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This paper describes an inquiry-based integrated laboratory project for green synthesis, characterization, and applications of silver and gold nanoparticles. In this project, students were able to ...

This work reports on the ability of Clitoria ternatea aqueous flower extract to prepare biogenic silver nanoparticles (AgNPs). The obtained AgNPs were used as efficient nanocatalysts for the elimin...

A simple reverse flow injection spectrophotometric determination of copper(II) was developed. The sensitivity enhancement of the reaction between copper(II) and pyrogallol red by cetyltrimethylammo...

This work demonstrates the capability of biosynthesized silver nanoparticles as a simple platform for copper(II) sensing together with the assessment of their antimicrobial activity. Butterfly pea aqueous extract was used to produce spherical AgNPs with sizes ranging from 10 to 30 nm showing the surface plasmon peak at 420 nm as a characteristic. The sensing capability of copper(II) was examined by observing an abrupt color change in colloidal AgNPs from a yellowish-brown to a light-violet color that was visible to the naked eye and occurred without any prior surface alteration. The synthesized AgNPs were found to be highly selective and sensitive in their application for identifying copper(II), with a detection limit of 6 mg L−1. The overall expression of copper(II) content in water and pharmaceutical samples was consistent with results obtained using the conventional AAS method. Furthermore, the antibacterial activity of the obtained AgNPs was also determined by the broth microdilution method. The minimum inhibitory concentration and minimum bactericidal concentration values against Methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, Acinetobacter baumannii clinical, and Acinetobacter baumannii were 0.16, 0.16, 0.32, 0.64 and 5.10, 5.10, 1.27, 1.27 μg mL−1, respectively.

A laboratory experiment utilizing locally available Indian Gooseberry (Phyllanthus emblica Linn.) extract as a bioreagent to determine iron(III) is described with the goal of providing students with hands-on experience in spectrophotometry and green chemistry. Spectrophotometry was used to measure the concentration of the complex formed between iron(III) and gallic acid, an active compound found in Indian Gooseberry extract. Excellent results from the quantitative analysis of iron(III) in water were achieved. In this case, the bioreagent was used to replace the conventional hazardous chemicals that are usually employed as chromogenic reagents. The use of Indian Gooseberry extract is simple, inexpensive, and environmentally friendly. This experiment is appropriate for use as a simple spectrophotometric protocol for undergraduate teaching in an analytical- or general-chemistry laboratory.

This work presents a green synthesis of silver nanoparticles (AgNPs) using Citrullus lanatus juice extract. The biologically synthesized AgNPs and functionalized AgNPs using L-cysteine (Cys-AgNPs) were characterized by the UV-Vis spectroscopy, the FT-IR spectroscopy, and the scanning electron microscopy (SEM) analysis. The surface-plasmon resonance (SPR) bands of the AgNPs and Cys-AgNPs and appears at 420 and 415 nm, respectively. The SEM image revealed that the particles had a spherical shape and size distribution of 20–40 nm. Application of Cys-AgNPs in terms of heavy metal selectivity showed that it exhibited selectivity against nickel(II) which was confirmed by the color change from yellow to orange and the appearance of a new SPR band at 455 nm. The predicted structures of AgNPs and Cys-AgNPs showed that the complexes were formed through the electrostatic interactions and the shift of the SPR band from theoretical calculations are in accordance with experiment. Accordingly, this eco-friendly approach showed the successful application of the biologically green synthesized AgNPs modified by the L-cysteine addition for colorimetric detection of nickel(II). This proposed method could be considered as an efficient probe for the colorimetric sensing of nickel(II) with simplicity, rapidity, low cost and environmental reservation.

A green, simple, and rapid synthesis of gold nanoparticles using plant extract, Cryptolepis buchanani Roem. and Schult, and their applications are first described in this paper. The formation of gold nanoparticles was visually observed by the appearance of a ruby red color, which was further indicated by an absorption peak at 530 nm in UV-Vis spectroscopy. Optimization of reaction parameters for the gold nanoparticles was also investigated. Various analytical techniques were employed as part of the process of characterizing the resulting gold nanoparticles. Fourier transform infrared (FTIR) analysis revealed that the phenol compounds present in the extract were responsible for gold(III) reduction and stabilization of gold nanoparticles. Transmission electron microscopy (TEM) analysis showed that the gold nanoparticles were spherical in shape with an average diameter of 11 nm. Powder X-ray diffraction (XRD) pattern indicated that the green synthesis approach produced highly crystalline, face-centered cubic gold nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of elemental gold in the prepared nanoparticles. The negative zeta potential value of gold nanoparticles was found to be -30.28 mV. The green synthesized gold nanoparticles expressed effective antibacterial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Acinetobacter baumannii and exhibited an excellent catalytic property in terms of its reduction ability of methylene blue.

A sequential injection analysis (SIA) spectrophotometric method for the determination of trace amount of mercury (II) with pyrogallol red (PGR) was described. The method was based on the measurement of absorbance of the mercury (II)–PGR complex, yielding a light yellow-coloured product at pH 9.0 with absorption maximum at 370 nm. The SIA parameters affecting the signal response were optimised in order to obtain the better sensitivity and minimum reagent consumption. The linear range for determination of mercury (II) was over the range of 0.1–2.0 mg L−1. The limit of detection and limit of quantification, calculated following IUPAC were 0.06 and 0.10 mg L−1, respectively. The repeatability was 1.25% (n = 10) for 0.5 mg L−1 of mercury (II). The proposed method was successfully applied to determine the mercury (II) in commercial cosmetics, local Thai traditional medicines and water samples with a sampling rate of 40 h−1. Results obtained were in justifiable agreement with those obtained by the offici...

Modification of a minicomputer numerical controller with a low cost diode laser for fabrication of polymethyl methacrylate chips has been demonstrated. The maximum power of the diode laser was 5 W at 808 nm. The scanning speed was 1.0–10.0 mm s−1 by the movement of x and y stages. The patterns of microchannels on the chip were designed using drawing software and then applied to software that controlled the operation of the controller. The parameters that affected the channel depth, width, and smoothness were studied by varying the laser power and speed of polymethyl methacrylate sheets with surface area of 4.0 × 6.0 cm2 and thickness of 0.1 cm. The optimum conditions were used to fabricate microchannels on each sheet giving different depths and widths over the range of 74 µm to 554 µm and 147 µm to 393 µm, respectively. The most appropriate conditions for polymethyl methacrylate chip fabrication were 5 W and 3 mm s−1 for the laser diode power and the speed, respectively. The optimal dimensions of the micr...

The use of natural reagents from plant extracts for chemical analysis is one approach in the development of green analytical chemistry methodology. In this work, a natural reagent extracted from Phyllanthus emblica Linn. has been applied for the determination of iron(III) using a simple flow injection spectrophotometric method. The method was based on the measurement of a dark-purple complex formed by the reaction between iron(III) and the extracted solution in an acetate buffer (pH 5.6) at 570 nm. Under the optimum conditions, a linear calibration graph in the range of 0.50–20.0 mg L−1 iron(III) was obtained with a correlation coefficient (r2) of 0.9996. The limit of detection and limit of quantification were 0.31 and 0.50 mg L−1, respectively. The relative standard deviation was less than 2.50%. The proposed method was successfully applied for quantitative analysis of iron(III) in pharmaceutical preparations and water samples with a sampling rate of 90 samples h−1. The results are in good agreement with those obtained by the official ICP-OES technique at the 95% confidence level. The presented method provides a simple, cost-effective and environmentally friendly approach which is suitable and useful for determining iron(III). Therefore, it can be considered as an alternative analytical technique in green chemistry.

A spectrophotometric microfluidic bioreactor system is described for the determination of organophosphorus pesticides. The glass chip was designed and fabricated for in situ monolithic preparation and subsequently acetlycholineserase (AChE) immobilization via a covalent bonding method. The porous polymer monolith was prepared using glycidyl methacrylate, ethylenedimethacrylate and 2,2-dimethoxy-1,2-diphenylethan-1-one in binary porogenic solvents of cyclohexanol and dodecanol. The epoxide groups of monolith were reacted with ethylenediamine and gluteraldehyde to allow immobilization of the enzyme using their amine groups. Organophosphorus pesticides can be determined by measuring their inhibition effect on the enzyme AChE using Ellman's reaction. A linear relationship between the absorbance and percentage inhibitions was obtained over the concentration range of 0.25 to 2.50 mg L−1 paraoxon with a correlation coefficient (r 2) of 0.9974. The limit of detection (LOD) defined as 10% inhibition (I 10) was 0.1...

A monolith based immobilized acetylcholinesterase (AChE) flow-through reactor has been developed for the determination of copper(II) using flow injection spectrophotometric system. The bioreactor was prepared inside a microcapillary column by in situ polymerization of butyl methacrylate, ethylene dimethacrylate, and 2,2-dimethoxy-1,2-diphynyletane-1-one in the presence of 1-decanol, followed by vinyl azlactone functionalization and AChE immobilization. The behavior of AChE before and after being immobilized on the monolith was evaluated by kinetic parameters from Lineweaver and Burk equation. The detection was based on measuring inhibition effect on the enzymatic activity of AChE by copper(II) using Ellman’s reaction with spectrophotometric detection at 410 nm. The linear range of the calibration graph was obtained over the range of 0.02–3.00 mg L −1. The detection limit, defined as 10% inhibition ( I10), was found to be 0.04 mg L −1. The repeatability was 3.35 % ( ) for 1.00 mg L −1 of copper(II). The proposed method was applied to the determination of copper(II) in natural water samples with sampling rate of 4 h −1.

A novel extrusion printing system was used to create drug delivery structures wherein dexamethasone-21-phosphate disodium salt (Dex21P) was encapsulated within a biodegradable polymer (PLGA) and water soluble poly(vinyl alcohol) (PVA) configurations. The ability to control the drug release profile through the spatial distribution of drug within the printed 3-dimensional structures is demonstrated. The fabricated configurations were characterised by optical microscopy and SEM to evaluate surface morphology. The results clearly demonstrate the successful encapsulation of dexamethasone within a laminated PLGA:PVA structure. The resulting drug release profiles from the structures show a two stage release profile with distinctly different release rates and minimal initial burst release observed. Dexamethasone release was monitored over a 4-month period. This approach clearly demonstrates that the extrusion printing technique provides a facile and versatile approach to fabrication of novel drug delivery platforms.