Harnessing the plasmonic properties of gold nanoparticles: functionalization strategies coupled with novel spectroscopic tools

Metallic plasmonic substrates such as gold nanoparticles (AuNPs) have fascinated researchers due to their usefulness in verious interdisciplinary studies at the interface between applied physics, biochemistry, engineering, and medicine. A good understanding of the physics of these noble nanostructures, particularly the plasmonic and optical properties, can be employed to improve a wide range of sensors and electronic devices. The relevance of molecular recognition and the binding of biological and chemical entities to diagnostics, biosensors, and drug delivery has attracted significant research interest. By addressing material functionalization design and advanced characterization methods, this doctoral work aims to highlight efforts to exploit the surface modification strategies to enhance the responsiveness of nanoparticle substrates for improved detection of health-relevant biomolecules. The self-assembly of small ligands, such as alkanethiols, and oligonucleotides on the surface of AuNPs provided a possible starting route for the preparation of bio-nanomaterials with precise physicochemical properties. The versatile AuNPs were optimized and thoroughly characterized by employing electron microscopy techniques such as transmission electron microscope (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM), spectroscopic techniques, including ultraviolet/visible (UV/Vis), dynamic light scattering (DLS), and thermal lens spectrometry (TLS), and biochemical assays (gel electrophoresis, Dot plot, Western plot, and the Enzyme Linked Immunosorbent Assay (ELISA)). Subsequently, the molecular recognition capabilities of functionalized AuNPs were investigated using multiple techniques, including novel detection routes such as the electrophoresis approach coupled with online TLS. This work establishes a versatile platform for AuNP engineering with controlled size and surface functionality. The strategies presented in this thesis aim to improve medical diagnostics to make them affordable for point-of-care scenarios to enhance the quality of human health.wide range of sensors and electronic devices. The relevance of molecular recognition and the binding of biological and chemical entities to diagnostics, biosensors, and drug delivery has attracted significant research interest. By addressing material functionalization design and advanced characterization methods, this doctoral work aims to highlight efforts to exploit the surface modification strategies to enhance the responsiveness of nanoparticle substrates for improved detection of health-relevant biomolecules. The self-assembly of small ligands, such as alkanethiols and oligonucleotides on the surface of AuNPs provided a possible starting route for the preparation of bio-nanomaterials with precise physicochemical properties. The versatile AuNPs were optimized and thoroughly characterized by employing electron microscopy techniques such as transmission electron microscope (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM), spectroscopic techniques, including ultraviolet/visible (UV/Vis), dynamic light scattering (DLS), and thermal lens spectrometry (TLS), and biochemical assays (gel electrophoresis, Dot plot, Western plot, and the Enzyme Linked Immunosorbent Assay (ELISA)). Subsequently, the molecular recognition capabilities of functionalized AuNPs were investigated using multiple techniques, including novel detection routes such as the electrophoresis approach coupled with online TLS. This work establishes a versatile platform for AuNP engineering with controlled size and surface functionality. The strategies presented in this thesis aim to improve medical diagnostics to make them affordable for point-of-care scenarios to enhance the quality of human health

Detection of Methylene Tetrahydrofolate Reductase Gene Polymorphism (C677T) In Sudanese Patients with Chronic Myeloid Leukemia

Chronic myeloid leukaemia (CML) is a kind of cancer that affects the white blood cells and resort to progress slowly through many years. It’s occur at any age, but is most common in older (60-65 years) of age. This is a cross sectional study aimed to detect MTHFR gene polymorphism (C677T) among Sudanese patients diagnosed with Chronic Myeloid Leukaemia and conducted at the research laboratory of the national center of neurological sciences (NCNS), Khartoum, Sudan.50 patients with Chronic Myeloid Leukemia (CML) diagnosed as BCR-ABL positive by RT-PCR used as a cases and 50 apparently healthy individuals as a control. A 5 ml of blood samples were collected in EDTA anticoagulant container for DNA Extraction and white blood cells count, hemoglobin level and platelets count. Genotyping of the MTHFR was carried out using PCR technique and the SNP (C677T) confirmed by sequencing a subset of samples. The results were analyzed using bioinformatics tools. The results showed; the most affected age group in the patients was 51-60 years followed by 41-50 years which constituted 32% and 30%, respectively. The hematological findings revealed that, the mean of TWBCs was 47.4, HB was 11.9 for patients, 7.2 and 14.1 respectively for control group (P = 0.000). PLT was 313.5 for patients and 287.5 for control group (P = 0.187). MTHFR gene was detected in the all patients (198pb) by the PCR, Sequence results were aligned with the reference sequence of MTHFR gene, the polymorphic C >T was found to be matched with the registered mutation in NCBI data base. This study provides the first evidence for associations of MTHFR gene polymorphism with the risk of chronic myeloid leukemia in Sudanese patients. The C >T genotype of the rs 677 polymorphism in MTHFR gene may have a promoting effect on chronic myeloid leukemia. Keywords: Chronic myeloid leukaemia (CML), DNA, PCR, RT-PCR, MTHF

Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor

Even though several studies have demonstrated the use of Indium Tin Oxides (ITO) as an extended gate field effect transistor (EGFET), the effect of different doses of gamma radiation on the intrinsic properties of the ITO films has not been considered. This study investigates the effect of gamma irradiation on the structural, optical, morphological and electrical properties as well as pH sensitivity (as an extended gate field effect transistor) of ITO thin films. ITO thin films with thickness of 400 nm were prepared using a radio frequency sputtering technique. The samples were then subjected to various doses of gamma radiation from a Co-60 radio-isotope (0.5 kGy, 1 kGy, 1.5 kGy, and 2 kGy). The structural and morphological changes as well as transmission and absorption of the thin films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Field-Emission Scanning Electron Microscope (FESEM) and UV–Vis spectrophotometry, before and after irradiation. The irradiated ITO thin films were then used as an extended gate field effect transistor to determine its ability to improve sensitivity as pH sensors. The grain size and transmittance in the range 300–900 nm of the ITO films were found to decrease with increasing gamma irradiation dose. In contrast, the uniformity and surface roughness of ITO thin films increased with increasing gamma radiation dose due to the formation of lattice defects. Moreover, the electrical resistance of the thin films increased with increasing dose because of the low current density and high number of surface defects associated with irradiation. The pH sensitivity of the ITO thin films improved after irradiation, possibly due to the concomitant increase in surface roughness with increasing radiation dose. The improvements in the pH sensitivity of ITO thin films after irradiation justify their potential use as pH sensors. Keywords: Indium Tin Oxide, Thin films, Gamma irradiation, Optical band gap, X-ray diffraction, EGFET, pH senso

the significant effect of size and concentrations of iron oxide nanoparticles on magnetic resonance imaging contrast enhancement

In this study, iron oxide (γ-Fe2O3) nanoparticles (IONs) were successfully synthesized using sol-gel method, and characterized by XRD and VSM. The potential application of the differently sized IONs (22 nm and 30 nm) as magnetic resonance imaging (MRI) contrast agents was investigated. The relaxation time (T2) of the IONs was measured at room temperature and concentration range of 9–84 µg/ml using fast spin echo sequence with six echoes. The size was found to affect the contrast enhancement of the MRI image, with the T2 for 22 nm sized γ-Fe2O3 nanoparticles exhibiting a shorter dephasing compared to the 30 nm sized γ-Fe2O3 nanoparticles. The T2 relaxivity also decreased with increasing concentration (9–84 µg/ml) of the γ-Fe2O3 nanoparticles. Based on the T2-weighted analysis, a better signal (i.e. brighter image) was achieved for the 30 nm sized γ-Fe2O3 nanoparticles. Thus, the use of IONs to enhance MR image contrast is dependent on the nanoparticle size and concentration of the IONs. In general, the results indicate that the synthesized γ-Fe2O3 nanoparticles are promising materials for use as MRI contrast agents. Keywords: Magnetic resonance imaging, Iron oxides nanoparticles, T2 relaxivity, XRD, VS

Production of insulin producing cells from cord blood mesenchymal stem cells and their potential in cell therapy

Introduction: Mesenchymal stem cells (MSCs) were described as adherent cells with a fibroblast-like appearance, have a great capacity for self-renewal while maintaining their multipotency and differentiation into multiple tissues in vivo and in vitro. Methods: MSCs were isolated from cord blood of Sudanese donors using Ficoll-Hypaque gradient density protocol, and differentiate into β- like cells using 3-step protocol. STZ induced diabetic rats were injected intraperitoneally with the differentiated islet β- like cells and blood glucose levels were monitored for seven days. Results: The adherent cell appeared round and sphere after one-week of incubation, and the fibroblast-like colony was strongly attached after three weeks of seeding. The phenotyping of cells showed positivity for CD13, and negativity for CD34, CD45 and HLADR. MSCs were induced into islet-like cells using a 3-step (15-days) protocol. The differentiated cells showed positive diathizone stain and positive imuno-reactivity to anti-human insulin antibody. Secretion of insulin by insulin-producing cells showed positive result with >3.4 u/ml scale reading in high glucose concentration medium. After one-week of transplantation the level of blood glucose was reduced from 410 to 225 mg/dl in the experimental rat. Conclusion: Human UCB-MSCs can be differentiated into insulin-secreting cells invitro, and are able to produce and secrete insulin in response to high glucose concentration in vivo and in vitro. Keywords: Cord blood, Mesenchymal stem cell, islets β-like cell

Detection of kidney complications relevant concentrations of ammonia gas using plasmonic biosensors : A review

Kidney-related health problems cause millions of deaths around the world annually. Fortunately, most kidney problems are curable if detected at the earliest stage. Continuous monitoring of ammonia from exhaled breath is considered as a replacement for the conventional blood-based monitoring of chronic kidney disease (CKD) and kidney failure owing to its cost effectiveness, non-invasiveness, excellent sensitivity, and capabilities for real-time measurement. The detection of ammonia for renal failure requires a biosensor with a detection limit of 1000 ppb (1 ppm). Among biosensors, plasmonic biosensors have attracted considerable research interest due to their potential for ultra-sensitivity, single particle/molecular level detection capability, multiplexing capability, photostability, real-time measurement, label-free measurement, room temperature operation, naked-eye readability, ease of miniaturization via simple sensor chip fabrication, and instrumentation, among other features. In this review, plasmonic sensors for the detection of ammonia gas relevant to kidney problems (LOD ≤ 1 ppm) are reviewed. In addition, the utilized strategies and surface functionalization for the plasmonic sensor are highlighted. Moreover, the main limitations of the reported sensors are stated for the benefit of future researchers. Finally, the challenges and prospects of plasmonic-based ammonia gas biosensors for potential application in the monitoring and screening of renal (kidney) failure, as well as the endpoint of the dialysis session, are stated

Identification and determination of antibiotic resistance of pathogenic bacteria Isolated from Septic Wounds

Wound infection is a global cause of morbidity and mortality across all wound types. Therefore, efficient diagnosis and treatment of wound infection are essential. This study was carried out to identify the pathogenic bacteria in infected wounds of the patient’s attending Sebha city hospitals (Libya) and to determine their resistance profile to the most common antibiotics used in therapy. A total of sixty wound swab specimens were collected and cultured, of which 39 samples showed bacterial growth. Three different species of bacteria were isolated. Staphylococcus aureus 21 (53.9%) were the most common organisms followed by Pseudomonas aeruginosa 10 (25.6%) and Staphylococcus epidermidis 8 (20.5%). The antibiotic susceptibility test of the bacterial isolate was performed by Kirby-Bauer disk diffusion method. Results showed that 90.5% of the Staphylococcus aureus isolates were resistant to vancomycin, 61.9% to tetracycline, 57.1% to amoxicillin, 52.4 % to methicillin, 42.9 to erythromycin and 23.8% to streptomycin. 87.5% of the Staphylococcus epidermidis isolates were resistant to vancomycin, 75% to methicillin, 62.5% to tetracycline, 50% to streptomycin 37.5% to amoxicillin, and erythromycin. All the Pseudomonas aeruginosa isolates were sensitive to ciprofloxacin and highly resistant 90-100% to other antibiotics tested Amoxicillin, Nalidixic acid, Streptomycin, and Tetracycline. The high rate of multiple antibiotic resistance was observed in all bacterial species recovered

Label-Free, Rapid and Facile Gold-Nanoparticles-Based Assay as a Potential Spectroscopic Tool for Trastuzumab Quantification

Monoclonal antibody-based immunotherapy is one of the pillars of cancer treatment. However, for an efficient and personalized approach to the therapy, a quantitative evaluation of the right dose for each patient is required. In this study, we developed a simple, label-free, and rapid approach to quantify Trastuzumab, a humanized IgG1 monoclonal antibody used against human epidermal growth factor receptor 2 (HER2), overexpressed in breast cancer patients, based on localized surface plasmon resonance (LSPR). The central idea of this work was to use gold nanoparticles (AuNPs) as plasmonic scaffolds, decorated with HER2 binders mixed with oligo-ethylene glycol (OEG) molecules, to tune the surface density of the attached macromolecules and to minimize nonspecific binding events. Specifically, we characterized and optimized a self-assembled monolayer of mixed alkylthiols terminated with nitrilotriacetic acid (NTA), and OEG3 as a spacing ligand to achieve both excellent dispersibility and high reliability in protein immobilization. The successful immobilization of histidine-tagged HER2 (His-tagged HER2) on NTA via cobalt (II) chelates was demonstrated, confirming the fully functional attachment of the proteins to the AuNP surface. The proposed design demonstrates the capability of producing a clear readout that enables the transduction of a Trastuzumab/HER2 binding event into optical signals based on the wavelength shifts in LSPR, which allowed for detecting clinically relevant concentrations of Trastuzumab down to 300 ng/mL in the buffer and 2 µg/mL in the diluted serum. This strategy was found to be fast and highly specific to Trastuzumab. These findings make the present platform an auspicious tool for developing affordable bio-nanosensors

Label-Free, Rapid and Facile Gold-Nanoparticles-Based Assay as a Potential Spectroscopic Tool for Trastuzumab Quantification

7noMonoclonal antibody-based immunotherapy is one of the pillars of cancer treatment. However, for an efficient and personalized approach to the therapy, a quantitative evaluation of the right dose for each patient is required. In this study, we developed a simple, label-free, and rapid approach to quantify Trastuzumab, a humanized IgG1 monoclonal antibody used against human epidermal growth factor receptor 2 (HER2), overexpressed in breast cancer patients, based on localized surface plasmon resonance (LSPR). The central idea of this work was to use gold nanoparticles (AuNPs) as plasmonic scaffolds, decorated with HER2 binders mixed with oligoethylene glycol (OEG) molecules, to tune the surface density of the attached macromolecules and to minimize nonspecific binding events. Specifically, we characterized and optimized a self-assembled monolayer of mixed alkylthiols terminated with nitrilotriacetic acid (NTA), and OEG3 as a spacing ligand to achieve both excellent dispersibility and high reliability in protein immobilization. The successful immobilization of histidine-tagged HER2 (His-tagged HER2) on NTA via cobalt (II) chelates was demonstrated, confirming the fully functional attachment of the proteins to the AuNP surface. The proposed design demonstrates the capability of producing a clear readout that enables the transduction of a Trastuzumab/HER2 binding event into optical signals based on the wavelength shifts in LSPR, which allowed for detecting clinically relevant concentrations of Trastuzumab down to 300 ng/mL in the buffer and 2 µg/mL in the diluted serum. This strategy was found to be fast and highly specific to Trastuzumab. These findings make the present platform an auspicious tool for developing affordable bio-nanosensors.openopenAhmed Alsadig, Hendrik Vondracek, Paolo Pengo, Lucia Pasquato, Paola Posocco, Pietro Parisse, Loredana CasalisAhmed, Alsadig; Vondracek, Hendrik; Pengo, Paolo; Pasquato, Lucia; Posocco, Paola; Parisse, Pietro; Casalis, Loredan

Referral pattern of oral and maxillofacial surgery cases in Sudan: A retrospective age-and sex-specific analysis of 3,478 patients over four years.

Oral and maxillofacial surgery (OMFS) is a specialty widening in its scope. An objective analysis of the referral pattern can provide essential information to improve healthcare. This four-year retrospective study was implemented in Khartoum Teaching Dental Hospital. Data (age, sex, diagnosis, and type of treatment) were collected from patient records. Disease frequency, as well as the effect of sex and age, were analyzed for each group. The frequency of treatment types was also assessed. Data were collected from a total of 3,478 patients over the four-year study period. There was a male predominance with the third decade of life being the most common age group. Pathological diseases were the most common (37%) reason for referral, followed by trauma (31%). Temporomandibular joint (TMJ) disorders and dentoalveolar extraction were the least frequently observed. Open reduction and internal fixation (ORIF) was the most commonly performed procedure (28%). These data represent the epidemiology of oral and maxillofacial diseases in Sudan. Given that the third decade of life is the most represented age group, it is beneficial to learn the long-term consequences of these diseases in these young patients and to use modern surgical techniques to improve their lives