Improvement in ORR Durability of Fe Single-Atom Carbon Catalysts Hybridized with CeO2 Nanozyme.

FeNC catalysts are considered one of the most promising alternatives to platinum group metals for the oxygen reduction reaction (ORR). Despite the extensive research on improving ORR activity, the undesirable durability of FeNC is still a critical issue for its practical application. Herein, inspired by the antioxidant mechanism of natural enzymes, CeO2 nanozymes featuring catalase-like and superoxide dismutase-like activities were coupled with FeNC to mitigate the attack of reactive oxygen species (ROS) for improving durability. Benefiting from the multienzyme-like activities of CeO2, ROS generated from FeNC is instantaneously eliminated to alleviate the corrosion of carbon and demetallization of metal sites. Consequently, FeNC/CeO2 exhibits better ORR durability with a decay of only 5 mV compared to FeNC (18 mV) in neutral electrolyte after 10k cycles. The FeNC/CeO2-based zinc-air battery also shows minimal voltage decay over 140 h in galvanostatic discharge-charge cycling tests, outperforming FeNC and commercial Pt/C.

Grain-Boundary-Rich Ceria Metallene Nanozyme with Abundant Metal Site Pairs Boosts Phosphatase-like Activity.

Natural phosphatases featuring paired metal sites inspire various advanced nanozymes with phosphatase-like activity as alternatives in practical applications. Numerous efforts to create point defects show limited metal site pairs, further resulting in insufficient activity. However, it remains a grand challenge to accurately engineer abundant metal site pairs in nanozymes. Herein, we report a grain-boundary-rich ceria metallene nanozyme (GB-CeO2) with phosphatase-like activity. Grain boundaries acting as the line or interfacial defects can effectively increase the content of Ce4+/Ce3+ site pairs to 72.28%, achieving a 49.28-fold enhancement in activity. Furthermore, abundant grain boundaries optimize the band structure to assist the photoelectron transfer under irradiation, which further increases the content of metal site pairs to 88.96% and finally realizes a 114.39-fold enhanced activity over that of CeO2 without irradiation. Given the different inhibition effects of pesticides on catalysts with and without irradiation, GB-CeO2 was successfully applied to recognize mixed toxic pesticides.

Sub-diffraction optical beam lithography based on a center-non-zero depletion laser.

Photoinhibition (PI) mechanisms have been introduced in nanofabrication which allows breaking the diffraction limit by large factors. Donut-shaped laser is usually selected as a depletion beam to reduce linewidth, but the parasitic process has made the results of the experiment less than expected. As a result, the linewidth is difficult to achieve below 50 nm with 780 nm femtosecond and 532 nm continuous-wave lasers. Here, we propose a new, to the best of our knowledge, method based on a center-non-zero (CNZ) depletion laser to further reduce linewidth. By constructing a smaller zone of action under the condition of keeping the maximum depletion intensity constant, a minimum linewidth of 30 nm (λ / 26) was achieved. Two ways to construct CNZ spots were discussed and experimented, and the results show the advantages of our method to reduce the parasitic process to further improve the writing resolution.

Bridged Pt-OH-Mn Mediator in N-coordinated Mn Single Atoms and Pt Nanoparticles for Electrochemical Biomolecule Oxidation and Discrimination.

The rational design of efficient catalysts for uric acid (UA) electrooxidation, as well as the establishment of structure-activity relationships, remains a critical bottleneck in the field of electrochemical sensing. To address these challenges, herein, a hybrid catalyst that integrates carbon-supported Pt nanoparticles and nitrogen-coordinated Mn single atoms (PtNPs/MnNC) is developed. The metal-metal interaction during annealing affords the construction of metallic-bonded Pt-Mn pairs between PtNPs and Mn single atoms, facilitating the electron transfer from PtNPs to the support and thereby optimizing the electronic structure of catalysts. More importantly, experiments and theoretical calculations provide visual proof for the 'incipient hydrous oxide adatom mediator' mechanism for UA oxidation. The Pt-Mn pairs first adsorb OH* to construct the bridged Pt-OH-Mn mediators to serve as a highly active intermediate for N-H bond dissociation and proton transfer. Benefiting from the unique electronic and geometric structure of the catalytic center and reactive intermediates, PtNPs/MnNC exhibits superior electrooxidation performance. The electrochemical sensor based on PtNPs/MnNC enables sensitive detection and discrimination of UA and dopamine in serum samples. This work offers new insights into the construction of novel electrocatalysts for sensitive sensing platforms.

Harmonizing Enzyme-like Cofactors to Boost Nanozyme Catalysis.

Engineering isolated metal sites resembling the primary coordination sphere of metallocofactors enables atomically dispersed materials as promising nanozymes. However, most existing nanozymes primarily focus on replicating specific metallocofactors while neglecting other supporting cofactors within active pockets, leading to reduced electron transfer (ET) efficiency and thus inferior catalytic performances. Herein, we report a metal-organic framework UiO-67 nanozyme with atomically dispersed iron sites, which involves multiple tailored enzyme-like nanocofactors that synergistically drive the ET process for enhanced peroxidase-like catalysis. Among them, the linker-coupled atomic iron site plays a critical role in substrate activation, while bare linkers and zirconia nodes facilitate the ET efficiency of intermediates. The synergy of three nanocofactors results in a 4.29-fold enhancement compared with the single effort of isolated metal site-based nanocofactor, holding promise in immunoassay for sensitive detection of chlorpyrifos. This finding opens a new way for designing high-performance nanozymes by harmonizing various nanocofactors at the atomic and molecular scale.

Effect of indomethacin and lactoferrin on human tenocyte proliferation and collagen formation in vitro.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in patients with injuries and inflammation of tendon and ligament, and as post-surgical analgesics. The aim of this study is to investigate the effect of indomethacin, a classic NSAID and its combinational effect with an anabolic agent of skeletal tissue, lactoferrin, on the proliferation and collagen formation of human tenocytes in vitro. A factorial experimental design was employed to study the dose-dependent effect of the combination of indomethacin and lactoferrin. The results showed that indomethacin at high concentration (100 µM) inhibited human tenocyte proliferation in culture medium with 1-10% fetal bovine serum (FBS) in vitro. Also, high dose of indomethacin inhibited the collagen formation of human tenocytes in 1% FBS culture medium. Lactoferrin at 50-100 µg/ml promoted human tenocyte survival in serum-free culture medium and enhanced proliferation and collagen synthesis of human tenocytes in 1% FBS culture medium. When 50-100 µg/ml lactoferrin was used in combination with 100-200 µM indomethacin, it partially rescued the inhibitory effects of indomethacin on human tenocyte proliferation, viability and collagen formation. To our knowledge, it is the first evidence that lactoferrin is anabolic to human tenocytes in vitro and reverses potential inhibitory effects of NSAIDs on human tenocytes.

Light and matter co-confined multi-photon lithography.

Mask-free multi-photon lithography enables the fabrication of arbitrary nanostructures low cost and more accessible than conventional lithography. A major challenge for multi-photon lithography is to achieve ultra-high precision and desirable lateral resolution due to the inevitable optical diffraction barrier and proximity effect. Here, we show a strategy, light and matter co-confined multi-photon lithography, to overcome the issues via combining photo-inhibition and chemical quenchers. We deeply explore the quenching mechanism and photoinhibition mechanism for light and matter co-confined multiphoton lithography. Besides, mathematical modeling helps us better understand that the synergy of quencher and photo-inhibition can gain a narrowest distribution of free radicals. By using light and matter co-confined multiphoton lithography, we gain a 30 nm critical dimension and 100 nm lateral resolution, which further decrease the gap with conventional lithography.

Development of a refined tenocyte differentiation culture technique for tendon tissue engineering.

We have established that human tenocytes can differentiate in the absence of exogenous fetal bovine serum (FBS) but in the presence of insulin-like growth factor-1 (IGF-1) and transforming growth factor-ß3 (TGF-ß3). The extent of tenocyte differentiation was assessed by examining cell survival, collagen synthesis, cell morphology and expression of tenocyte differentiation markers such as scleraxis (Scx), tenomodulin (Tnmd), collagen type I (Col-I) and decorin (Dcn). Our results indicate that 50 ng/ml IGF-1 and 10 ng/ml TGF-ß3 (in the absence of FBS) were capable of maintaining in vitro human tenocyte survival in 14-day cultures. The extent of collagen synthesis and messenger ribonucleic acid expression of Scx, Tnmd, Col-I and Dcn were significantly upregulated in response to IGF-1 and TGF-ß3. These findings have shown for the first time that human tenocytes can be maintained in long-term culture, in serum-free conditions, making this approach a suitable one for the purpose of tendon tissue engineering.

[The effects of insulin-like growth factor 1 and transforming growth factor ß-3 at various concentration on tenocyte survival and collagen formation].

OBJECTIVE: To optimize the culture media by adding the growth factors required to maintain tenocytes survival and promote their differentiation without fetal bovine serum (FBS) supplementation, in order for the approach to be used for any future tendon tissue engineering. METHODS: The human tenocytes were cultured in α-MEM media by adding FBS at various concentrations and supplementing both insulin-like growth factor 1 (IGF-1) and transforming growth factor ß-3 (TGFß-3). A number of growth factors were selected that could support tenocytes expansion at reduced differentiated state with the minimum FBS. By employing fractional factorial design, different treatment groups went through AlamarBlue(TM) tests to evaluate the cell number growth whilst collagen quantification by real time RT-PCR technique and tenocyte differentiation were also studied. RESULTS: The tenocytes cultured for 14 days with 0% FBS, 50 ng/ml IGF-1 and 10 ng/ml TGFß-3 maintained survival over 14 days, the Cell count were 6228.68 ± 43.87. They were higher than the other experimental groups, but less than 10% FBS control group (13 576.74 ± 286.75, t = 41.29, P < 0.05). The tenocytes cultured in the treated group also showed enhanced collagen synthesis ((0.322 ± 0.003) ng, t = 4.13 - 5.93, P < 0.05). CONCLUSION: These findings have shown for the first time that human tenocytes could be maintained survival for a long period of time in the culture media without FBS, having this approach a suitable one for tendon tissue engineering.

Dip-In Photoresist for Photoinhibited Two-Photon Lithography to Realize High-Precision Direct Laser Writing on Wafer.

For decades, photoinhibited two-photon lithography (PI-TPL) has been continually developed and applied into versatile nanofabrication. However, ultrahigh precision fabrication on wafer by PI-TPL remains challenging, due to the lack of a refractive index (n) matched photoresist (Rim-P) with effective photoinhibition capacity for dip-in mode. In this paper, various Rim-P are developed and then screened for their applications in PI-TPL. In addition, different lithography methods (in terms of oil-mode and dip-in mode) are analyzed by use of optical simulations combined with experiments. Remarkably, one type of Rim-P (n = 1.518) shows effective photoinhibition capacity, which represents an outstanding breakthrough in the field of PI-TPL. In contrast to photoresist with an unsuitable refractive index, optical aberrations are almost completely eliminated in the dip-in mode by using the Rim-P. Consequently, features with a minimum critical dimension as small as 39 nm are successfully achieved on wafer by dip-in PI-TPL, which paves the way for subdiffraction silicon-based chip manufacturing by PI-TPL. Moreover, through a combination of the Rim-P and dip-in mode, the ability to achieve tall and high-precision three-dimensional nanostructures is no longer problematic.

In vitro two-dimensional and three-dimensional tenocyte culture for tendon tissue engineering.

In order to examine the differentiation potential of the tenocytes expanded in our defined culture medium (reported previously) and the effect of sequential combination of the two culture conditions on human tenocytes, a two-dimensional and three-dimensional experimental approach was used. Human tenocytes were sequentially exposed to 1% fetal bovine serum (FBS) + 50 ng/ml platelet-derived growth factor-BB (PDGFBB ) + 50 ng/ml basic fibroblast growth factor (bFGF) for the first 14 days (expansion phase) followed by a further 14-day culture in the presence of 10 ng/ml transforming growth factor ß-3 plus 50 ng/ml insulin-like growth factor 1, but in the absence of serum (differentiation phase). The results showed that by sequential treatment of human tenocytes maintaining a long-term two-dimensional tenocyte culture in vitro for up to 28 days was possible. These findings were further verified using a three-dimensional scaffold (Bombyx silk) whereby the tendon-like constructs formed resembled macroscopically and microscopically the constructs formed in 10% FBS supplemented culture media and the human hamstring tendon. These findings were further substantiated using haematoxylin and eosin staining, scanning electron microscopy and by immunohistochemical detection of type I collagen. In addition, the mechanical properties of the three-dimensional constructs were determined to be significantly superior to that of the natural human hamstring tendon. This is the first report to demonstrate a possible approach in expanding and differentiating human tenocytes for tendon tissue engineering.

The study of threshold determination of gene identification and its improvement algorithms.

The problem of gene recognition based on the ratio of power spectrum, SNR, and Gabor transform and its implementation of the calculation were discussed. The optimal threshold could guarantee to identify the DNA sequences with the signal-to-noise ratio. It summarized three kinds of traditional ways to determine the threshold, and advanced the optimum entitled method showing the disparate degrees of highlight and the discrimination rate method of the exons or introns as far as possible to improve the rate of their accuracy. To evaluate different determination methods of threshold by using the calculation results of four kinds of DNA sequence. In order to ensure the analysis of DNA sequence more accurate, it adopted and improved gene identification method of Fourier transformation in a short time which is based on Gabor transformation. By using of the ergodic theory, the fixed percentage of the sequence length of exons in DNA has been improved to be the dynamic percentages which focus on different gene types. The exons of the DNA sequence which have been already discovered were identified by using the improved algorithm. With comparison of the results and the actual endpoint of exons, it confirmed that the improved algorithm can figure out the endpoint of the exons more accurate.

Development of a refined tenocyte expansion culture technique for tendon tissue engineering.

The aim of this study was to efficiently expand less differentiated tenocytes with minimum use of fetal bovine serum (FBS) for tenocyte-based tendon tissue engineering. To achieve this goal, human tenocytes were cultured in different concentrations of FBS and combinations of growth factors PDGF(BB), IGF-1 and bFGF. A number of growth factors were selected that could support tenocyte expansion at reduced differentiated state with minimum FBS usage. Results showed that the expansion of the tenocytes cultured for 14 days with 1% FBS, 50 ng/ml PDGF(BB) and 50 ng/ml bFGF was similar to that cultured in the 10% FBS control group. The tenocytes cultured in the treatment group showed significantly lower collagen synthesis and down-regulation of mRNA expression of tendon differentiation markers. Cell morphology confirmed that tenocytes cultured in the growth factors had reduced collagen fibril formation compared to tenocytes cultured in 10% FBS. Our findings confirm the feasibility of inducing human tenocyte expansion in vitro with the least amount of FBS usage, while controlling their differentiation until required.

Is hyponatremia mistreated? Challenging the current paradigm.

BACKGROUND: Hyponatremia is a common but often mistreated clinical situation in the ICU. This often requires the physician to identify the underlying problem, adrenal insufficiency. However, by the textbook, the current treatment always involves sodium chloride supplementation to hyponatremic patients, either intravenous or oral intake. We hypothesize that the mechanism behind most hyponatremia is most likely to be the sodium and water redistribution from the serum to the cells or the interstitial spaces due to the insufficient cortical steroid, not the sodium deficiency. As we have no reason to believe the patients have lost that much sodium which caused hyponatremia. Therefore, giving this type of hyponatremic patients (adrenal insufficient) sodium chloride is always ineffective and sometimes catastrophic. METHODS: We discuss the possible mechanism for hyponatremia in critically ill/post surgery patients who are mostly likely to be adrenal insufficient rather than absolute sodium deficiency. In combination with many other common but unexplainable symptoms such as nausea, vomiting, obstinate diarrhea, hypotension and coma in the ICU, it is highly likely that hyponatremia is a condition which reflects the patients' adrenal function. The evidence supporting our hypothesis is that, (1) the serum sodium level does not always respond well to sodium supplementation therapy; (2) those aforementioned symptoms alleviated simultaneously with the serum sodium level returned to normal after the hydrocortisone or prednisone was administered without any oral/intravenous sodium supplementation; (3) patient with an elevated serum/urine cortisol level suffers from aforementioned unexplainable symptoms does not warrant him being adrenal sufficient. If the patient also has hyponatremia, the diagnosis can be considered as "relative adrenal insufficiency" and the patient would respond well to hydrocortisone or prednisone therapy. CONCLUSIONS: We hypothesize that hyponatremia without significant loss of sodium can be used as an indicator to monitor the patients' adrenal function regardless of the serum/urine cortisol level. Furthermore, we propose a novel approach toward hyponatremia treatment in critically ill patients would be hydrocortisone or prednisone therapy depending on the circumstances.

Proliferation and differentiation of human tenocytes in response to platelet rich plasma: an in vitro and in vivo study.

Platelet rich plasma (PRP) is the autologous plasma fraction with a platelet-rich cellular component which is enriched with a number of growth factors. Due to its availability and low cost, PRP has become an increasingly popular clinical tool as an alternative source of growth factors for various applications, for example, tendon regeneration but with limited success in clinical trials. The main objective of the current study was to determine whether activated PRP [i.e., platelet rich plasma-clot release (PRCR)] could be used to induce the proliferation and collagen synthesis in human tenocyte in vitro. The advantage of using PRCR is that the platelet-derived bioactive factors are more concentrated and could initiate a more rapid and accelerated healing response than PRP. Our results demonstrated that 10% PRCR treatment accelerated the extent of cell proliferation and collagen production by human tenocytes in vitro. The expression of specific tenocyte markers were similar to conventional fetal bovine serum (FBS)-treated tenocytes implanted in mice within 14 days of implantation in diffusion chambers. Moreover, relatively more collagen fibrils were evident in PRCR-treated tenocytes in vivo as compared to 10% FBS-treated cells. Overall, our feasibility study has indicated that PRCR can induce human tenocyte proliferation and collagen synthesis which could be implemented for future tendon regeneration in reconstructive surgeries.

Improved human tenocyte proliferation and differentiation in vitro by optimized silk degumming.

Tendon disorders are common clinical conditions. Tendon tissue engineering provides a new approach for tendon repair by integrating engineered substitutes with their native counterparts. Silk is considered to be a promising candidate for tendon engineering because of its biological and mechanical properties. However, a major concern with using silk for biomedical applications is the immune responses generated by sericin, a glue-like protein that coats the silk fibres. This study improves the existing protocols for silk 'degumming' which removes sericin and enables preparation of silk that is suitable for tendon regeneration. Bombyx mori silks were treated by sequential treatments with different proteases. The efficiency of degumming was determined by measuring weight loss, picric acid and carmine staining and scanning electron microscopy. To evaluate the cellular responses after degumming, the growth and differentiation of human tenocytes on silks were examined. The results showed that sequential protease treatment effectively degummed raw silks. The sequentially degummed silks showed enhanced tenocyte proliferation and upregulated mRNA levels of tendon markers. Thick cell multilayers formed on the treated silks, with cells and collagen fibres penetrating into the spaces in individual silk filaments, resulting in a structure resembling human tendon.