One-pot synthesis of hydrophilic and hydrophobic fluorescent carbon dots using deep eutectic solvents as designer reaction media

Dogan Calhan, Selda | Alas, Melis Ozge | Asik, Muge | Genc, Rukan

Carbon dots are often synthesized in the presence of a carbon source and passivating agents in which they are crucial for an enhanced fluorescence. The solvent choice and/or combination to be used in the synthesis of these nanoparticles can influence their surface chemical composition, morphology, and fluorescence properties. In this study, highly fluorescent carbon dots were synthesized using deep eutectic solvents of different compositions as green solvent media and doping agent. Resulting carbon dots were then separated by their hydrophilicity/hydrophobicity using a three-phase solvent system (water/ acetone/chloroform) and compared with traditional centrifugation-based separation method. Carbon dots with a size below 20 nm and quantum yield reaching 50% were obtained. Many properties of them including surface functional groups, optical, fluorescence, and electric properties were shown to be determined by the deep eutectic solvent composition.

Synthesis, crystal structure, thermal decomposition, and XPS studies of homo and heterotrinuclear Cu(II)–Cu(II)–Cu(II) and Cu(II)–Ni(II)–Cu(II) complexes obtained from salpn type ligands

In this study, a mononuclear CuL complex was prepared by the use of bis-N,N′-(salicylidene)-1, 3-propanediamine (LH2) and Cu2+ ion. NiCl2 and NiBr2 salt were treated with this complex in dioxanewater medium and two new complexes [(CuL)2NiCl2(H2O)2] and [(CuL)2NiBr2(H2O)2)] with Cu(II)–Ni(II)–Cu(II) nucleus structure were obtained. In addition to this bis-N,N′-(2-hydroxybenzyl)-1,3-diaminopropane (LHH2) was prepared by the reduction of LH2 with NaBH4 in MeOH medium. The treatment of this reduced complex with Cu2+ ion resulted a complex [(CuLH)2CuCl2] with a structure of Cu(II)–Cu(II)–Cu(II). The complexes prepared were characterized by the use of elemental analysis, IR spectroscopy, thermogravimetric and X-ray diffraction methods. The crystal structures of [(CuL)2NiBr2(H2O)2] (СIF file CCDC 1448402) and [(CuLH)2CuCl2] (СIF file CCDC 1448401) complexes were elucidated. It was found that halogen ions are coordinated to terminal Cu2+ ions which are in a distorted square pyramid coordination sphere. It was determined that the central Cu(II), which joins terminal square pyramidal Cu(II), was coordinated only by the phenolic oxygens of the ligand while the central Ni(II) was coordinated by two phenolic oxygens of the organic ligand and two water molecules. These complexes were investiga...

Applications of carbon nanotubes for determination of inorganic and organic species in biological and clinical samples

Doğan, Selda

Development of new adsorbent materials for solid phase extraction for preconcentration of inorganic and organic species is one of the important topics for analytical chemistry. Carbon nanotubes can be promising for preconcentration study as an adosrbent material since their discovery in 1991 because of their unique chemical and physical properties. In recent years, carbon nanotubes are succesfully used for preconcentration of both inorganic and organic compounds from various matrix with solid phase extraction. This review was focused on several applications for determination of inorganic and organic species and some drugs in biological and clinical samples by using solid phase extraction methods with carbon nanotubes. In this context, properties of carbon nanotubes and their functionalization and usage of solid-phase extraction adsorbent are discussed. In addition, some studies from the literature are presented in tables.

Enrichment of copper and nickel with solid phase extraction using multiwalled carbon nanotubes modified with Schiff bases

Dogan Calhan, Selda

The behaviour of some Schiff bases in the presence of metal ions is very selective in complex formation. In this study, new, selective and easily prepared adsorbent materials have been developed. Multiwalled carbon nanotubes (MWCNTs) are quite suitable as supporting material for preparation of new solid phase adsorbents modified with Schiff bases due to their selective nature. Different Schiff bases were designed and synthesised as adsorbent agents for Ni(II) and Cu(II) ions, according to the literature, and MWCNTs were modified with these Schiff bases. The modification of CNTs was performed by adsorption from the alcoholic solution of Schiff base. The measurements of Ni(II) and Cu(II) ions were carried out using ICP-MS. Different parameters such as pH, model and eluent solution flow rates, eluent type, amount of ligand, sample volume and effect of foreign ions, which have an effect upon recovery of analytes, were investigated. The obtained results indicated that enrichment can be done with six modified adsorbent materials for Cu(II) at pH 9 and two modified adsorbent materials for Ni(II) at pH 8. It was concluded that four adsorbent materials were selective only for the enrichment of Cu(II). Merely one modified adsorbent material was noneligible for the enrichment of Cu(II) and ...

Biyolojik örneklerde elektrotermal atomik absorpsiyon spektroskopisi ile kurşun tayininde nitrik asitin ve bazı ortam düzenleyicilerin etkisinin incelenmesi

Dogan, Selda | Duman, Ramazan

Bu çalışmada, elektrotermal atomik absorpsiyon spektroskopisi (ETAAS) ile biyolojik örneklerde kurşun tayininde nitrik asit ve bazı ortam düzenleyicilerin etkileri incelendi. Farklı nitrik asit derişimleri kullanılarak Pt + Pd, Pd + Mg(NO3)2 ve NH4H2PO4 + Mg(NO3)2 ortamlarında piroliz ve atomlaşma sıcaklığı optimizasyon çalışmaları yapıldı. % 10 HNO3 + NH4H2PO4 + Mg(NO3)2 ortamı en uygun ortam olarak belirlendi. Yöntemin doğruluğu CRM BCR-397 insan saçı, NIST 2976 midye dokusu ve HIGH EP-H-1 içme suyu standart referans maddeleri ile kontrol edildi. Ölçülen değerlerin, sertifika değerlerinden sapmasını göstermek için bağıl hata hesaplandı ve belirlenen ortamda üç standart referans madde için bağıl hata % 10'un altında bulundu. Belirlenen koşullarda kurşunun gözlenebilme sınırı (LOD) 0,67 μg/L, tayin sınırı (LOQ) 2,01 μg/L olarak hesaplandı. In this study, determination of lead in biological materials by electrothermal atomic absorption spectroscopy was investigated. Pyrolysis and atomization temperatures were optimized in Pt + Pd, Pd + Mg(NO3)2 and NH4H2PO4 + Mg(NO3)2 mixtures using various nitric acid concentrations. % 10 HNO3 + NH4H2PO4 + Mg(NO3)2 mixtures was designated as the best conditions. The accuracy of the method was tested by certificated reference standard m...

Determination of zinc and lead in human hair by atomic absorption spectrometry after digestion with tetramethylammonium hydroxide and conventional methods

Dogan, Selda

Various digestion methods were compared for determination of zinc and lead in human hair by atomic absorption spectroscopy. For the digestion of hair samples, alkaline digestion in tetramethylammonium hydroxide was used in addition to conventional acidic digestion methods like dry ashing, wet ashing and microwave digestion in acid. The accuracy of the methods was tested by certified standard reference material, CRM BCR-397 human hair. According to the statistical evaluation of the results, there are no significant differences between the four digestion methods. Relative errors of the certified value of CRM BCR-397 were less than 10% except for the tetramethyl-ammonium hydroxide digestion method.

Two non-linear azide containing heteronuclear complexes: crystal structure and thermal decomposition

Bis-N,N'(salicylidene)-2,2'-dimethyl-1,3-propanediamine (LDMH2) has a high tendency to form polynuclear complexes. Two trinuclear complexes were obtained using this ligand and azide ions; (CuLDM)(2) center dot A Mn(N-3)(2) center dot A (DMF)(2), [(C19H20N2O2Cu)(2) center dot A Mn(N-3)(2) center dot A (C3H7NO)(2)] and (CuLDM)(2) center dot A Cd(N-3)(2) center dot A (DMF)(2), [(C19H20N2O2Cu)(2) center dot A Cd(N-3)(2) center dot A (C3H7NO)(2)]. The structures were identified with X-ray methods. TG and DSC methods were also employed to these complexes. Studies showed the (CuLDM)(2) center dot A Mn(N-3)(2) center dot A (DMF)(2) and (CuLDM)(2) center dot A Cd(N-3)(2) center dot A (DMF)(2) to be non-linear. Also mu-bridges were not encountered for the azide ions but were seen to form between the Cu and other metal via phenolic oxygens. Thermal analysis showed exothermic degradation of the azide ions destroying the trinuclear structure. Although azide containing structures show explosive characteristics, this was not observed for the present compounds.

Nickel(II) complexes prepared from NNN type ligands and pseudohalogens : Synthesis, structure and thermal decomposition

Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N3)2]·MeOH (I) and thiocyanate [Nidmpp(SCN)2·MeOH] (VI) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen to be dinuclear as stated in literature, space group P21/n, monoclinic, a=10.503, b=10.681, c=13.291 Å, β=106.56° and Z=2 whereas complex VI was found to be mononuclear, space group P21/n, monoclinic, a=8.646, b=12.614, c=20.697 Å, β=97.18° and Z=2. The Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing complexes, followed by irregular degradation above 300°C.

Comparison of hydride generation atomic absorption and electrothermal atomic absorption techniques for determination of lead in blood

In this study, hydride generation atomic absorption and Zeeman background corrected electrothermal atomic absorption techniques was compared for determination of lead in blood. Blood samples were digested by microwave acid digestion and then Pb(IV) formation was realized by using (NH4)(2)Cr2O7 in 0.72 mol/l HNO3. To increase the stability of Pb(IV) different chelating agents were added. Malic acid was a more suitable chelating agent than lactic, tartaric and salicylic acids. After PbH4 was formed, NaBH4 was swept with argon into the heated quartz tube for atomization. (NH4)(2)Cr2O7 + HNO3 + malic acid medium was chosen as the most suitable medium. After these conditions were fulfilled, Pb levels of the samples were measured first by hydride generation atomic absorption and then by Zeeman background corrected electrothermal atomic absorption techniques. Statistical factors of the Pb levels from 78 persons were evaluated and consequently it was decided that HGAAS could well be an alternative to the ETAAS method which is known as the most reliable.

Two new mononuclear Ni(II) complexes with reduced ONNO type Schiff base

N, N′-bis (salicylidene)-1, 3-propanediamine (LH 2) and N, N′-bis (salicylidene)-2, 2′-dimethyl-1, 3-propanediamine (DMLH 2) were reduced to phenolic amines by using NaBH 4. Mononuclear complexes were obtained with Ni (II) in a N 3 O 6 coordination sphere with these amines and N 3–ions, in DMF media. It was established with the XRD studies that the coordination spheres were distorted octahedral and the complex obtained with LH 2 formed dimeric structures via phenolic OH bonds. The other complex was seen to have monomeric structure. The complexes were characterized by X-ray diffraction, elemental analysis, termogravimetry, IR spectroscopy and simple magnetic susceptibility (Gouy method). In addition, cyclic voltammetric studies have been performed.

Relationships Between Tensile Strength, Ascorbic Acid, Hydroxyproline, and Zinc Levels of Rabbit Full-Thickness Incision Wound Healing

Purpose This work was carried out to follow up the healing of full-thickness incision wounds opened on the back skin of rabbits in order to gain insight into the periodical correlation among such factors as ascorbic acid, collagen (hydroxyproline), the zinc content, and tensile strength of wound tissue. The need to provide vitamin C or zinc supplements after such wound incisions is also discussed. Methods Full-thickness incision wounds and the ascorbic acid and hydroxyproline levels were measured in 24 rabbits by spectrophotometric methods on day 0 and on the 3rd, 5th, 7th, and 15th days after operation. The tensile strength was measured by a polygraph using a force displacement transducer. The zinc levels of the wounds were measured by atomic absorption spectrophotometry. Results The zinc and hydroxyproline levels reached the peak levels on the 5th day, but the tensile strength of wound increased sharply on the 7th day after wounding while the zinc levels did not change. These results indicated that in the first 7 days of wound healing, high levels of ascorbic acid, hydroxyproline, and zinc cumulation occurred in the wound tissue, and the tensile strength reached its highest level on the 15th day without any supplementation. Conclusion The supplementation of zinc ...

Serum zinc and alkaline phosphatase values in pediatric bone marrow transplantation patients

Zinc (Zn) plays an important role in the maintenance of immune functions, including cellular/humoral immunity, and in the prevention of oxidative injury. Therefore, the maintenance of a normal Zn status may be important in bone marrow transplantation (BMT) patients. Serum Zn levels were determined in 35 children during the BMT period. In addition, as Zn-related factors, serum Cu levels and alkaline phosphatase (AP) activity were also measured. There was a significant decrease in Zn and AP values during the immediate post-transplant period (lowest at day +7) when compared to pre-BMT levels (p < .01). The patients who developed hypozincemia were more likely to be transplanted for a diagnosis of malignant disorder and were younger, and adverse events appeared to occur more frequently. This preliminary study suggests that maintaining a normal Zn status may be important in BMT patients and that Zn deficiency may be a risk factor for adverse events.

KOKU ALMA BOZUKLUKLARINDA PLAZMA, ERİTROSİT VE SAÇ ÇİNKO DÜZEYLERİ

Koku alma bozukluklarına sık rastlanılmakta ancak nedense pek önem verilmemektedir. Çinko eser elementide yerkabuğunun temel maddelerinden biri olduğu gibi canlıların birçok enzim sisteminde rol oynamaktadır: Bizde çalışmamızda 25 hiposmik olguda Koku alma bozukluğu ile Çinko elementi arasındaki ilişkiyi araştırdık. Ayrıntılı anamnez ve ardından Olfaktometrik ölçümleri yapıldı. Çinko düzeyleri için kan ve saç örnekleri alındı. Hastalarda koku alma eşiği, koku alma bozukluğu süresi, derecesi, sigara içme süresi ve miktarı ile plazma, eritrosit ve saç Çinko değerleri karşılaştırıldı. Çalışmada hiposmik olguların Çinko değerleri plazma 71.6 ug/dl, eritrosit 10.83 ug/ml ve saç 179.9 ppm olarak bulunmuş ve hepsi de kontrol grubu değerlerinden anlamlı düşüktür. Sonuçta Çinko eksikliğinin idiopatik olarak adlandırılan koku alma bozukluklarına yol açabileceğini düşünüyoruz. Ayrıca sigara içmenin, içilen sigara miktarının, hiposmi süresinin de olumsuz yönde etki yapacağını belirtiyoruz. Saç ve plazma Çinko değerlerinin koku alma bozukluğunu takip için uygun yöntemler olduğunu savunuyor, eksojen Çinko verilmesinin de tedavi edici olabileceğine inanıyoruz. Olfactive disorders are frequent, nevertheless they are yet to gain importance in clinical practice. Zinc is an essential element which ...

Denizli İlinde Okul Öncesi Çocuklarda Saç Çinko Düzeyleri Ve Gelişme

Bu çalışmada, Denizli Çocuk Bakım Evi’nden 2-6 yaşlar arasında 24 çocukta boy, ağırlık, bazı hematolojik parametreler ve saç çinko ölçümleri yapılmıştır. 2-6 yaş grubunda boyu 10’cu persentilin altındaki çocukların oranı çok yüksektir (%62.5). Aynı şartlarda yaşayan 7-10 yaş grubunda ise oran %33.3 bulunmuştur. Boy gelişmesi 10’cu persentilin altında olanların saç çinko düzeyleri ile gelişmesi normal olanlar arasında istatistik açıdan anlamlı bir fark bulunmamıştır. Okul öncesi dönemde diyet özelliği nedeniyle her ne kadar saç çinko düzeyleri normal bulunsa da marjinal çinko eksikliği gelişme geriliği nedenlerinden biri olabilir. Kesin kanıt bu çocuklara çinko suplemantasyonu yapıldıktan sonra gelişmesinin izlenmesi ile konabilir.