Central Composite Design for Optimization of Mitomycin C-Loaded Quantum Dots/Chitosan Nanoparticles as Drug Nanocarrier Vectors.

Cancer is one of the most devastating diseases that leads to a high degree of mortality worldwide. Hence, extensive efforts have been devoted to the development of drug nanocarrier vectors as a potential new cancer treatment option. The main goal of this treatment is to deliver an anticancer medicine successfully and effectively to the patient's cells using non-toxic nanocarriers. Here, we present a drug delivery system to emphasize the optimization of an anticancer drug-loaded formulation using Mitomycin C (MMC) encapsulated in chitosan nanocarrier conjugated with a bioimaging fluorescence probe of Mn:ZnS quantum dots (MMC@CS-Mn:ZnS). Additionally, the Response Surface Methodology (RSM), which uses a quadratic model to forecast the behaviour of the nano-drug delivery system, was used to assess the optimization of encapsulation efficiency. In this investigation, the core points of the Central Composite Design (CCD) model were used with 20 runs and 6 replications. The encapsulation efficiency (EE%) was measured using UV-Vis spectroscopy at 362 nm. The highest EE% is 55.31 ± 3.09 under the optimum parameters of incubation time (105 min), concentration of MMC (0.875 mg/mL), and concentration of nanocarriers (5.0 mg/mL). Physicochemical characterizations for the nanocarriers were accessed using a nanosizer and field-emission scanning electron microscopy (FESEM). Three independent variables for the evaluation of the encapsulation efficiency were used, in which the incubation time, concentration of MMC, concentration of nanocarriers, and correlation for each variable were studied. Furthermore, the MMC drug release efficiency was carried out in four different solution pHs of 5.5, 6.0, 6.5, 7.0, and pH 7.5, and the highest cumulative drug release of 81.44% was obtained in a pH 5.5 release medium, followed by cumulative releases of 68.55%, 50.91%, 41.57%, and 32.45% in release mediums with pH 6.0, pH 6.5, pH 7.0, and pH 7.5. Subsequently, five distinct mathematical models-pseudo-first-order, pseudo-second-order, Hixson-Crowell, Korsmeyer-Peppas, and Higuchi kinetic models-were used to fit all of the drug release data. The Korsmeyers-Peppas model was found to fit it well, highlighting its importance for the log of cumulative drug release proportional to the log of time at the equilibrium state. The correlation coefficient value (R2) was obtained as 0.9527, 0.9735, 0.9670, 0.9754, and 0.9639 for the drug release in pH 5.5, pH 6.0, pH 6.5, pH 7.0, and pH 7.5, respectively. Overall, from the analysis, the as-synthesized MMC nanocarrier (MMC@CS-Mn:ZnS) synergistically elucidates the underlying efficient delivery of MMC and leverages the drug loading efficiency, and all these factors have the potential for the simultaneous curbing of non-muscle invasive bladder cancer reoccurrence and progression when applied to the real-time disease treatment.

Drug Release Profiles of Mitomycin C Encapsulated Quantum Dots-Chitosan Nanocarrier System for the Possible Treatment of Non-Muscle Invasive Bladder Cancer.

Nanotechnology-based drug delivery systems are an emerging technology for the targeted delivery of chemotherapeutic agents in cancer therapy with low/no toxicity to the non-cancer cells. With that view, the present work reports the synthesis, characterization, and testing of Mn:ZnS quantum dots (QDs) conjugated chitosan (CS)-based nanocarrier system encapsulated with Mitomycin C (MMC) drug. This fabricated nanocarrier, MMC@CS-Mn:ZnS, has been tested thoroughly for the drug loading capacity, drug encapsulation efficiency, and release properties at a fixed wavelength (358 nm) using a UV-Vis spectrophotometer. Followed by the physicochemical characterization, the cumulative drug release profiling data of MMC@CS-Mn:ZnS nanocarrier (at pH of 6.5, 6.8, 7.2, and 7.5) were investigated to have the highest release of 56.48% at pH 6.8, followed by 50.22%, 30.88%, and 10.75% at pH 7.2, 6.5, and 7.5, respectively. Additionally, the drug release studies were fitted to five different pharmacokinetic models including pesudo-first-order, pseudo-second-order, Higuchi, Hixson-Crowell, and Korsmeyers-Peppas models. From the analysis, the cumulative MMC release suits the Higuchi model well, revealing the diffusion-controlled mechanism involving the correlation of cumulative drug release proportional to the function square root of time at equilibrium, with the correlation coefficient values (R2) of 0.9849, 0.9604, 0.9783, and 0.7989 for drug release at pH 6.5, 6.8, 7.2, and 7.5, respectively. Based on the overall results analysis, the formulated nanocarrier system of MMC synergistically envisages the efficient delivery of chemotherapeutic agents to the target cancerous sites, able to sustain it for a longer time, etc. Consequently, the developed nanocarrier system has the capacity to improve the drug loading efficacy in combating the reoccurrence and progression of cancer in non-muscle invasive bladder diseases.

DNA Electrochemical Biosensor Based on Iron Oxide/Nanocellulose Crystalline Composite Modified Screen-Printed Carbon Electrode for Detection of Mycobacterium tuberculosis.

Death from tuberculosis has resulted in an increased need for early detection to prevent a tuberculosis (TB) epidemic, especially in closed and crowded populations. Herein, a sensitive electrochemical DNA biosensor based on functionalized iron oxide with mercaptopropionic acid (MPA-Fe3O4) nanoparticle and nanocellulose crystalline functionalized cetyl trimethyl ammonium bromide (NCC/CTAB) has been fabricated for the detection of Mycobacterium tuberculosis (MTB). In this study, a simple drop cast method was applied to deposit solution of MPA-Fe3O4/NCC/CTAB onto the surface of the screen-printed carbon electrode (SPCE). Then, a specific sequence of MTB DNA probe was immobilized onto a modified SPCE surface by using the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling mechanism. For better signal amplification and electrochemical response, ruthenium bipyridyl Ru(bpy)32+ was assigned as labels of hybridization followed by the characteristic test using differential pulse voltammetry (DPV). The results of this biosensor enable the detection of target DNA until a concentration as low as 7.96 × 10-13 M with a wide detection range from 1.0 × 10-6 to 1.0 × 10-12 M. In addition, the developed biosensor has shown a differentiation between positive and negative MTB samples in real sampel analysis.

Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor.

In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM-1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.

Selective and simultaneous detection of cadmium, lead and copper by tapioca-derived carbon dot-modified electrode.

The need for the sensing of environmental pollutants cannot be overemphasized in the twenty-first century. Herein, a sensor has been developed for the sensitive and selective detection of copper (Cu2+), lead (Pb2+) and cadmium (Cd2+) as major heavy metals polluting water environment. A screen-printed carbon electrode (SPCE) modified by fluorescent carbon dots (CDs) and gold nanoparticles (AuNPs) was successfully fabricated for sensing Cu2+, Pb2+ and Cd2+. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were deployed for the analysis of ternary analytes. CV was set at a potential range of - 0.8 to + 0.2 V at a scan rate of 100 mV/s, and DPV at a potential range of - 0.8 to + 0.1 V, scan rate of 50 mV/s, pulse rate of 0.2 V and pulse width of 50 ms. DPV technique was applied through the modified electrode for sensitive and selective determination of Cu2+, Pb2+ and Cd2+ at a concentration range of 0.01 to 0.27 ppm for Cu2+, Pb2+ and Cd2+. Tolerance for the highest possible concentration of foreign substances such as Mg2+, K+, Na+, NO3-, and SO42- was observed with a relative error less than ± 3%. The sensitivity of the modified electrode was at 0.17, 0.42 and 0.18 ppm for Cd2+, Pb2+ and Cu2+, respectively, while the limits of detection (LOD) achieved for cadmium, lead and copper were 0.0028, 0.0042 and 0.014 ppm, respectively. The quality of the modified electrode for sensing Cu2+, Pb2+ and Cd2+ at trace levels is in accordance with the World Health Organization (WHO) and Environmental Protection Agency (EPA) water regulation standard. The modified SPCE provides a cost-effective, dependable and stable means of detecting heavy metal ions (Cu2+, Pb2+ and Cd2+) in an aqueous solution. Graphical abstract .

Label-free optical spectroscopy for characterizing binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite towards nickel ion.

Surface plasmon resonance (SPR) is a label-free optical spectroscopy that is widely used for biomolecular interaction analysis. In this work, SPR was used to characterize the binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite (CTA-NCC/GO) towards nickel ion. The formation of CTA-NCC/GO nanocomposite has been confirmed by FT-IR. The SPR analysis result shows that the CTA-NCC/GO has high binding affinity towards Ni2+ from 0.01 until 0.1 ppm with binding affinity constant of 1.620 × 103 M-1. The sensitivity for the CTA-NCC/GO calculated was 1.509°â€¯ppm-1. The full width at half maximum (FWHM), data accuracy (DA), and signal-to-noise ratio (SNR) have also been determined using the obtained SPR curve. For the FWHM, the value was 2.25° at 0.01 until 0.08 ppm and decreases to 2.12° at 0.1 until 10 ppm. The DA for the SPR curves is the highest at 0.01 until 0.08 ppm and lowest at 0.1 until 10 ppm. The SNR curves mirrors the curves of SPR angle shift where the SNR increases with the Ni2+ concentrations. For the selectivity test, the CTA-NCC/GO has the abilities to differentiate Ni2+ in the mixture of metal ions.

Histological analysis of anti-cancer drug loaded, targeted Mn:ZnS quantum dots in metastatic lesions of 4T1 challenged mice.

5-Fluororaucil (5-FU) as anti-cancer drug was reported to induce thymidine synthase (TS) overexpression and cancer cell resistance. To improve its therapeutic efficacy and selective targeting, here we developed a targeted delivery system mediated by the active ligand-folate receptor chemistry to deliver the 5-FU drug selectively into the tumor microenvironment. The preparation was achieved by exploring chitosan (CS)-biopolymer based system with folic acid (FA)-conjugation. The 5-FU@FACS-Mn:ZnS quantum dots (QDs) based on the histological assessment conducted in the 4T1 challenged mice showed an improved tumor remission in the liver, spleen and lungs. The 5-FU@FACS-Mn:ZnS composite induced anti-proliferative properties in these organs as compared to the free 5-FU drug. Unlike the 5-FU@FACS-Mn:ZnS treated groups which showed some specific morphological changes such as cell shrinkage without obvious presence of adipocytes, the excised section of the tumor in the untreated control group and the free 5-FU drug treated group showed necrotic and degenerated cells; these cells are multifocally distributed in the tumor mass with evidence of widely distributed adipocytes within the tumor mass. These findings suggest that the 5-FU@FACS-Mn:ZnS composite has a superior role during the induction of apoptosis in the 4T1 cells as compared to the free 5-FU drug treated groups. The results of the study therefore suggest that the impregnation of 5-FU anti-cancer drug within the FACS-Mn:ZnS system significantly improves its selective targeting efficacy, in addition to improving the anti-proliferative properties and attenuate possible tumor resistances to the 5-FU drug. The work discusses about the anti-metastatic effects of folic acid-bound 5-Fluororacil loaded Mn:ZnS quantum dots towards 4T1 cell line proliferation in mice based on the histological analysis.

Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose.

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection technique. The formation of ZnS shell at the outer surface of CdSe core was made via a specific process namely, SILAR (successive ionic layer adsorption and reaction). The distribution, morphology, and optical characteristics of the prepared core-shell QDs were assessed by transmission electron microscopy (TEM) and spectrofluorescence, respectively. From the analysis, the results show that the mean particle size of prepared QDs is in the range of 10-12 nm and that the optimum emission condition was displayed at 620 nm. Further, the prepared CdSe/ZnS core shell QDs were modified by means of a room temperature ligand-exchange method that involves six organic ligands, L-cysteine, L-histidine, thio-glycolic acid (TGA or mercapto-acetic acid, MAA), mercapto-propionic acid (MPA), mercapto-succinic acid (MSA), and mercapto-undecanoic acid (MUA). This process was chosen in order to maintain a very dense water solubilizing environment around the QDs surface. From the analysis, the results show that the CdSe/ZnS capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence emission as compared to others; hence, it was tested further for the glucose detection after their treatment with glucose oxidase (GOx) and horseradish peroxidase (HRP) enzymes. Here in this study, the glucose detection is based on the fluorescence quenching effect of the QDs, which is correlated to the oxidative reactions occurred between the conjugated enzymes and glucose. From the analysis of results, it can be inferred that the resultant GOx:HRP/CdSe/ZnS-TGA QDs system can be a suitable platform for the fluorescence-based determination of glucose in the real samples.

Oil palm fiber biodegradation: physico-chemical and structural relationships.

MAIN CONCLUSION: X-ray microtomography results revealed that delignification process damaged the oil palm fibers, which correlated well with reduction of lignin components and increase of the phenolic content. Biodegradation investigation of natural fibers normally focuses on physico-chemical analysis, with less emphasis on physical aspect like fiber structures affect from microbial activity. In this work, the performance of Pycnoporus sanguineus to delignify oil palm empty fruit bunch fibers through solid-state fermentation utilizing various ratio of POME sludge was reported. In addition to tensile testing, physico-chemical and X-ray microtomography (µ-CT) analyses on the oil palm fibers were conducted to determine the effectiveness of the degradation process. The best ratio of fiber to fungi (60:40) was chosen based on the highest lignin loss and total phenolic content values and further investigation was performed to obtain fermentation kinetics data of both laccase and manganese peroxidase. µ-CT results revealed that delignification process damaged the pre-treated and untreated fibers structure, as evident from volume reduction after degradation process. This is correlated with reduction of lignin component and increase of the phenolic content, as well as lower stress-strain curves of the pre-treated fibers compared to the untreated ones (from tensile testing). It is suggested that P. sanguineus preferred to consume the outer layer of the fiber, before it penetrates through the cellular structure of the inner fiber.

Patterned Array of Poly(ethylene glycol) Silane Monolayer for Label-Free Detection of Dengue.

In the present study, the construction of arrays on silicon for naked-eye detection of DNA dengue was demonstrated. The array was created by exposing a polyethylene glycol (PEG) silane monolayer to 254 nm ultraviolet (UV) light through a photomask. Formation of the PEG silane monolayer and photomodifed surface properties was thoroughly characterized by using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The results of XPS confirmed that irradiation of ultraviolet (UV) light generates an aldehyde functional group that offers conjugation sites of amino DNA probe for detection of a specific dengue virus target DNA. Employing a gold enhancement process after inducing the electrostatic interaction between positively charged gold nanoparticles and the negatively charged target DNA hybridized to the DNA capture probe allowed to visualize the array with naked eye. The developed arrays demonstrated excellent performance in diagnosis of dengue with a detection limit as low as 10 pM. The selectivity of DNA arrays was also examined using a single base mismatch and noncomplementary target DNA.

In vivo tumor targeting and anti-tumor effects of 5-fluororacil loaded, folic acid targeted quantum dot system.

In this study, we modulated the anti-cancer efficacy of 5-Fluorouracil (5-FU) using a carrier system with enhanced targeting efficacy towards folate receptors (FRs) expressing malignant tissues. The 5-FU drug was loaded onto Mn-ZnS quantum dots (QDs) encapsulated with chitosan (CS) biopolymer and conjugated with folic acid (FA) based on a simple wet chemical method. The formation of 5-FU drug loaded composite was confirmed using Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Furthermore, the in vivo biodistribution and tumor targeting specificity of the 5-FU@FACS-Mn:ZnS in the tumor-bearing mice was conducted based on the Zn(2+) tissue bioaccumulation using inductively coupled plasma (ICP) spectroscopy. In addition to the characterization, the in vitro release profile of 5-FU from the conjugates investigated under diffusion controlled method demonstrated a controlled release behaviour as compared against the release behaviour of free 5-FU drug. The as-synthesized 5-FU@FACS-Mn:ZnS nanoparticle (NP) systemically induced higher level of apoptosis in breast cancer cells in vitro as compared to cells treated with free 5-FU drug following both cell cycle and annexin assays, respectively. Also, the in vivo toxicity assessment of the 5-FU@FACS-Mn:ZnS NPs as compared to the control did not cause any significant increase in the activities of the liver and kidney function biomarkers, malondialdehyde (MDA) and nitric oxide (NO) levels. However, based on the FA-FRs chemistry, the 5-FU@FACS-Mn:ZnS NPs specifically accumulated in the tumor of the tumor-bearing mice and thus contributed to the smaller tumor size and less event of metastasis was observed in the lungs when compared to the tumor-bearing mice groups treated with the free 5-FU drug. In summary, the results demonstrated that the 5-FU@FACS-Mn:ZnS QDs exhibits selective anti-tumor effect in MDA-MB231 breast cancer cells in vitro and 4TI breast cancer cells in vivo, providing a blueprint for improving the 5-FU efficacy and tumor targeting specificity with limited systemic toxicity.

Micromechanical modelling of oil palm empty fruit bunch fibres containing silica bodies.

Experimental and numerical investigation was conducted to study the micromechanics of oil palm empty fruit bunch fibres containing silica bodies. The finite viscoelastic-plastic material model called Parallel Rheological Network model was proposed, that fitted well with cyclic and stress relaxation tensile tests of the fibres. Representative volume element and microstructure models were developed using finite element method, where the models information was obtained from microscopy and X-ray micro-tomography analyses. Simulation results showed that difference of the fibres model with silica bodies and those without ones is larger under shear than compression and tension. However, in comparison to geometrical effect (i.e. silica bodies), it is suggested that ultrastructure components of the fibres (modelled using finite viscoelastic-plastic model) is responsible for the complex mechanical behaviour of oil palm fibres. This can be due to cellulose, hemicellulose and lignin components and the interface behaviour, as reported on other lignocellulosic materials.

Folic acid targeted Mn:ZnS quantum dots for theranostic applications of cancer cell imaging and therapy.

In this study, we synthesized a multifunctional nanoparticulate system with specific targeting, imaging, and drug delivering functionalities by following a three-step protocol that operates at room temperature and solely in aqueous media. The synthesis involves the encapsulation of luminescent Mn:ZnS quantum dots (QDs) with chitosan not only as a stabilizer in biological environment, but also to further provide active binding sites for the conjugation of other biomolecules. Folic acid was incorporated as targeting agent for the specific targeting of the nanocarrier toward the cells overexpressing folate receptors. Thus, the formed composite emits orange-red fluorescence around 600 nm and investigated to the highest intensity at Mn(2+) doping concentration of 15 at.% and relatively more stable at low acidic and low alkaline pH levels. The structural characteristics and optical properties were thoroughly analyzed by using Fourier transform infrared, X-ray diffraction, dynamic light scattering, ultraviolet-visible, and fluorescence spectroscopy. Further characterization was conducted using thermogravimetric analysis, high-resolution transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy. The cell viability and proliferation studies by means of MTT assay have demonstrated that the as-synthesized composites do not exhibit any toxicity toward the human breast cell line MCF-10 (noncancer) and the breast cancer cell lines (MCF-7 and MDA-MB-231) up to a 500 µg/mL concentration. The cellular uptake of the nanocomposites was assayed by confocal laser scanning microscope by taking advantage of the conjugated Mn:ZnS QDs as fluorescence makers. The result showed that the functionalization of the chitosan-encapsulated QDs with folic acid enhanced the internalization and binding affinity of the nanocarrier toward folate receptor-overexpressed cells. Therefore, we hypothesized that due to the nontoxic nature of the composite, the as-synthesized nanoparticulate system can be used as a promising candidate for theranostic applications, especially for a simultaneous targeted drug delivery and cellular imaging.

Study on the spectrophotometric detection of free fatty acids in palm oil utilizing enzymatic reactions.

In this paper, a comprehensive study has been made on the detection of free fatty acids (FFAs) in palm oil via an optical technique based on enzymatic aminolysis reactions. FFAs in crude palm oil (CPO) were converted into fatty hydroxamic acids (FHAs) in a biphasic lipid/aqueous medium in the presence of immobilized lipase. The colored compound formed after complexation between FHA and vanadium (V) ion solution was proportional to the FFA content in the CPO samples and was analyzed using a spectrophotometric method. In order to develop a rapid detection system, the parameters involved in the aminolysis process were studied. The utilization of immobilized lipase as catalyst during the aminolysis process offers simplicity in the product isolation and the possibility of conducting the process under extreme reaction conditions. A good agreement was found between the developed method using immobilized Thermomyces lanuginose lipase as catalyst for the aminolysis process and the Malaysian Palm Oil Board (MPOB) standard titration method (R2 = 0.9453).