Tissue-specific accumulation, transformation, and depuration of fipronil in adult crucian carp (Carassius auratus).

Accumulation and biotransformation of pesticides in fish tissues are essential to assess their toxicity and associated human exposure risk. The mechanisms on time-dependent and tissue-specific accumulation and transformation of fipronil in adult fish are limited. An experiment consisting of 25-d uptake of fipronil at two levels (10 and 50 µg/L) and 25-d depuration in adult crucian carp (Carassius auratus) was conducted. Fipronil concentration at 25-d exposure was tissue-specific with the order of liver > kidney > blood > muscle. The uptake rate constant of fipronil in the liver (low exposure group: 2.38 ± 0.27 L/kg/d; high exposure group: 1.10 ± 0.11 L/kg/d) was significantly higher than that in other tissues (p < 0.05), and the lowest in muscle (low exposure group: 0.10 ± 0.01 L/kg/d; high exposure group: 0.16 ± 0.11 L/kg/d). The bioconcentration factors of fipronil in different tissues were 1.04-12.7 L/kg wet weight and 177-4268 L/kg lipid. The tissue-blood distribution coefficients of the liver and kidney were lower than 1 based on lipid normalized concentration but higher than 1 based on wet weight concentration, suggesting fipronil was dispersed into other tissues mainly via blood in the lipid-combination pattern. Fipronil sulfone had 1.2-32 times higher concentration and longer depuration time than fipronil, implying fipronil sulfone was more retender in fish bodies. The estimated daily intake of fipronil via fish muscle consumption at 25-d exposure was 8.5-101 and 27-320 ng/kg bw/d for adults and children, respectively. Overall, the human health risk of fipronil and its metabolites with consumption of the polluted fish cannot be negligible.

Mussel Adhesive Mimetic Silk Sericin Prepared by Enzymatic Oxidation for the Construction of Antibacterial Coatings.

With the rapid development and advancement in orthodontic and orthopedic technologies, the demand for biomedical-grade titanium (Ti) alloys is growing. The Ti-based implants are susceptible to bacterial infections, leading to poor healing and osteointegration, resulting in implant failure or repeated surgical intervention. Silk sericin (SS) is hydrophilic, biocompatible, and biodegradable and could induce a low immunological response in vivo. As a result, it would be intriguing to investigate the use of hydrophilic SS in surface modification. In this work, the tyrosine moiety in SS was oxidized by tyrosinase (or polyphenol oxidase) to the 3,4-dihydroxyphenylalanine (DOPA) form, generating the catechol moiety-containing SS (SSC). Inspired by the adhesion of mussel foot proteins, the SSC coatings could be directly deposited onto multiple surfaces in SS and tyrosinase mixed stock solutions to create active surfaces with catechol groups. Further, the SSC-coated Ti surfaces were hybridized with silver nanoparticles (Ag NPs) via in situ silver ion (Ag+) reduction. The antibacterial properties of the Ag NPs/SS-coated Ti surfaces are demonstrated, and they can prevent bacterial cell adhesion as well as early-stage biofilm formation. In addition, the developed Ag NPs/SSC-coated Ti surfaces exhibited a negligible level of cytotoxicity in L929 mouse fibroblast cells.

Simultaneous deposition of tannic acid and poly(ethylene glycol) to construct the antifouling polymeric coating on Titanium surface.

Titanium (Ti) and its alloys are primarily explored to produce biomedical implants owing to their improved mechanical stability, corrosion resistance, low density, and good biocompatibility. Despite, Ti substrate surfaces are easily contaminated by plasma proteins and bacteria. Herein, a simple one-step process for the simultaneous deposition of a polyphenol tannic acid (TA) and four-armed poly(ethylene glycol) (PEG10k-4-OH) on the Ti substrate (Ti-TA/PEG) surface was described. Additionally, a two-step process has been employed to fabricate the Ti-TA-PEG surface via successive deposition of TA and PEG10k-4-OH for comparison. The resultant Ti-TA/PEG surface prepared by simultaneous deposition of TA and PEG10k-4-OH exhibits higher coating thickness and better surface coverage than the Ti-TA-PEG surface. The Ti-TA/PEG and Ti-TA-PEG surfaces could actively inhibit the non-specific adsorption of proteins, suppress the bacterial and platelet adhesion, and prevents biofilm formation. Moreover, the Ti-TA/PEG surface displays a better antifouling performance than the Ti-TA-PEG surface. Thus, the present study demonstrates a simple and convenient approach for constructing polymeric coating with good anti-adhesive properties on the Ti substrate surface.

Intradermal administration of green synthesized nanosilver (NS) through film-coated PEGDA microneedles for potential antibacterial applications.

Skin infections caused by pathogens, including bacteria, fungi and viruses, are difficult to completely eliminate through standard topical administration, owing to the restricted drug permeation into the epidermis layer. Herein, we developed a poly(ethylene glycol) diacrylate (PEGDA) microneedle patch with surface coating of a nanosilver (NS) encapsulated gelatin/sucrose film for antibacterial applications, by virtue of enhanced skin permeation by microneedle penetration and efficient drug delivery through rapid film dissolving. NS was facilely synthesized through a green process based on the bioinspired crystallization of ionic state silver in the presence of a silk fibroin (SF) template. A gelatin/sucrose polymeric film encapsulating NS was dressed on the surface of the mold cavity, and film-coated PEGDA (PEGDA/film-NS) microneedles were subsequently fabricated through standard ultraviolet (UV) light-induced polymerization. To demonstrate their advantages for therapeutic applications, the physicochemical properties of the as-developed microneedles were characterized in terms of their morphology, composition, mechanical strength, etc. Moreover, rapid NS release from PEGDA@film-NS microneedles driven by the aqueous environment was demonstrated under physiological conditions. Additionally, such film-coated microneedles exhibited good mechanical strength for skin penetration, and their antibacterial activity against Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus) as well as Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was verified using bacterial suspension in vitro. Altogether, such a minimally invasive strategy exhibited good potential for realizing a broad-spectrum antibacterial effect, which may provide a practical methodology for the management of polymicrobial skin infection during clinical trials.

Amino-containing tannic acid derivative-mediated universal coatings for multifunctional surface modification.

The development of a universal coating strategy for the construction of functional surfaces and modulation of surface properties is of great research interest. Tannic acid (TA) could serve as a sole precursor for the deposition of colorless coatings on substrate surfaces. However, the deposition of TA requires a high salt concentration (0.6 M), which may limit its practical application. Herein, primary amine moieties were introduced on the gallic acid groups in TA. The resultant amine-containing TA derivative (TAA) can self-polymerize under mild conditions (10 mM, Tris buffer), and form uniform and colorless coatings in a material-independent manner. In comparison with the TA coating under the same preparation conditions, the TAA coating exhibits an increased thickness as measured by ellipsometry. The TAA coating is adapted for secondary surface functionalization. The hydrophilic mPEG brushes can be grafted on the TAA coating to inhibit non-specific protein adsorption. A biotin probe can be immobilized on the TAA coating to promote specific binding with avidin. In addition, the TAA coating can be utilized for in situ reduction of silver ions to AgNPs. The resulting AgNP-loaded TAA coating can inhibit bacterial adhesion and prevent biofilm formation.

Discovery of diverse diterpenoid scaffolds from Euphorbia antiquorum and their activity against RANKL-induced osteoclastogenesis.

Seven new diterpenoids, euphorantones A-D (1, 3, 6, and 10), 8,12,13-epi-3,7,12-O-triacetyl-8-O-(2-methylbutanoyl)-ingol (9), 8,12,13-epi-3,12-O-diacetyl-7-O-benzoyl-8-methoxyingol (11), 2,3-epi-7,12-diacetate-8-benzoate-ingol (12), together with eighteen known compounds (2, 4-5, 7-8, and 13-25), were isolated from the aerial parts of Euphorbia antiquorum L.. The structures of new compounds 1, 3, 6, and 9-12 were elucidated by extensive spectroscopic analyses. The absolute configurations of new compounds were assigned using X-ray diffraction, Rh2(OCOCF3)4-induced CD spectrum, and confirmed through comparison of the calculated and experimental 13C NMR and electronic circular dichroism (ECD) data. Compounds 1-25 were evaluated for their inhibition of RANKL-induced osteoclastogenesis. Compound 1 showed the most potent inhibition of RANKL-induced osteoclastogenesis with IC50 value of 0.3 µM. It inhibited NFAT transcript activity and osteoclast related genes TRAcP, CTSK, and NFATc1 expression.

Deposition of catechol-functionalized chitosan and silver nanoparticles on biomedical titanium surfaces for antibacterial application.

The titanium (Ti) and its alloys have been widely used for dental and orthopedic implants. However, the Ti-based implants may suffer from bacterial infection, which would result in insufficient healing, implant failure and repeated surgical intervention. It is of great interest to inhibit the bacterial adhesion and colonization on the Ti-based implants by introducing proper surface coatings. In this work, a simple method was employed to synthesize the water-soluble catechol-containing chitosan (CACS). The CACS coatings can be deposited onto various substrate surfaces and exhibit substrate-independent behavior. The CACS-coated Ti surfaces were further deposited with silver nanoparticles (Ag NPs) via in-situ reduction of Ag+ ions using catechol moieties as the reducing agents. The resulting AgNPs/CACS-coated Ti surfaces exhibit antibacterial properties and can prevent the surface adhesion of bacterial cells, as evidenced by the inhibition zone test, live/dead bacterial staining assay and spread plate method. In addition, they show negligible cytotoxicity to L929 mouse fibroblast cells.

Chemical constituents from Daphne tangutica and their cytotoxicity against nasopharyngeal carcinoma cells.

Two new sesquiterpenoids (1-2), together with 30 known compounds including one sesquiterpenoid (3), six diterpenoids (4-9), fourteen lignans (10-23), and nine other kinds of compounds (24-32), were isolated from the stems of Daphne tangutica Maxim. Their structures were determined through extensive spectroscopic analyses, and the absolute configuration of daphnoid A (1) and B (2) were determined by the experimental and calculated electron circular dichroism (ECD) spectra. All the isolates were evaluated against two human nasopharyngeal carcinoma cells (HONE-1 and SUNE-1). Compound 25 (daphnenone) showed potent cytotoxicity toward HONE-1 and SUNE-1with IC50 values of 2.23 and 1.43 µM, respectively. Further studies indicated that compound 25 exhibited cytotoxic effects by inducing tumor cell apoptosis and arresting the cell cycle at G2/M phases in HONE-1 cells.