Faridah Salam

Optimization of peak current of poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube using response surface methodology/central composite design

Modification of electrode surface with poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube (PEDOT/MWCNT) composite prepared by electrodeposition technique was reported in this study. The optimization of peak current response of PEDOT/MWCNT was performed by utilizing the combination of response surface methodology and central composite design (RSM/CCD). The effect of each variable and the interaction between three variables i.e. the concentration of MWCNT, electrodeposition potential and deposition time were studied and modeled. The statistical analysis showed that the concentration of MWCNT and deposition time have significantly affected the peak current response. A reduced cubic model equation with the coefficient of determination (R2) value of 0.9973 was developed. The optimized condition predicted by the software was compared with the experiment and resulting in less than 2% error, indicating that this model was reliable and able to predict the peak current response accurately. Additionally, the electrochemical properties, chemical properties and morphology of the optimized modified electrode were characterized by cyclic voltammetry (CV), Fourier transform infrared (FTIR), Raman spectroscopy and field emission scanning electron microscopy (FESEM). The peak current of the optimized PEDOT/MWCNT modified electrode was higher than electrode without MWCNT and the FESEM study demonstrated that the tubular structure of MWCNT was uniformly wrapped by PEDOT. The FTIR and Raman spectra proved that MWCNT was successfully incorporated into PEDOT.

Antioxidant and Wound Healing Activity of Polyherbal Fractions of Clinacanthus nutans and Elephantopus scaber

Elephantopus scaber and Clinacanthus nutans are traditionally used as wound healing herb. The objective of the present study is to develop a new polyherbal formulation, by comparison, the herbal combination of Elephantopus scaber and Clinacanthus nutans as an in vitro antioxidant activity with their individual herbal activity followed by fractionation of polyherbal formulation for in vivo wound healing activities and identification of bioactive compounds from their active fractions. Antioxidant activity was performed in vitro by DPPH scavenging antioxidant activity followed by in vivo wound healing activities using excision wound model, incision wound model, and burn wound model. Toxicity of the fractions of the polyherbal formulation was performed by a dermal toxicity test. The result showed that Elephantopus scaber crude extract on the basis of EC50 performs a much faster action (15.67 μg/mL) but with less % inhibition (87.66%) as compared to the combination of the new polyherbal formulation of crude extract (30 μg/mL). The polyherbal formulation has the highest % inhibition (89.49%) at the same dose as compared to Elephantopus scaber (87.66%). In comparison among all crude and fractions of new polyherbal formulation, it was found that the ethyl acetate fraction of polyherbal formulation has the fastest activity (EC50 14.83 μg/mL) with % inhibition (89.28%). Furthermore, during evaluation of wound contraction on excision and incision wound model, ethyl acetate fraction possesses the highest activity with (P < 0.001) and (P < 0.0001), respectively. During burn wound model, aqueous fraction (P < 0.001) possesses the highest activity followed by an ethyl acetate fraction (P < 0.0001). LC-MS analysis discovered the presence of several flavonoid-based compounds that work synergistically with sesquiterpene lactone and other bioactive compounds. In conclusion, flavonoid increases the antioxidant activity that surges the rate of wound contraction and works synergistically with other bioactive compounds.

Enhancing a clenbuterol immunosensor based on poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube performance using response surface methodology

Clenbuterol (CLB) is an illegal antibiotic for livestock, which is misused as a growth promoter drug. In this study, an immunosensor modified with poly(3,4-ethylenedioxythiophene) (PEDOT), multi-walled carbon nanotubes (MWCNT) and anti-clenbuterol antibody (Ab) was developed for the detection of CLB. A screen-printed carbon electrode (SPCE) was modified with PEDOT/MWCNT as a sensor platform before immobilizing Ab for specific CLB binding through a competitive-type immunoassay. Free CLB in the sample solution competed with clenbuterol-horseradish peroxide (CLB–HRP) to bind with Ab. A high current signal was obtained after optimization of the electrochemical immunoassay conditions (pH, incubation temperature, antigen (Ag) incubation time and % blocking) using the response surface methodology/central composite design (RSM/CCD). The developed immunosensor is highly reproducible and sensitive with good storage stability, which are necessary for practical application. In real sample application, this immunosensor produces comparable results with liquid chromatography-mass spectrometry; thus, it is useful for CLB screening and monitoring in real meat samples.

Development of Polyclonal Antibody against Clenbuterol for Immunoassay Application

Development of an immunoassay for clenbuterol (CLB) detection required an anti-CLB antibody as an important bioreceptor. In this study, we report our work on production and purification of a rabbit-derived polyclonal anti-CLB antibody. The antibody was then purified by nProtein A Sepharose affinity column and the antibody purity was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The activities of purified antibody were evaluated based on high antibody titer determined from enzyme-linked immunosorbent assay (ELISA). The sensitivity and selectivity of this antibody was evaluated and exhibits negligible cross-reactivity to antibiotics other than β-agonist families. Evaluation of the antibody as bioreceptor in immunoassay was performed using direct competitive ELISA and exhibited linear calibration plot (R2 = 0.9484). The antibody was used to detect the content of CLB in spiked milk samples and the recovery of more than 92% indicating significant performance as bioreceptor for the development of a rapid and simple immunoassay.

Goniothalamus: Phytochemical and Ethnobotanical Review

Goniothalamus species are used in widespread medicines for abortion, anti-aging, body pains, rheumatism, skin complaints, typhoid fever, tympanites, stomach ache and fever. The present study reviews the distribution of species along with their synonyms, their traditional usage, and correlated chemical compounds of Goniothalamus species with stress on the authentication of their ethnobotanical uses. The findings in some Goniothalamus species suggest that the chemical nature of their derivatives, such as acetogenins and styryl-lactones, may justify the use of these species against cancer in Asian traditional medicines due to their cytotoxic potential.