to certain target organ and engrafted through trans-endothelial migration. In this study, we aimed to determine the mechanism how the circulating hMSCs home to the injured liver. METHODS AND RESULTS: When we compare the cytokine array between normal and injured mouse liver at 1-day thioacetamide (TAA)-treatment, we found that chemerin, CXCL2, and CXCL10 were higher in the injured liver than normal one. Among three, only chemerin was the chemoattractant of hMSCs in 2D- and 3D-migration assay. Analysis of the signal transduction pathways in hMSCs showed that chemerin activated the phosphorylation of JNK1/2, ERK1/2 and p38, and finally upregulated CD44, ITGA4, and MMP-2 that are involved in the transendothelial migration and extravasation of MSCs. Upstream transcription regulators of CD44, ITGA4, and MMP-2 after chemerin treatment were MZF1, GATA3, STAT3, and STAT5A. To develop chemerin as a chemoattractant tool, we cloned gene encoding the active chemerin under the CMV promoter (CMV-aChemerin). We analyzed the migration of hMSCs in the 3D model for space of the Disse, which mimics transmigration of hMSCs in the liver. CMV-aChemerin-transfected hepatocytes were more effective to attract hMSC than control hepatocytes, leading to the enhanced transendothelial migration and homing of hMSCs to liver. The homing efficiency of the intravascularly-delivered hMSCs to liver was evaluated after systemic introduction of the CMV-aChemerin plasmid packed in liposome-vitamin A conjugates which target liver. CMV-aChemerin plasmid targeting liver significantly enhanced homing efficiency of hMSCs to liver compared with control plasmid vector. CONCLUSIONS: Chemerin is the newly found chemoattractant of hMSCs and may be a useful tool to manipulate the homing of the intravascularly-administered hMSC to the specific target organ.

Endothelin-1 enhances the regenerative capability of human bone marrow-derived mesenchymal stem cells in a sciatic nerve injury mouse model.

We expanded the application of endothelin-1 (EDN1) by treating human mesenchymal stem cell (hMSC) organotypic spinal cord slice cultures with EDN1. EDN1-treated hMSCs significantly enhanced neuronal outgrowth. The underlying mechanism of this effect was evaluated via whole-genome methylation. EDN1 increased whole-genome demethylation and euchromatin. To observe demethylation downstream of EDN1, deaminases and glycosylases were screened, and APOBEC1 was found to cause global demethylation and OCT4 gene activation. The sequence of methyl-CpG-binding domain showed similar patterns between EDN1- and APOBEC1-induced demethylation. SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily A member 4 (SMARC A4) and SMARC subfamily D, member 2 (SMARC D2) were screened via methyl-CpG-binding domain sequencing as a modulator in response to EDN1. Chromatin immunoprecipitation of the H3K9me3, H3K27me3, and H3K4me4 binding sequences on the APOBEC1 promoter was analyzed following treatment with or without siSMARC A4 or siSMARC D2. The results suggested that SMARC A4 and SMARC D2 induced a transition from H3K9me3 to H3K4me3 in the APOBEC1 promoter region following EDN1 treatment. Correlations between EDN1 pathways and therapeutic efficacy in hBM-MSCs were determined in a sciatic nerve injury mouse model. Thus, EDN1 may be a useful novel-concept bioactive peptide and biomaterial component for improving hMSC regenerative capability.

Retinol from hepatic stellate cells via STRA6 induces lipogenesis on hepatocytes during fibrosis.

BACKGROUND: Hepatic stellate cells (HSCs) are activated in response to liver injury with TIF1γ-suppression, leading to liver fibrosis. Here, we examined the mechanism how reduction of TIF1γ in HSCs induces damage on hepatocytes and liver fibrosis. METHOD: Lrat:Cas9-ERT2:sgTif1γ mice were treated Tamoxifen (TMX) or wild-type mice were treated Thioacetamide (TAA). HSCs were isolated from mice liver and analyzed role of Tif1γ. HepG2 were treated retinol with/without siRNA for Stimulated by retinoic acid 6 (STRA6) or Retinoic acid receptor(RAR)-antagonist, and LX2 were treated siTIF1γ and/or siSTRA6. TAA treated mice were used for evaluation of siSTRA6 effect in liver fibrosis. RESULTS: When we blocked the Tif1γ in HSCs using Lrat:Cas9-ERT2:sgTif1γ mice, retinol is distributed into hepatocytes. Retinol influx was confirmed using HepG2, and the increased intracellular retinol led to the upregulation of lipogenesis-related-genes and triglyceride. This effect was inhibited by a RAR-antagonist or knock-down of STRA6. In the LX2, TIF1γ-suppression resulted in upregulation of STRA6 and retinol release, which was inhibited by STRA6 knock-down. The role of STRA6-mediated retinol transfer from HSCs to hepatocytes in liver fibrosis was demonstrated by in vivo experiments where blocking of STRA6 reduced fibrosis. CONCLUSIONS: Retinol from HSCs via STRA6 in response to injury with TIF1γ-reduction is taken up by hepatocytes via STRA6, leading to fat-deposition and damage, and liver fibrosis.

Nanoparticles suppress fluid instabilities in the thermal drawing of ultralong nanowires.

Ultra-long metal nanowires and their facile fabrication have been long sought after as they promise to offer substantial improvements of performance in numerous applications. However, ultra-long metal ultrafine/nanowires are beyond the capability of current manufacturing techniques, which impose limitations on their size and aspect ratio. Here we show that the limitations imposed by fluid instabilities with thermally drawn nanowires can be alleviated by adding tungsten carbide nanoparticles to the metal core to arrive at wire lengths more than 30 cm with diameters as low as 170 nm. The nanoparticles support thermal drawing in two ways, by increasing the viscosity of the metal and lowering the interfacial energy between the boron silicate and zinc phase. This mechanism of suppressing fluid instability by nanoparticles not only enables a scalable production of ultralong metal nanowires, but also serves for widespread applications in other fluid-related fields.

Novel Zinc / Tungsten Carbide Nanocomposite as Bioabsorbable Implant.

There is a lack of bioabsorbable materials with adequate mechanical strength suitable for implant applications that provide temporary support while tissue integrity is restored, especially for pediatric applications. Bioabsorbable metals have emerged as an attractive choice due to their combination of strength, ductility, and biocompatibility in vivo. Zinc has shown great promise as a bioabsorbable metal, but the weak mechanical properties of pure zinc limit its application as an implant material. This study investigates zinc-tungsten carbide (Zn-WC) nanocomposite as a novel material for bioabsorbable metallic implants. Ultrasound-assisted powder compaction was used to fabricate Zn-WC nanocomposites. This study includes the material characterization of microstructure, microhardness, and degradability. Results showed that tungsten carbide nanoparticles enhanced the mechanical properties of Zn, and maintained the favorable corrosion rate of pure Zn. These results encourage further investigation of Zn-WC nanocomposites for biomedical applications with the ultimate goal of creating safe and efficacious bioabsorbable metallic implants for many clinical applications.

Hepatic stellate cell-specific knockout of transcriptional intermediary factor 1γ aggravates liver fibrosis.

Transforming growth factor ß (TGFß) is a crucial factor in fibrosis, and transcriptional intermediary factor 1γ (TIF1γ) is a negative regulator of the TGFß pathway; however, its role in liver fibrosis is unknown. In this study, mesenchymal stem cells derived from human embryonic stem cells (hE-MSCs) that secrete hepatocyte growth factor (HGF) were used to observe the repair of thioacetamide (TAA)-induced liver fibrosis. Our results showed that TIF1γ was significantly decreased in LX2 cells when exposed to TGFß1. Such decrease of TIF1γ was significantly prevented by co-culture with hE-MSCs. Interaction of TIF1γ with SMAD2/3 and binding to the promoter of the α-smooth muscle gene (αSMA) suppressed αSMA expression. Phosphorylation of cAMP response element-binding protein (CREB) and binding on the TIF1γ promoter region induced TIF1γ expression. Furthermore, hepatic stellate cell-specific TIF1γ-knockout mice showed aggravation of liver fibrosis. In conclusion, loss of TIF1γ aggravates fibrosis, suggesting that a strategy to maintain TIF1γ during liver injury would be a promising therapeutic approach to prevent or reverse liver fibrosis.

The MicroRNA-92a/Sp1/MyoD Axis Regulates Hypoxic Stimulation of Myogenic Lineage Differentiation in Mouse Embryonic Stem Cells.

Hypoxic microenvironments exist in developing embryonic tissues and determine stem cell fate. We previously demonstrated that hypoxic priming plays roles in lineage commitment of embryonic stem cells. In the present study, we found that hypoxia-primed embryoid bodies (Hyp-EBs) efficiently differentiate into the myogenic lineage, resulting in the induction of the myogenic marker MyoD, which was not mediated by hypoxia-inducible factor 1α (HIF1α) or HIF2α, but rather by Sp1 induction and binding to the MyoD promoter. Knockdown of Sp1 in Hyp-EBs abrogated hypoxia-induced MyoD expression and myogenic differentiation. Importantly, in the cardiotoxin-muscle injury mice model, Hyp-EB transplantation facilitated muscle regeneration in vivo, whereas transplantation of Sp1-knockdown Hyp-EBs failed to do. Moreover, we compared microRNA (miRNA) expression profiles between EBs under normoxia versus hypoxia and found that hypoxia-mediated Sp1 induction was mediated by the suppression of miRNA-92a, which directly targeted the 3' untranslated region (3' UTR) of Sp1. Further, the inhibitory effect of miRNA-92a on Sp1 in luciferase assay was abolished by a point mutation in specific sequence in the Sp1 3' UTR that is required for the binding of miRNA-92a. Collectively, these results suggest that hypoxic priming enhances EB commitment to the myogenic lineage through miR-92a/Sp1/MyoD regulatory axis, suggesting a new pathway that promotes myogenic-lineage differentiation.

Toll-like receptor mediated inflammation requires FASN-dependent MYD88 palmitoylation.

Toll-like receptor (TLR)/myeloid differentiation primary response protein (MYD88) signaling aggravates sepsis by impairing neutrophil migration to infection sites. However, the role of intracellular fatty acids in TLR/MYD88 signaling is unclear. Here, inhibition of fatty acid synthase by C75 improved neutrophil chemotaxis and increased the survival of mice with sepsis in cecal ligation puncture and lipopolysaccharide-induced septic shock models. C75 specifically blocked TLR/MYD88 signaling in neutrophils. Treatment with GSK2194069 that targets a different domain of fatty acid synthase, did not block TLR signaling or MYD88 palmitoylation. De novo fatty acid synthesis and CD36-mediated exogenous fatty acid incorporation contributed to MYD88 palmitoylation. The binding of IRAK4 to the MYD88 intermediate domain and downstream signal activation required MYD88 palmitoylation at cysteine 113. MYD88 was palmitoylated by ZDHHC6, and ZDHHC6 knockdown decreased MYD88 palmitoylation and TLR/MYD88 activation upon lipopolysaccharide stimulus. Thus, intracellular saturated fatty acid-dependent palmitoylation of MYD88 by ZDHHC6 is a therapeutic target of sepsis.

Endothelin-1 Augments Therapeutic Potency of Human Mesenchymal Stem Cells via CDH2 and VEGF Signaling.

In our previous study, we identified differences in the levels of CDH2 and vascular endothelial growth factor (VEGF) between effective and ineffective clones of human umbilical cord blood (hUCB) mesenchymal stem cells (MSCs), with regard to the infarcted rat myocardium. In this study, we compared gene expression profiles between the effective and ineffective clones and identified that endothelin-1 (EDN1) is enriched in the effective clone. In the mechanistic analyses, EDN1 significantly increased expression of CDH2 and VEGF through endothelin receptor A (EDNRA), which was prevented by EDNRA blocker, BQ123. To decipher how EDN1 induced gene expression of CDH2, we performed a promoter activity assay and identified GATA2 and MZF1 as inducers of CDH2. EDN1 significantly enhanced the promoter activity of the CDH2 gene, which was obliterated by the deletion or point mutation at GATA2 or MZF1 binding sequence. Next, therapeutic efficacy of EDN1-priming of hUCB-MSCs was tested in a rat myocardial infarction (MI) model. EDN1-primed MSCs were superior to naive MSCs at 8 weeks after MI in improving myocardial contractility (p < 0.05), reducing fibrosis area (p < 0.05), increasing engraftment efficiency (p < 0.05), and improving capillary density (p < 0.05). In conclusion, EDN1 induces CDH2 and VEGF expression in hUCB-MSCs, leading to the improved therapeutic efficacy in rat MI, suggesting that EDN1 is a potential priming agent for MSCs in regenerative medicine.

Hepatocyte Growth Factor Improves the Therapeutic Efficacy of Human Bone Marrow Mesenchymal Stem Cells via RAD51.

Human embryonic stem cell-derived mesenchymal stem cells (hE-MSCs) have greater proliferative capacity than other human mesenchymal stem cells (hMSCs), suggesting that they may have wider applications in regenerative cellular therapy. In this study, to uncover the anti-senescence mechanism in hE-MSCs, we compared hE-MSCs with adult bone marrow (hBM-MSCs) and found that hepatocyte growth factor (HGF) was more abundantly expressed in hE-MSCs than in hBM-MSCs and that it induced the transcription of RAD51 and facilitated its SUMOylation at K70. RAD51 induction/modification by HGF not only increased telomere length but also increased mtDNA replication, leading to increased ATP generation. Moreover, HGF-treated hBM-MSCs showed significantly better therapeutic efficacy than naive hBM-MSCs. Together, the data suggest that the RAD51-mediated effects of HGF prevent hMSC senescence by promoting telomere lengthening and inducing mtDNA replication and function, which opens the prospect of developing novel therapies for liver disease.

Atorvastatin prevents endothelial dysfunction in high glucose condition through Skp2-mediated degradation of FOXO1 and ICAM-1.

OBJECTIVE: The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin has been reported to exert vasculo-protective action in diabetes. We investigated the vasculo-protective mechanism of atorvastatin by evaluating its effect on two major pathogenic molecules, FOXO1 and ICAM1, mediated by S-phase kinase-associated protein 2 (Skp2) in diabetic endothelial dysfunction. APPROACH AND RESULTS: [1] FOXO1: Hyperglycemic condition increased FOXO1 protein level in endothelial cells, which was reversed by atorvastatin. This atorvastatin effect was obliterated by treatment of protease inhibitor, suggesting that atorvastatin induces degradation of FOXO1. Immunoprecipitation showed that atorvastatin facilitated the binding of Skp2 to FOXO1, leading to ubiquitination and degradation of FOXO1. [2] ICAM-1: Increased ICAM1 in high glucose condition was reduced by atorvastatin. But this effect of atorvastatin was obliterated when Skp2 was inhibited, suggesting that atorvastatin enhances binding of Skp2 to ICAM1 leading to degradation. Actually, ubiquitination and degradation of ICAM-1 were reduced when Skp2 was inhibited. In vitro monocyte adhesion assay revealed that atorvastatin reduced monocyte adhesion on endothelial cells in high glucose condition, which was reversed by Skp2 knock-down. CONCLUSION: Atorvastatin strengthens Skp2 binding to FOXO1 or ICAM1, leading to ubiquitination and degradation. Skp2-dependent ubiquitination of major pathogenic molecules is the key mechanism for statin's protective effect on endothelial function in diabetes.

Stretching Micro Metal Particles into Uniformly Dispersed and Sized Nanoparticles in Polymer.

There is a longstanding challenge to disperse metal nanoparticles uniformly in bulk polymers for widespread applications. Conventional scale-down techniques often are only able to shrink larger elements (such as microparticles and microfibers) into micro/nano-elements (i.e. nanoparticles and nanofibers) without much altering their relative spatial and size distributions. Here we show an unusual phenomenon that tin (Sn) microparticles with both poor size distribution and spatial dispersion were stretched into uniformly dispersed and sized Sn nanoparticles in polyethersulfone (PES) through a stack and draw technique in thermal drawing. It is believed that the capillary instability plays a crucial role during thermal drawing. This novel, inexpensive, and scalable method overcomes the longstanding challenge to produce bulk polymer-metal nanocomposites (PMNCs) with a uniform dispersion of metallic nano-elements.