Hani A. Alhadrami

Aptamer-Based Microfluidic Electrochemical Biosensor for Monitoring Cell-Secreted Trace Cardiac Biomarkers

Continual monitoring of secreted biomarkers from organ-on-a-chip models is desired to understand their responses to drug exposure in a noninvasive manner. To achieve this goal, analytical methods capable of monitoring trace amounts of secreted biomarkers are of particular interest. However, a majority of existing biosensing techniques suffer from limited sensitivity, selectivity, stability, and require large working volumes, especially when cell culture medium is involved, which usually contains a plethora of nonspecific binding proteins and interfering compounds. Hence, novel analytical platforms are needed to provide noninvasive, accurate information on the status of organoids at low working volumes. Here, we report a novel microfluidic aptamer-based electrochemical biosensing platform for monitoring damage to cardiac organoids. The system is scalable, low-cost, and compatible with microfluidic platforms easing its integration with microfluidic bioreactors. To create the creatine kinase (CK)-MB biosensor, the microelectrode was functionalized with aptamers that are specific to CK-MB biomarker secreted from a damaged cardiac tissue. Compared to antibody-based sensors, the proposed aptamer-based system was highly sensitive, selective, and stable. The performance of the sensors was assessed using a heart-on-a-chip system constructed from human embryonic stem cell-derived cardiomyocytes following exposure to a cardiotoxic drug, doxorubicin. The aptamer-based biosensor was capable of measuring trace amounts of CK-MB secreted by the cardiac organoids upon drug treatments in a dose-dependent manner, which was in agreement with the beating behavior and cell viability analyses. We believe that, our microfluidic electrochemical biosensor using aptamer-based capture mechanism will find widespread applications in integration with organ-on-a-chip platforms for in situ detection of biomarkers at low abundance and high sensitivity.

Aptamer-Based Label-Free Impedimetric Biosensor for Detection of Progesterone

Rising progesterone (P4) levels in humans due to its overconsumption through hormonal therapy, food products, or drinking water can lead to many negative health effects. Thus, the simple and accurate assessment of P4 in both environmental and clinical samples is highly important to protect public health. In this work, we present the selection, identification, and characterization of ssDNA aptamers with high binding affinity to P4. The aptamers were selected in vitro from a single-stranded DNA library of 1.8 × 10(15) oligonucleotides showing dissociation constants (KD) in the low nanomolar range. The dissociation constant of the best aptamer, designated as P4G13, was estimated to be 17 nM by electrochemical impedance spectroscopy (EIS) as well as fluorometric assay. Moreover, the aptamer P4G13 did not show cross-reactivity to analogues similar to progesterone such as 17β-estradiol (E2) and norethisterone (NET). An impedimetric aptasensor for progesterone was then fabricated based on the conformational change of P4G13 aptamer, immobilized on the gold electrode by self-assembly, upon binding to P4, which results in an increase in electron transfer resistance. Aptamer-complementary DNA (cDNA) oligonucleotides were tested to maximize the signal gain of the aptasensor after binding with progesterone. Significant signal enhancement was observed when the aptamer hybridized with a short complementary sequence at specific site was used instead of pure aptamer. This signal gain is likely due to the more significant conformational change of the aptamer-cDNA than the pure aptamer upon binding with P4, as confirmed by circular dichroism (CD) spectroscopy. The developed aptasensor exhibited a linear range for concentrations of P4 from 10 to 60 ng/mL with a detection limit of 0.90 ng/mL. Moreover, the aptasensor was applied in spiked tap water samples and showed good recovery percentages. The new selected progesterone aptamers can be exploited in further biosensing applications for environmental, clinical, and medical diagnostic purposes.

Hydrogels 2.0: improved properties with nanomaterial composites for biomedical applications.

The incorporation of nanomaterials in hydrogels (hydrated networks of crosslinked polymers) has emerged as a useful method for generating biomaterials with tailored functionality. With the available engineering approaches it is becoming much easier to fabricate nanocomposite hydrogels that display improved performance across an array of electrical, mechanical, and biological properties. In this review, we discuss the fundamental aspects of these materials as well as recent developments that have enabled their application. Specifically, we highlight synthesis and fabrication, and the choice of nanomaterials for multifunctionality as ways to overcome current material property limitations. In addition, we review the use of nanocomposite hydrogels within the framework of biomedical and pharmaceutical disciplines.

Quantification of total phenol, flavonoid content and pharmacognostical evaluation including HPTLC fingerprinting for the standardization of Piper nigrum Linn fruits

ABSTRACT Objective: To carry out the physicochemical and phytochemical standardization with high performance thin layer chromatography fingerprinting of Piper nigrum L. (P. nigrum) fruits in order to ascertain the standard pharmacognostical parameters of this king of spices. Methods: Many standardization parameters like extractive values, total ash value, water soluble ash value and acid insoluble ash, moisture content, loss on drying and pH values of P. nigrum L. fruits were analyzed. The method of Harborne was adopted for the preliminary phytochemicals screening. Analysis of total phenolic and flavonoid contents, pesticides residues, aflatoxin and heavy metals were also performed. CAMAG-high performance thin layer chromatography system was used for fingerprinting of methanolic extract of P. nigrum L. fruits. Results: The results of phytochemicals testing indicated the presence of carbohydrates, phenolic compounds, flavonoids, alkaloids, proteins, saponins, lipids, sterols and tannins in various solvent extracts. Total phenolic and flavonoid contents in methanolic extract were found to be 1.728 1 mg/g and 1.087 μg/g, respectively. Heavy metals concentrations were found to be within standard limits. Aflatoxins and pesticides residues were absent. Conclusions: The outcome of this study might prove beneficial in herbal industries for identification, purification and standardization of P. nigrum L. fruits.

Hazard and risk assessment of human exposure to toxic metals using in vitro digestion assay

Abstract Clean-up targets for toxic metals require that the site be “fit for purpose”. This means that targets are set with respect to defined receptors that reflect intended land-use. In this study, the likely threat of human exposure to toxic metals has been evaluated by simulating the human digestion process in vitro. The effects of key attributes (i.e. sample fraction size, pH, Kd and total metal concentrations) on the bioavailability of Cu and Ni were also investigated. Total metal concentration was the key explanatory factor for Cu and Ni bioavailability. A comparative ranking of metal concentrations in the context of tolerable daily intakes for Cu and Ni confirmed that the pH has the greatest impact on metals bioavailability. Rapid screening of key attributes and total toxic metal doses can reveal the relative hazard imposed on human, and this approach should be considered when defining threshold values for human protection.

Validation of SOS-lux Microbial Biosensors for Mutagenicity Assessment:Mitomycin-C as a Model Compound

Human health protection requires relating the bioaccessible concentration of a mutagen with the corresponding likely harm that could be caused through exposure. This requires designating the target receptor in need of protection, and a quantitative understanding of the likely pathways for mutagen availability. In this study, young children were selected as target receptors because of their tendency to directly ingest soils. Most data used to characterise a chemical mutagenicity has been extrapolated from rat-based assays using chemical ingestion or direct injection procedures. Mitomycin C was selected as a relevant model compound and extracted using an established in vitro digestion technique. A range of mutagenic bioassays (i.e. SOS-lux based microbial biosensors and Salmonella mutagenicity assay) were calibrated and optimised in aqueous samples, before being applied to soil extracts. The biosensors were consistently as sensitive and responsive as the traditional Salmonella assay, however, the use of microbial biosensors offered speed and ease of analysis. The data presented confirm that the in vitro digestion bioassay enabled a rapid and inexpensive technique for deriving critical values for the protection of humans exposed to soil borne mutagenic pollutants.

The potential applicationsof SOS-luxbiosensors for rapid screening of mutagenic chemicals

Ritika Mohan received her B.Sc degree in Chemical Engineering from the University of Arizona, Tucson. She received her M.Sc in Chemical Engineering from the University of Illinois, Urbana-Champaign. Currently, she is in the fourth year of her Ph.D. at the same institution. Her current research efforts are in the area of microfluidics, including the development of pneumatic normally closed microvalves for integrated microfluidics and microfluidic devices for antibiotic susceptibility testing especially for polymicrobial infections.The medical field is a vastly expanding one and with the discovery of nanoparticles (carbon nanotubes, diamondoids, fullerenes, gold and silver nanoparticles, quantum dots, etc.), there lies a vast field of unsolved medical diagnoses to be reassessed. Upon reassessment of the current medical problems, it is important to know what happens to a particle once it is free in the body. This review examines the different destinations of nanomaterials after they enter the body, their toxicity and their filtration. Assessing the destination of nanoparticles is done in order to find out whether they are removed by macrophages. It is concluded the strongest trends of the nanoparticles itself is of shape and surface chemistry. Toxicity of nanoparticles is found to be mostly dose-dependent. The nanoparticle filtration goal is to have the body naturally filter out the nanoparticles without a response from the immune system.I this work, the author has developed the first ultra-effective photothermal agents for prostate cancer-targeted therapy. The newly synthesized probe was found to be intensely and specifically accumulated into all prostate cancer cells without any impact on the cell viability, resulting in tremendously efficient targeted therapy. To apply this probe for in vivo therapies, efforts have been made to overcome various problems, such as short half-life of the particles in the circulation, low permeability of them, and instability of aptamers in the blood. It is expected that successful further study makes aptamer-modified nanoparticles the promising in vivo therapeutic nanomaterials for the treatment of not only prostate cancers but also other carcinomas.

Ameliorative effect of camel's milk and Nigella Sativa Oil against thioacetamide-induced hepatorenal damage in rats

Background: Camel milk (CM) and Nigella sativa (NS) have been traditionally claimed to cure wide range of diseases and used as medicine in different part of world, particularly in Saudi Arabia. Several research studies have been published that proved beneficial effects of CM and NS. Objective: This study was undertaken to investigate the antihepatotxic potential of CM and NS oil (NSO) against thioacetamide (TAA)-induced hepato and nephrotoxicity in rats. Materials and Methods: Thirty female Albino Wistar rats were randomly divided in to six groups having five rats in each group. A single subcutaneous injection of TAA (100 mg/kg b. w.) was administered to all the rats in Group-II to VI on 1st day to induce hepatorenal damage. Group I served as a normal control while Group II served as toxic control for comparison purpose. Experimental animals in Group III, IV, and V were supplemented with fresh CM, (250 mL/24 h/cage), NSO (2 mL/kg/day p. o.), and NSO + fresh CM, respectively. Group VI was treated with a polyherbal hepatoprotective Unani medicine Jigreen (2 mL/kg/day p. o.) for 21 days. TAA-induced hepatorenal damage and protective effects of CM and NSO were assessed by analyzing liver and kidney function tests in the serum. Histopathology of liver and kidney tissues was also carried out to corroborate the findings of biochemical investigation. Results: The results indicated that the TAA intoxicated rats showed significant increase in the alanine transaminase, aspartate transaminase, gamma-glutamyl transpeptidase, alkaline phosphatase, lipid profile, urea, creatinine, uric acid, sodium, and potassium levels in serum. Treatment of rats with CM, NSO, and CM plus NSO combination and Jigreen significantly reversed the damage and brought down the serum biochemical parameters and lipid profile toward the normal levels. The histopathological studies also support the hepato and nephroprotective effects of CM and NSO. Conclusion: This study demonstrated the ameliorative effects of CM, NSO, and CM plus NSO combination against TAA-induced hepatorenal toxicity in rats. Abbreviations used: CM: Camel milk; NS: Nigella sativa; NSO: Nigella sativa Oil; TAA: Thioacetamide; S.C.: Subcutaneous; Jig: Jigreen; b.w.: Body Weight; mL: Milli liter; mg: Milli gram; g: Gram; Kg: Kilo gram; ALT: Alanine transaminase; AST: Aspartate transaminase; GGT: Gamma-Glutamyl Transpeptidase; ALP: Alkaline Phosphatase; TC: Total Cholesterol; HDL-C: High Density Lipoprotein Cholesterol; LDL-C: Low Density Lipoprotein Cholesterol; TG: Triglyceride; TB: Total bilirubin; K+: Potassium; Na+: Sodium; CCl4: Carbon Tetrachloride; °C: Degree Celsius; p.o.: Per Oral; RPM: Revolutions per minute; H&E: Hematoxylin and Eosin; SEM: Standard Error of Mean; ANOVA: The one-way analysis of variance.

Biosensors: Classifications, medical applications, and future prospective

Biosensors are devices that combine a biological material with a suitable platform for detection of pathogenic organisms, carcinogenic, mutagenic, and/or toxic chemicals or for reporting a biological effect. In recent years, an enormous number of different types of biosensors have been constructed and developed for several medical applications. The reason for that was primarily due to the numerous advantages and applications that can be offered by biosensors. This review article has been started with demonstrating the power of biosensor technologies versus analytical and conventional techniques. Subsequently, more emphasis has been added on the classification and the role of biosensors in several medical applications such as detection and monitoring of carcinogenic and mutagenic chemicals, reporting of endocrine disrupting compounds, and detection of pathogenic organisms. The most common reporter genes used in biosensors engineering and construction have also been summarized. Prospective strategies and recommendations for the future construction of biosensors have been highlighted.

Experimental studies and computer modeling of viscoelastic properties of heart valve leaflets: Implication in heart valve tissue engineering

Diseased or damaged heart valve leaflets are amongst the major causes of illness and death globally. The currently available treatment of heart valve patients is to mend the damaged valves, but in most severe cases, heart valves require replacement since repair is not feasible. The survival of the patient, as well as implantation success rate, depends on the engineered heart valves to instantly ensure adequate mechanical support and function after surgery. Therefore, the engineered heart valves must demonstrate and preserve the biomechanical properties similar to those of native heart valves. In the current project, we aim to improve our understanding of the structural, mechanical and viscoelastic properties of heart valve leaflets. We aim to develop a new computational model for simulation of viscoelastic properties of heart valve leaflets. In the work reported here, native bovine heart valve leaflets were excised from bovine hearts, collected from local slaughter house in Beirut and cryopreserved as necessary. The oscillatory shear based viscoelastic properties were studied using a parallel plate rheometer. The critical parameters such as, modulus of elasticity, ultimate tensile strength, maximum elongation and the stress-strain relationships as well as the oscillatory shear properties were investigated. Furthermore, an FEM based tri-layer composite model is being developed for computational studies of heart valve viscoelastic properties using finite element code ABAQUS. The developed model will be validated against the rheological behavior obtained from experiments. The new model and the obtained results will provide significant insights into the correlations between the nano-microstructure and biomechanics of the heart valves and their macroscale behaviors under different healthy and pathological conditions. The proper understanding of the correlations between nano-biomechanics and pathological conditions can also pave the ways for generations of new therapeutics for various cardiovascular diseases.