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Graphical abstract Highlights • Novel carbon dots are synthesized using Enteromorpha prolifera as raw materials. • Dual fluorescence emission in the visible and near-infrared range is achieved. • The fluorescence is inert to phenols but sensitive to their oxidation products. • The radical scavenging processes of natural phenols are able to be detected. Abstract Phenolic compounds can act as protective agents against free radical oxidation. It is desirable to develop simple and efficient analytical techniques to measure the phenolic content and their antioxidant capacity. Using Enteromorpha prolifera (EP) as the carbon source, novel fluorescent carbon dots (EP-CDs) were synthesized through a facile microwave-assisted hydrothermal method. EP-CDs exhibit high mono-dispersity in aqueous solution, low cytotoxicity, and dual fluorescence emission in the visible and near-infrared range. The fluorescence of EP-CDs is inert to phenolic compounds and hydroxyl free radicals, but could be rapidly and efficiently quenched by the quinoid oxidation products. By monitoring the fluorescence quenching of EP-CDs, it is demonstrated that the radical scavenging processes of different natural phenolic compounds could be sensitively detected. By employing this eco-friendly and economic analytical method, phenols with different structure or concentration could be rapidly detected and determined. EP-CDs also have potential for additional applications, such as hydrogen peroxide and iron analysis. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) has been widely applied for orthopedic and oral implants due to its excellent mechanical properties, biocompatibility, and radiolucency. However, its bioinert and the lack of anti-microbial activity limit its application. We modified the PEEK surface with Ta/Cu co-implantation using plasma immersion ion-implantation technology. After implantation of Ta/Cu ions, the morphology and roughness of the PEEK surface were not significantly changed at micron level. We estimated the cytocompatibility, anti-microbial ability, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs) of the modified surfaces in vitro. Compared to the untreated surfaces, the Ta ion-treated surface showed improved adhesion, proliferation, ALP activity, ECM mineralization, and osteogenic gene expression of BMSCs. Further, the Cu ion-treated surface showed reduced initial adhesion and proliferation of Escherichia coli and Staphylococcus aureus in vitro and proliferation of Staphylococcus aureus in the mouse subcutaneous implant-associated infection model. According to a rat bone repair model, all Ta ion-implanted groups demonstrated improved new bone formation. In summary, Ta/Cu ion co-impanation improved anti-microbial activity and promoted osseointegration of the PEEK surface. • Cu and Ta nanoparticles were incorporated on PEEK surface by ion implantation. • Ta/Cu co-impanted PEEK showed improved anti-microbial activity in vitro and in vivo. • Ta/Cu co-impanted PEEK exhibited enhanced cytocompatibility and osseointegration. [ABSTRACT FROM AUTHOR]

For the preparation of carbon dots (CDs), a variety of carbon sources and synthetic protocols are available which endow CDs with variable and unpredictable properties. In the present study, three CDs were developed with ionic liquid 1-butyl-3-methylimidazolium dicyanamide as the precursor through ethanol-thermal and hydrothermal strategies, termed as E-CDs and H-CDs, respectively. The features of these carbon dots, i.e., their physicochemical and optical properties, their interactions with bovine serum albumin (BSA) as well as their imaging capability were investigated with respect to the CDs prepared with microwave assisted approach (W-CDs). E-CDs and H-CDs were demonstrated to exhibit similar framework structures and optical properties, and they exhibited larger particle-sizes than that of W-CDs. In addition, the increase of ethanol-thermal and hydrothermal reaction time strengthened the quantum yields of the CDs and promoted their binding capability with BSA. E-CDs and H-CDs showed similar cytotoxicity on normal (LX-2) and cancer (SK-Hep-1) cells. We further found that these CDs may readily enter the cells within 5 min, while the fluorescence of hydrophilic E-CDs and H-CDs was very weak with respect to that of hydrophobic W-CDs in cell imaging. On the other hand, all the CDs exhibited little impact on the level of intracellular reactive oxygen species. The present study is conducive to guide the preparation of suitable carbon dots for different application scenarios. [Display omitted] • BmimDCN was used as precursor to prepare CDs through solvothermal methods. • Ethanol solvent and increased reaction time promoted QYs of CDs and binding to BSA. • CDs showed similar cytotoxicity on liver normal and cancer cells. • CDs had little impact on the level of intracellular ROS. • The cancer cells could take up the CDs within 5 min, and emitted weak fluorescence. [ABSTRACT FROM AUTHOR]

This study demonstrates that ligand-modified graphene quantum dots (GQDs) facilitate the simultaneous operation of multiple tasks without the need for external dyes. These tasks include selective cell labeling, targeted drug delivery, and real-time monitoring of cellular uptake. Folic acid (FA)-conjugated GQDs are synthesized and utilized to load the antitumor drug doxorubicin (DOX). The fabricated nanoassembly can unambiguously discriminate cancer cells from normal cells and efficiently deliver the drug to targeted cells. The inherent stable fluorescence of GQDs enables real-time monitoring of the cellular uptake of the DOX–GQD–FA nanoassembly and the consequent release of drugs. The nanoassembly is specifically internalized rapidly by HeLa cells via receptor-mediated endocytosis, whereas DOX release and accumulation are prolonged. In vitro toxicity data suggest that the DOX–GQD–FA nanoassembly can target HeLa cells differentially and efficiently while exhibiting significantly reduced cytotoxicity to non-target cells. [ABSTRACT FROM AUTHOR]

Abstract: A novel zwitterionic polypeptide derivative, denoted as His-PAsp/PAsp, was successfully synthesized by amidation of Poly (α,β-l-aspartic acid) with l-histidine methyl ester. Turbidity, zeta potential and 1H NMR measurements were used to study the aggregation behaviors of His-PAsp/PAsp under different pH values. The modified polypeptide derivative composed of electro-negatively carboxylic and electro-positively imidazole residues randomly so as to bear opposite charges at pH values above or below the isoelectric point. When the zwitterionic polypeptide was coated on silicon wafer as a model substrate material, the absorption resistance of fibrinogen, a blood protein resulting in the blood coagulation cascade, on the coated surface was measured. It was found that the adsorption amount of fibrinogen on the polypeptide-coated surface depended on the dose of the polypeptide on silicon wafer. Obvious resistance of the fibrinogen adsorption on the polypeptide-coated surface was observed. Since its good biodegradability and superior anti-protein-fouling property, this pH-responsive zwitterionic polypeptide is a promising candidate for surface modification in many biomedical applications, including medical implants, drug delivery carriers, and biosensors. [Copyright &y& Elsevier]

Abstract: Selective elution of components was visually observed on a mixture of lipids (ceramide III, palmitic acid, and cholesterol) as a mimicry of stratum corneum (SC) which was melted and sandwiched between glass plates. The lipid membrane was exposed to an aqueous solution of sodium dodecyl sulphate (SDS) and observed by an optical microscope. The contact of the lipid membrane with a SDS solution caused the elution of the lipid component as “myelin-form”, and the lipid membrane changed to a sponge structure. An infrared absorption spectroscopic study revealed that the SDS penetrated into the lipid mixture, and the fraction of ceramide in the sponge phase became higher than that in the lipid membrane before SDS treatment. The selective elution behaviour was confirmed by observing the behaviour of each component in lipid membrane by means of a fluorescence-staining method: The cholesterol was eluted with producing visual myelin-form on the contact with a SDS solution, and the following elution of palmitic acid occurred without myelin-form, while the ceramide III resisted the exposure to the SDS solution. These results are valid to elucidate the influence of surfactants on SC. [ABSTRACT FROM AUTHOR]

Abstract: Lipid mixtures consisting of ceramide III, palmitic acid, and cholesterol were prepared at different thermal and humidity conditions. The lipid mixture, treated at temperature higher than 100°C, displayed the similar thermal character to native human Stratum Corneum (SC), although hydration changed structural characters of the lipid mixtures as well as human SC: Hydration gave rise to the variation of lamellar distances in lipid mixtures such as lengthening of vertical repeat distance and slight-shortening of the lateral repeat distance. It also generated the configurational transition of amide groups. Since these variations depending on the heating and hydrating processes do not occur on pristine lipids, it can be confirmed that the lipid mixture forms hybrid phases by the association between heterogeneous lipids. [Copyright &y& Elsevier]

[Display omitted] • [Ch][Bit] and [Ch][Dhc] changed the natural structure of BSA. • The esterase-like activity of BSA decreased after adding [Ch][Br] and [Ch][I]. • The order of cytotoxicity: [Ch][Dhc] < [Ch][Bit] < [Ch][I] < [Ch][Br] < [Ch][Cl]. Choline-based ionic liquids (ILs) have been widely applied because of their good biocompatibility. Herein, the toxicity of choline-based ILs containing different anions was studied by UV–vis absorption spectra, fluorescence spectra, MTT assays and antibacterial experiments. The results explained that choline chloride ([Ch][Cl]) had no obvious effect on the conformation of bovine serum albumin (BSA), while the conformation could be slightly changed by choline bromide ([Ch][Br]). In the presence of choline iodide ([Ch][I]), choline bitartrate ([Ch][Bit]) and choline dihydrogen citrate ([Ch][Dhc]), the conformation of BSA changed significantly. The quenching mechanisms of [Ch][Bit] and [Ch][Dhc] were static quenching procedure, while there were charge transfer quenching and static quenching for [Ch][I]. ILs combined with BSA in spontaneous manner driven by hydrogen bond and van der Waals force, which was proved by thermodynamic constants and molecular docking. The toxicity of the five ILs to mammalian cells and bacteria came to a similar conclusion. [Ch][Cl] had little toxicity to cells, which was less than [Ch][Br] and [Ch][I]. [Ch][Bit] and [Ch][Dhc] were more toxic. These results provide more information to understand the effect of anions on choline-based ILs, in order to find low toxic choline-based ILs that can be used in biological and pharmaceutical fields. [ABSTRACT FROM AUTHOR]

Magnesium lithospermate B (MLB) is an active polyphenol acid with multiple pharmacological activities and poor oral bioavailability. The present research aimed to construct MLB loaded solid lipid nanoparticles (MLB-SLNs) for oral delivery to enhance its bioavailability. MLB-SLNs were prepared by solvent diffusion method and subsequently modified with polyethylene glycol monostearate (PEG-SA) superficially. The particle sizes of MLB-SLNs varied from 82.57 to 53.50 nm with an improved drug loading capacity (up to 16.18%) after PEG-SA modification. Pharmacokinetic study indicated that C max (peak plasma MLB concentration) and AUC (area under curve) of MLB-SLNs increased significantly compared to that of MLB solution in male SD rats. The relative bioavailability of MLB-SLNs with PEG-SA modification was 753.98% compared to MLB solution administered by tail intravenous injection. The enhanced transport mechanism could be further illustrated by the results that MLB-SLNs showed higher permeability across Madin-Daby canine kidney (MDCK) epithelial cell monolayer and MLB-SLNs with smaller particle size distribution and PEG-SA modification manifested stronger cellular internalization ability on MDCK cells. Thus, PEG-SA modified solid lipid nanoparticles confirmed with enhanced cellular transport and improved oral bioavailability can be a promising oral MLB delivery system. [ABSTRACT FROM AUTHOR]

Commercially available polystyrene (PS) fluorescent microspheres are widely used in biological field for tracing, in vivo imaging and calibration of flow cytometry, among other applications. However, these particles do suffer from some drawbacks such as the leakage and photobleaching of organic dyes within them. In the present study, inherently fluorescent properties of PS based microspheres have been explored for the first time. Here we find that a simple chloromethylation reaction endows the polystyrene particles with inherent fluorescence without any subsequent conjugation of an external fluorophore. A possible mechanism for fluorescence is elucidated by synthesizing and investigating p -ethylbenzyl chloride, a compound with similar structure. Significantly, no photobleaching or leaking issues were observed owing to the stable structure of the microspheres. Chloromethylated PS (CMPS) microspheres can keep their perpetual blue fluorescence even in dry powder state making them attractive as a potential coating material. Furthermore, the chloromethyl groups on CMPS microspheres make them very convenient for further functionalization. Poly(ethylene glycol) (PEG) grafted microspheres showed good biocompatibility and negligible cytotoxicity, and could be used to image intracellular Fe 3+ due to the selective fluorescence quenching effect of aqueous Fe 3+ in cytoplasm. [ABSTRACT FROM AUTHOR]

In an effort to prove the inherent side effects of doxorubicin (DOX) and potentially revoke the effects of drug resistance exhibited by cancer cells, we have designed a multifunctional DOX-delivery nano-carrier system able to encapsulate the drug resistance reversal agent Verapamil HCl (VRP·HCl). Hydrophilic short-chain polyethylene glycol (i.e., mPEG) was covalently linked to hydrophobic DOX and a benzoic imine linkage was used to form a linear amphiphilic PEGylated prodrug, namely mPEG- b -DOX. In aqueous solution, the amphiphilic PEG- b -DOX is able to self-assemble to form stable nanoparticles with a DOX loading content of approximately 40 wt% and a diameter of ∼143 nm. The resulting nanoparticles can simultaneously serve as an anticancer drug conjugate and as a drug carrier system. Here, the hydrophilic VRP could be encapsulated into the nano-carriers via a conventional dialysis method. The loading efficiency in mPEG- b -DOX nano-carrier was determined to be 53.97% and the loading content was found to be 7.71 wt%. The VRP-loaded nano-carriers grew slightly in size, to a diameter of ∼177 nm. We found that the release of DOX and VRP was much faster at a lower pH value. The biological activity of the nano-carriers were evaluated in vitro and compared with the DOX-loaded system. In doing so we found that the VRP-loaded nano-carrier features a much higher antitumor activity. Furthermore, the combined-system exhibits a significantly enhanced cytotoxicity with an elevated apoptosis rate observed for MCF-7/ADR used as a cell line in this in vitro study. This combinatory system and promising candidate for applications involving DOX chemotherapy proved to be easy to prepare and could be characterized in terms of biocompatibility, biodegradability, loading capacity, pH responsiveness and reversal of drug resistance. [ABSTRACT FROM AUTHOR]