Učinak magnetnih nanočestica i ionske tekućine na performanse elektrokemijskih senzora

Magnetic nanoparticles and ionic liquid (IL, 1-hexyl-3-methyl-imidazolium bromide) based on graphene oxide (GO) composite provide unique physical and chemical properties in electrochemical sensors performance. Magnetic nanoparticles can cover active sites that increase chemical reactions with easy separation. IL increases the scan rate of electron transfer between the modified electrode and solution because it includes conductive adhesion properties. Also, IL in the next steps of design carbon paste electrodes (CPE) increases the cohesion. The study aims are to study the effects of magnetic nanoparticles and IL on the electrochemical detection of dopamine (DA). DA has a vital role in the mammalian central nervous system and change its value from the standard range leads broad mental diseases. But magnetic graphene oxide (MGO) may not exist capable of enhancing electrochemical signs alone. In this regard, after the synthesis of MGO, IL was established on composite. Then gold nanoparticles (AuNPs) and molecularly imprinted polymer (MIP) were modified MGO nanocomposite. MIP polymerization was continued by methacrylic acid (MAA) in the presence of DA as a template molecule. The developed sensor with modified nanocomposite studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified sensor based on nanocomposite with a broad concentration linear range, between 1×10-7 to 1×10-4 M and a limit of detection of 1×10-8 M (S/N=3) was used for the detection of DA in biological samples. Furthermore, these results prove that MGO was improved active sites of surface nanocomposite and IL was increased conductivity in the based electrochemical sensor for DA detection.Magnetne nanočestice i ionska tekućina (IL, 1-heksil-3-metil-imidazolijev bromid) na bazi kompozita grafenova oksida (GO) pružaju jedinstvena fizička i kemijska svojstva u izvedbi elektrokemijskih senzora. Magnetne nanočestice mogu pokriti aktivna mjesta koja povećavaju kemijske reakcije uz jednostavno odvajanje. IL povećava brzinu prijenosa elektrona između modificirane elektrode i otopine jer uključuje svojstva vodljive adhezije. Također, IL u sljedećim koracima dizajna elektroda ugljične paste (CPE) povećava koheziju. Cilj je studije proučavanje učinaka magnetnih nanočestica i IL-a na elektrokemijsku detekciju dopamina (DA). DA ima vitalnu ulogu u središnjemu živčanom sustavu sisavaca i promjena njegove vrijednosti iz standardnoga raspona dovodi do širokoga raspona mentalnih bolesti. Ali magnetni grafenov oksid (MGO) ne može sam poboljšati elektrokemijske signale. S tim u vezi, nakon sinteze MGO-a, IL je uspostavljen na kompozitu. Zatim su nanočestice zlata (AuNP) i molekularno utisnuti polimer (MIP) modificirali MGO nanokompozit. MIP polimerizacija nastavljena je metakrilnom kiselinom (MAA) u prisutnosti dopamina kao modelne molekule. Razvijeni senzor s modificiranim nanokompozitom proučavan je tehnikama ciklične voltametrije (CV) i diferencijalne pulsne voltametrije (DPV). Modificirani senzor na bazi nanokompozita sa širokim linearnim rasponom koncentracije, između 1×10-7 do 1×10-4 mol L-1 i granicom detekcije od 1×10-8 mol L-1 (S/N = 3) korišten je za detekciju dopamina u biološkim uzorcima. Ovi rezultati dokazuju da je MGO poboljšao aktivna mjesta površinskoga nanokompozita, a IL je povećao vodljivost u baziranome elektrokemijskom senzoru za detekciju dopamina

NOVI ELEKTROKEMIJSKI SENZOR TEMELJEN NA METALNIM NANOČESTICAMA I MOLEKULARNO UTISNUTOM NANOKOMPOZITNOM POLIMERU S PRIMJENOM U BIOLOGIJI

Metal nanoparticles trapped in a biopolymer composite due to electrical conductivity properties improve electrochemical sensors with biomedical and environmental applications. The study aims are to design a novel molecularly imprinted polymer (MIP) composite based on magnetic graphene oxide (Fe3O4@GO) modified silica (SiO2) and gold nanoparticles (AuNPs) to electrochemical detect serotonin (5-hydroxytryptamine, 5-HT). A suitable amount of 5-HT is effective on motivational functions and the environment because it is a serotonergic neurotransmitter. But the desired nanocomposite may have a relatively low recognition, therefore must be in choosing the type of functional monomer be careful. In this regard, the design of the electrochemical sensor began by synthesis of Fe3O4@GO-SiO2@AuNPs nanocomposite. Then, MIP electropolymerization was carried out by using p-aminothiophenol (PATP)-functionalized Fe3O4@GO-SiO2@AuNPs nanocomposite in the presence of 5HT as a template molecule. Electrochemical polymerization of MIP nanocomposite was developed using cyclic voltammetry (CV) and the electrochemical properties of 5-HT were studied use differential pulse voltammetry (DPV) technology in the 5HT solution. After optimization of preparation and measurement conditions on the designed sensor, the 5HT concentration range is 0.1 μM to 10 μM linearly, and the detection limit was 1 × 10-5 μM (S / N = 3). The wide concentration range and low detection limit were presented metal nanoparticles functionalized MIP with appropriate functional monomer have a great effect on the performance of the sensor. Furthermore, PATP-functionalized metal nanoparticles increase the conductivity and recognition of the prepared MIP electrochemical sensor to the quantification of 5-HT in biological samples with high selectivity and recovery.Metalne nanočestice zadržane u biopolimernome kompozitu zbog električne vodljivosti poboljšavaju svojstva elektrokemijskih senzora u biomedicini i izučavanju okoliša. Ovdje je prikazan novi molekularni utisnuti kompozitni polimer temeljen na grafenskom oksidu (Fe3O4→GO), modificiranome silicijevim dioksidom (SiO2) i nanočesticama zlata (AuNPs), a s ciljem elektrokemijskoga opažanja serotonina (5-hidroksitriptamin, 5-HT). Određeni iznos 5-HT-a utječe na motivaciju i doživljaj okoliša jer se radi o neurotransmiteru središnjega živčanog sustava. Kod odabira nanokompozita, a zbog učinkovitosti, funkcionalni monomer mora biti pažljivo odabran. Stoga je molekularno utisnuti polimer (MUP) generiran uporabom p-aminotiofenola (PATP), funkcionalnoga nanokompozita Fe3O4→GO-SiO2→AuNPs, u nazočnosti 5HT-a kao templatne molekule. Elektrokemijska polimerizacija nanokompozitnoga MIP-a načinjena je uporabom cikličke voltametrije (CV). Elektrokemijska svojstva 5-HT-a izučena su uporabom različitih tehnologija pulsne voltametrije (PV) u njegovoj otopini. Nakon optimizacije mjernih uvjeta i senzora, koncentracija 5-HT-a linearno je mijenjana u rasponu 0,1 – 10 μM, uz granicu opažanja 1 × 10-5 μM (S / N = 3). Širok raspon koncentracije i nizak prag opažanja te korištene metalne nanočestice MUP-a uz odabrani monomer imali su velik utjecaj na svojstva senzora. Nadalje, metalne čestice funkcionalizirane PATP-om povećale su vodljivost i mogućnost opažanja elektrokemijskih senzora na MIP te kvantificiranje sadržaja 5-HT-a u biološkim uzorcima s velikom točnošću

Application of a new nanoporous sorbent for extraction and pre-concentration of lead and copper ions

<p>The authors describe a method for the trace determination of copper (II) and lead (II) in water and fish samples using solid-phase extraction via siliceous mesocellular foam functionalised by dithizone. Siliceous mesocellular was functionalised with dithizone, and the resulting sorbent was characterised by scanning electron microscopy, surface area analysis, thermogravimetric/differential thermal analysis and FTIR. Following solid-phase extraction of target ions by the sorbent, copper and lead ions were quantified by flame atomic absorption spectrometry. Factors affecting the sorption and desorption of target ions by the sorbent were evaluated and optimised. The calibration plot is linear in the 1 – 500 μg L⁻¹ copper (II) and 3–700 μg L⁻¹ lead (II) concentration range. The relative recovery efficiency in real sample analysis is in the range from 96 to 102%, and precision varies between 1.7 and 2.8%. It is should be noted that the limits of detection for the copper and lead analysis were 0.8 and 1.6 μg L⁻¹, respectively. Also, the adsorption capacities for copper and lead ions were 120 and 160 mg g⁻¹, respectively. The obtained pre-concentration factor for the lead and copper ions by the proposed solid-phase extraction was 75. The method was successfully applied to the determination of low levels of copper (II) and lead (II) in tap, Caspian sea, Persian gulf and lake water and also their detection in fish samples.</p