Assessment of mycolic acids as ligand for nanoencapsulated anti-tuberculosis drug targeting

South Africa currently has the highest incidence of TB per 100 000 people in the world. In 2007 alone 112 000 people died of TB in South Africa, of which 94 000 were co-infected with HIV. Although TB treatments exist, poor patient compliance and drug resistance are challenges to TB management programs worldwide. Here, this challenge was addressed by the development of a polymeric anti-TB nanodrug delivery system for anti-TB drugs that could enable entry, targeting and sustained release for longer periods, hence reducing the dose frequency and simultaneously improve patient compliance. The aim was to prepare functionalised polymeric nano drug delivery vehicles to target TB infected macrophage cells. Successful nano encapsulation of anti-TB drugs was achieved and uptake of the antibiotics in the cells, demonstrated. A possible targeting agent, mycolic acids (MA) from M. tuberculosis was explored. The MA incorporated into nanoparticles could possibly serve as a ligand for cholesterol-rich areas, due to the cholesteroid nature of MA and the fact that MA is attracted to cholesterol. In another targeting scenario, MA incorporated into nanoparticles may interact with the anti-mycolic acid antibodies that are anticipated to be present in higher concentrations at the infected areas. The cholesteroid nature of MA was confirmed and how it related to the fine structure of the MA. The prepared MA containing nanoparticles were shown in vitro to be taken up in macrophage cell lines, without the MA hindering the uptake of the particles. In terms of toxicity, nanoparticles with or without MA were found to be acceptable for use, although MA did affect the viability of the cells more than poly, DL, lactic-coglycolic acid particles alone in in vitro studies. This paves the way for testing MA as a ligand to target anti-TB drugs to the sites of infection in human TB patients.Thesis (PhD)--University of Pretoria, 2010.Biochemistryunrestricte

Blood ketone bodies and breath acetone analysis and their correlations in type 2 diabetes mellitus

Analysis of volatile organic compounds in the breath for disease detection and monitoring has gained momentum and clinical significance due to its rapid test results and non-invasiveness, especially for diabetes mellitus (DM). Studies have suggested that breath gases, including acetone, may be related to simultaneous blood glucose (BG) and blood ketone levels in adults with types 2 and 1 diabetes. Detecting altered concentrations of ketones in the breath, blood and urine may be crucial for the diagnosis and monitoring of diabetes mellitus. This study assesses the e cacy of a simple breath test as a non-invasive means of diabetes monitoring in adults with type 2 diabetes mellitus. Human breath samples were collected in Tedlar bags and analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). The measurements were compared with capillary BG and blood ketone levels ( -hydroxybutyrate and acetoacetate) taken at the same time on a single visit to a routine hospital clinic in 30 subjects with type 2 diabetes and 28 control volunteers. Ketone bodies of diabetic subjects showed a significant increase when compared to the control subjects; however, the ketone levels were was controlled in both diabetic and non-diabetic volunteers. Worthy of note, a statistically significant relationship was found between breath acetone and blood acetoacetate (R = 0.89) and between breath acetone and -hydroxybutyrate (R = 0.82).Figure S1: Reconstructed GC-MS ion chromatograms (m/z 181) of patient breath samples without insulin injection (a), diabetic breath with insulin (b), and non-diabetic breath (c) sampled using on-fiber SPME derivatization with PFBHA. Figure S2: The measured breath acetone concentration by SPME GC/MS and versus blood glucose in diabetic patients.DSI-CSIRhttps://www.mdpi.com/journal/diagnosticsam2020BiochemistryGeneticsMicrobiology and Plant Patholog

Blood ketone bodies and breath acetone analysis and their correlations in type 2 diabetes mellitus

CITATION: Saasa, V., et al., 2019. Blood ketone bodies and breath acetone analysis and their correlations in type 2 diabetes mellitus. Diagnostics, 9(4). doi:10.3390/diagnostics9040224.The original publication is available at https://www.mdpi.com/journal/diagnosticsAnalysis of volatile organic compounds in the breath for disease detection and monitoring has gained momentum and clinical significance due to its rapid test results and non-invasiveness, especially for diabetes mellitus (DM). Studies have suggested that breath gases, including acetone, may be related to simultaneous blood glucose (BG) and blood ketone levels in adults with types 2 and 1 diabetes. Detecting altered concentrations of ketones in the breath, blood and urine may be crucial for the diagnosis and monitoring of diabetes mellitus. This study assesses the efficacy of a simple breath test as a non-invasive means of diabetes monitoring in adults with type 2 diabetes mellitus. Human breath samples were collected in Tedlar™ bags and analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). The measurements were compared with capillary BG and blood ketone levels (β-hydroxybutyrate and acetoacetate) taken at the same time on a single visit to a routine hospital clinic in 30 subjects with type 2 diabetes and 28 control volunteers. Ketone bodies of diabetic subjects showed a significant increase when compared to the control subjects; however, the ketone levels were was controlled in both diabetic and non-diabetic volunteers. Worthy of note, a statistically significant relationship was found between breath acetone and blood acetoacetate (R = 0.89) and between breath acetone and β-hydroxybutyrate (R = 0.82).DSI-CSIRhttps://www.mdpi.com/2075-4418/9/4/224#Publisher’s versio

The antigenicity and cholesteroid nature of mycolic acids determined by recombinant chicken antibodies

Mycolic acids (MA) are major, species-specific lipid components of Mycobacteria and related genera. In Mycobacterium tuberculosis, it is made up of alpha-, methoxy- and keto- MA, each with specific biological functions and conformational characteristics. Antibodies in tuberculosis (TB) patient sera respond differently towards the three MA classes and were reported to cross-react with cholesterol. To understand the antigenicity and cholesterol cross-reactivity of MA, we generated three different chicken -derived phage-displayed single- chain variable fragments (scFv) that reacted similarly towards the natural mixture of MA, but the first recognized all three classes of chemically synthetic MAs, the second only the two oxygenated types of MAs and the third only methoxy MA. The cholesterol cross-reactivity was investigated after grafting each of the three scFv types onto two configurations of constant chain domains±CH1-4 and CH2-4. Weak but significant cross-reactivity with cholesterol was found only with CH2-4 versions, notably those two that were also able to recognize the trans-keto MA. The cholesteroid nature of mycobacterial mycolic acids therefore seems to be determined by the trans-keto MA subclass. The significantly weaker binding to cholesterol in comparison to MA confirms the potential TB diagnostic application of these antibodies.S1 Fig. Sequences of gallibody clones produced by antibody engineering. 12) Anti-MA 12, 16) Anti-MA 16, 18) Anti-MA 18, CH1-4 = full length constant region, CH2-4 = truncated constant region, VH = variable heavy chain, VL = variable light chain.S2 Fig. SDS-PAGE analysis illustrating gallibody purification using Ni-NTA affinity columns. A) 12CH1-4, B) 16CH1-4, C) 18CH1-4, D) 12CH2-4, E) 16CH2-4, F) 18CH2-4. Gel lanes 1) Marker, 2) Culture supernatant, 3) Flow through 1, 4) Flow through 2, 5) Washes, 6) Elution 1, 7) Elution 2, 8) Elution 3, 9) Elution 4. Successful purification is demonstrated by the comparable thickness of the 67 kDa band obtained with the culture supernatant (2) and the elutions (6±9).S1 Dataset. Experimental data used for producing Figs 3 and 4.S2 Dataset. Experimental data used for producing Fig 5.S3 Dataset. Experimental data used for producing Fig 6.The Council for Scientific and Industrial Research (CSIR) parliamentary grants (YL) and the National Research Foundation of South Africa for the grants, unique grant numbers: 99386 (HR), 88622, 80577 (YL) and TTK1206281756 (LN).http://www.plosone.orgam2018Biochemistr

Effect of varying ethanol and water compositions on the acetone sensing properties of WO3 for application in diabetes mellitus monitoring

Tungsten oxide based gas sensors have attracted a lot of attention in breath acetone analysis due to their potential in clinical diagnosis of diabetes. The major problem with this material in sensor application has been remarkable response to all gases but low selectivity to specific gases. Herein, we report the gas sensing performance ofWO3 materials which were synthesized by varying water and ethanol ratios using a facile solvothermal method for acetone detection. The gas sensing properties of as-preparedWO3 were tested on acetoneC7H8,NO2, NH3,H2S andCH4 under relative humidity. X-ray diffraction patterns show that as-preparedWO3 samples are mainly composed of monoclinic WO3, a phase having relatively high selectivity to acetone. The as-preparedWO3 sensors produced using 51:49 ratio of water: ethanol show an increase in acetone response as the acetone concentration increases and a decrease in acetone response as the relative humidity increases. The sensor responded to a very low acetone concentration ranging from 0.5 to 4.5 ppm which is normally found in human breath. Furthermore, the sensor exhibited high sensitivity and selectivity to low ppm of acetone at 100 °C. On contrary, the sensor showed significantly lower response to other gases tested.CSIR-DSThttp://iopscience.iop.org/journal/2053-1591am2021BiochemistryGeneticsMicrobiology and Plant Patholog

Synthesis and characterisation of quantum dots coupled to mycolic acids as a water-soluble fluorescent probe for potential lateral flow detection of antibodies and diagnosis of tuberculosis

This work explores the potential use of cadmium-based quantum dots (QDs) coupled to mycolic acids (MAs) as a fluorescent probe to detect anti-MA antibodies which are biomarkers for tuberculosis (TB). The use of free MAs as antigens for the serodiagnosis of TB is known but has not been developed into a point of care test. This study focuses on the synthesis, solubility, and lateral flow of QDs coupled to MAs. Water-soluble CdSe/ZnS QDs capped with l-cysteine were synthesised and covalently coupled to MAs via amide linkages to form a water-soluble fluorescent probe: MA-CdSe/ZnS QDs. The MA-CdSe/ZnS QDs showed broad absorption bands and coupling, confirmed by the presence of amide bonds in the Fourier-transform infrared (FTIR) spectrum, resulting in a blue shift in fluorescence. Powder X-ray diffraction (XRD) revealed a shift and increase in the number of peaks for MA-CdSe/ZnS QDs relative to the L-cys-CdSe/ZnS QDs, suggesting that coupling changed the crystal structure. The average particle size of MA-CdSe/ZnS QDs was ~3.0 nm. Visual paper-based lateral flow of MA-CdSe/ZnS QDs was achieved on strips of nitrocellulose membrane with both water and membrane blocking solution eluents. The highly fluorescent MA-CdSe/ZnS QDs showed good water solubility and lateral flow, which are important properties for fluorescence sensing applications.TWAS-NRF doctoral scholarship funding and a University of Pretoria postgraduate student bursary.http://wileyonlinelibrary.com/journal/bio2022-11-23hj2021Chemistr

In vivo evaluation of the biodistribution and safety of PLGA nanoparticles as drug delivery systems

The remarkable physicochemical properties of particles in the nanometer range have been proven to address many challenges in the field of science. However, the possible toxic effects of these particles have raised some concerns. The aim of this article is to evaluate the effects of poly(lactide-co-glycolide) (PLGA) nanoparticles in vitro and in vivo compared to industrial nanoparticles of a similar size range such as zinc oxide, ferrous oxide, and fumed silica. An in vitro cytotoxicity study was conducted to assess the cell viability following exposure to PLGA nanoparticles. Viability was determined by means of a WST assay, wherein cell viability of greater than 75% was observed for both PLGA and amorphous fumed silica particles and ferrous oxide, but was significantly reduced for zinc oxide particles. In vivo toxicity assays were performed via histopathological evaluation, and no specific anatomical pathological changes or tissue damage was observed in the tissues of Balb/C mice. The extent of tissue distribution and retention following oral administration of PLGA particles was analyzed for 7 days. After 7 days, the particles remained detectable in the brain, heart, kidney, liver, lungs, and spleen. The results show that a mean percentage (40.04%) of the particles were localized in the liver, 25.97% in the kidney, and 12.86% in the brain. The lowest percentage was observed in the spleen. Thus, based on these assays, it can be concluded that the toxic effects observed with various industrial nanoparticles will not be observed with particles made of synthetic polymers such as PLGA when applied in the field of nanomedicine. Furthermore, the biodistribution of the particles warrants surface modification of the particles to avoid higher particle localization in the liver

State of the art and future directions in nanomedicine for tuberculosis.

Research Article published by Expert Opinion on Drug Delivery Volume 10, Issue 1220 -13Introduction: Tuberculosis (TB) ranks the second leading cause of death from an infectious disease worldwide. However, treatment of TB is affected by poor patient compliance due to the requirement for daily drug administration, for lengthy periods of time, often with severe drug-induced side effects. Nanomedicines have the potential to improve treatment outcomes by providing therapies with reduced drug doses, administered less frequently, under shortened treatment durations. Areas covered: In this article, we present the pathophysiology of the disease, focusing on pulmonary TB and the characteristics of drugs used in treatment and discuss the application of nanomedicines within this scope. We also discuss new formulation approaches for TB nanomedicines and directions for future research. Expert opinion: Nanomedicines have the potential to improve TB treatment outcomes. New approaches such as nanoparticle systems able to impact the immune response of macrophages and deliver drug intracellularly, as well as the use of polymer–drug conjugates for drug delivery, are likely to play an important role in TB nanomedicines in future. However, further research is required before TB nanomedicines can be translated to the clinic

Polylactide-based Magnetic Spheres as Efficient Carriers for Anticancer Drug Delivery

To improve traditional cancer therapies, we synthesized polylactide (PLA) spheres coencapsulating magnetic nanoparticles (MNPs, Fe₃O₄) and an anticancer drug (doxorubicin, DOX). The synthesis process involves the preparation of Fe₃O₄ NPs by a coprecipitation method and then PLA/DOX/Fe₃O₄ spheres using the solvent evaporation (oil-in-water) technique. The Fe₃O₄ NPs were coated with oleic acid to improve their hydrophobicity and biocompatibility for medical applications. The structure, morphology and properties of the MNPs and PLA/DOX/Fe₃O₄ spheres were studied using various techniques, such as FTIR, SEM, TEM, TGA, VSM, UV–vis spectroscopy, and zeta potential measurements. The in vitro DOX release from the spheres was prolonged, sustained, and pH-dependent and fit a zero-order kinetics model and an anomalous mechanism. Interestingly, the spheres did not show a DOX burst effect, ensuring the minimal exposure of the healthy cells and an increased drug payload at the tumor site. The pronounced biocompatibility of the PLA/DOX/Fe₃O₄ spheres with HeLa cells was proven by a WST assay. In summary, the synthesized PLA/DOX/Fe₃O₄ spheres have the potential for magnetic targeting of tumor cells to transform conventional methods

Preclinical assessment of 68Ga‐PSMA‐617 entrapped in a microemulsion delivery system for applications in prostate cancer PET/CT imaging

Please read abstract in the article.NTeMBI, Grant/Award Number: N/A; Carl and Emily Fuchs Foundationhttp://wileyonlinelibrary.com/journal/jlcr2020-06-15hj2020Nuclear Medicin