Metilén kékkel impregnált szilika nanokonténerek hatása a kitozán vékony rétegre: Influence of methylene blue impregnated silica nanocontainers on the properties of chitosan thin layers

Chitosan is a biopolymer, which is synthesized by the deacetylation of chitin extracted from the shells of crustaceans [1]. It has drawn significant attention in the past few years in physical and electrochemical research, due to its eco-friendly nature, cost-efficient production process and the abundance of  its precursor. This study focuses on the characterization of methylene blue impregnated silica nanocontainers-chitosan systems. Glass and zinc were used as substrates. Methylene blue shows a high affinity toward silica nanocontainers [2] and its also a good model substance due to its intense color. It has been widely studied as a possible corrosion inhibitor [3]. Optical studies show that methylene blue accumulates significantly in the nanocontainers. The methylene blue can’t be impregnated directly in the chitosan thin coating, it can be introduced only through the nanocontainers. We have succeeded in producing stable methylene blue-nanocontainers/chitosan systems. Further research is needed to determine the electrochemical properties of these coatings and to optimize their anticorrosive effect. Kivonat A kitozán egy biopolimer melyet a rákfélék páncéljából kivont kitin deacilezésével állítanak elő [1]. Környezetbarát, gazdaságos, nyersanyaga könnyen hozzáférhető és sokrétű tulajdonságainak köszönhetően az utóbbi években kiemelt figyelmet kapott különböző fizikai és elektrokémiai kutatásokban. Munkánk során metilénkékkel impregnált szilika nanokonténerek/kitozán rendszerek tulajdonságait vizsgáltuk üveg és cink hordozókon. A metilénkék nagy affinitást mutat a szilika nanokonténerekkel szemben [2], valamint megfelelő modell anyag intenzív színének köszönhetően. A szakirodalomban széleskörűen vizsgálták mint lehetséges korrózió inhibitort [3]. Az optikai vizsgálatokból kitűnik, hogy a metilénkék jelentősen akkumulálódik a nanokonténerekben. A kitozán rétegbe nem lehet a metilénkéket impregnálni, de a nanokonténerek segítségével bevihető. Sikeresen létrehoztunk stabil metilénkék-nanokonténer/kitozán rendszereket. További kutatások szükségesek annak érdekében, hogy vizsgáljuk a bevonatok elektrokémiai tulajdonságait, illetve optimizáljuk ezek korrózióvédő hatását. &nbsp

In vitro evaluation of the multidrug resistance reversing activity of novel imidazo[4,5-b]pyridine derivatives

BACKGROUND/AIM: Malignant diseases present a significant public health burden worldwide and their treatment is further complicated by the phenomenon of multidrug resistance. Derivatives of imidazopyridine exhibit several remarkable pharmacological activities and they could reverse the multidrug resistance of cancer cells due to overexpressing P-glycoprotein. MATERIALS AND METHODS: A series of novel imidazo[4,5-b]pyridine derivatives were synthesized and their biological activities were evaluated in vitro using parental (PAR) and multidrug resistant (MDR; ABCB1-overexpressing) mouse T-lymphoma cells. The cytotoxic activity and selectivity of the tested compounds were assessed by the thiazolyl blue tetrazolium bromide (MTT) assay, the ABCB1 modulating activity was measured by rhodamine 123 accumulation assay using flow cytometry. RESULTS: Six compounds (b, c, d, f, h and i) showed moderate-to-high cytotoxic activity on the tested cell lines, while derivative i presented with promising selectivity towards the MDR cell line. Derivatives a, d, f, g and i were proven to be effective modulators of the ABCB1 multidrug efflux pump, with two compounds showing efflux pump modulatory activity at 2 muM concentration. CONCLUSION: Based on our experimental results, compounds that showed potent activity are those with a short carbon side chain; a methoxy group on the benzene ring; a heterocyclic (triazole) side chain and the presence of an alkylated N-atom at position 4

A Review of the Mitigating Methods against the Energy Conversion Decrease in Solar Panels

Using solar panels is one of the cleanest ways to generate electricity ever created by mankind. The efficiency of rapidly expanding solar panels decreases during their lifetime for several reasons, such as photodegradation, hot spots, potentially induced degradation, etc. Dirt and debris accumulation on the surface of the solar panels can also significantly contribute to their performance degradation due to the diminishing of the solar radiation reaching their active surfaces. Numerous degradation mitigation methods are cited in the literature. This article briefly outlines these basic measures

A Review of the Mitigating Methods against the Energy Conversion Decrease in Solar Panels

Using solar panels is one of the cleanest ways to generate electricity ever created by mankind. The efficiency of rapidly expanding solar panels decreases during their lifetime for several reasons, such as photodegradation, hot spots, potentially induced degradation, etc. Dirt and debris accumulation on the surface of the solar panels can also significantly contribute to their performance degradation due to the diminishing of the solar radiation reaching their active surfaces. Numerous degradation mitigation methods are cited in the literature. This article briefly outlines these basic measures

Wetting and swelling behaviour of N-acetylated thin chitosan coatings in aqueous media

Chitosan nanocoatings (thickness range of 120–540 nm) were produced on glass, zinc and silicon substrates with dip-coating and spin coating techniques to study their pH-dependent wetting and swelling behaviour. The coatings were N-acetylated with the methanolic solution of acetic anhydride to increase the degree of acetylation from 36 % to 100 % (according to ATR-FTIR studies). The measured contact angles of Britton–Robinson (BR) buffer solutions (pH 6.0, 7.4 and 9.0) were lower on the acetylated surfaces (ca. 50°), than that of their native counterparts (ca. 70°) and does not depend on the pH. Contrary, contact angles on the native coating deteriorated 10°-15° with increasing the pH. In addition, for native coatings, the decrease of the contact angles over time also showed a pH dependence: at pH 9.0 the contact angle decreased by 7° in 10 min, while at pH 6.0 it decreased by 13° and at a much faster rate. The constraint swelling of the coatings in BR puffer solutions was studied in situ by scanning angle reflectometry. The swelling degree of the native coatings increased significantly with decreasing pH (from 250 % to 500 %) due to the increased number of protonated amino groups, while the swelling degree of acetylated coatings was ca. 160 % regardless of the pH. The barrier properties of the coatings were studied by electrochemical tests on zinc substrates. The analysis of polarization curves showed the more permeable character of the acetylated coatings despite the non-polar character of the bulk coating matrix. It can be concluded that in the case of native coatings, 49 % of the absorbed water is in bound form, which does not assist ion transport, while in the case of acetylated coatings, this value is only 33 %. © 202