Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 11Citation - Scopus: 12Colorimetric and Fluorometric Profiling of Advanced Glycation End Products(American Chemical Society, 2022) Ammanath, Gopal; Karabacak, Soner; Karabacak, Soner; Yıldız, Ümit Hakan; Boehm, Bernhard O.; Yıldız, Ümit Hakan; Alagappan, Palaniappan; Liedberg, Bo; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyProfiling of advanced glycation end products (AGEs) is an emerging area of clinical significance for disease diagnosis and prognosis. Typically, concentrations of AGEs are estimated in laboratories by trained personnel using sophisticated equipment. Herein, a facile approach for colorimetric and fluorometric profiling of AGEs is reported for rapid and on-site analysis. The concentrations of AGE levels in plasma are estimated via changes in optical properties of polythiophenes (PTs) upon interaction with aptamers (Apts) in the presence and in the absence of AGEs. To validate the proposed approach, glyceraldehyde-derived AGEs (AGE class 1 [AGE1]), the biomarker associated with cardiovascular diseases and diabetes, are used as a model system. Colorimetric analysis yielded linear responses for AGE1 for clinically relevant concentration ranges between 1.5 and 300 μg/mL with a limit of detection (LOD) of ∼1.3 μg/mL. Subsequently, an approach utilizing PTs with four different pendant groups in conjunction with four different Apts is demonstrated for qualitative colorimetric profiling and for quantitative fluorometric profiling of up to four AGEs in clinical matrices. Principal component analysis (PCA) of fluorometric responses of AGE-spiked samples yielded distinct responses for the different AGEs tested. Thus, the proposed approach ascertains rapid profiling of spiked AGEs in plasma samples without the requirement of preanalytical processing and advanced instrumentation, thereby facilitating on-site diagnosis.Article Citation - WoS: 40Citation - Scopus: 41Colorimetric Urinalysis for On-Site Detection of Metabolic Biomarkers(American Chemical Society, 2020) Yeasmin, Sanjida; Yıldız, Ümit Hakan; Ammanath, Gopal; Ali, Yusuf; Boehm, Bernhard O.; Yıldız, Ümit Hakan; Palaniappan, Alagappan; Liedberg, Bo; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyOver the past few decades, colorimetric assays have been developed for cost-effective and rapid on-site urinalysis. Most of these assays were employed for detection of biomarkers such as glucose, uric acid, ions, and albumin that are abundant in urine at micromolar to millimolar levels. In contrast, direct assaying of urinary biomarkers such as glycated proteins, low-molecular-weight reactive oxygen species, and nucleic acids that are present at significantly lower levels (nanomolar to picomolar) remain challenging due to the interferences from the urine sample matrix. State-of-the-art assays for detection of trace amounts of urinary biomarkers typically utilize time-consuming and equipment-dependent sample pretreatment or clean-up protocols prior to assaying, which limits their applicability for on-site analysis. Herein, we report a colorimetric assay for on-site detection of trace amount of generic biomarkers in urine without involving tedious sample pretreatment protocols. The detection strategy is based on monitoring the changes in optical properties of poly(3-(4-methyl-3'-thienyloxy)propyltriethylammonium bromide) upon interacting with an aptamer or a peptide nucleic acid in the presence and absence of target biomarkers of relevance for the diagnosis of metabolic complications and diabetes. As a proof of concept, this study demonstrates facile assaying of advanced glycation end products, 8-hydroxy-2'-deoxyguanosine and hepatitis B virus DNA in urine samples at clinically relevant concentrations, with limits of detection of similar to 850 pM, similar to 650 pM, and similar to 1 nM, respectively. These analytes represent three distinct classes of biomarkers: (i) glycated proteins, (ii) low-molecular-weight reactive oxygen species, and (iii) nucleic acids. Hence, the proposed methodology is applicable for rapid detection of generic biomarkers in urine, without involving sophisticated equipment and skilled personnel, thereby enabling on-site urinalysis. At the end of the contribution, we discuss the opportunity to translate the homogeneous assay into a paper-based format.Article Citation - WoS: 32Citation - Scopus: 32Luminescent Device for the Detection of Oxidative Stress Biomarkers in Artificial Urine(American Chemical Society, 2018) Ammanath, Gopal; Yıldız, Ümit Hakan; Palaniappan, Alagappan; Liedberg, Bo; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyA luminescent paper-based device for the visual detection of oxidative stress biomarkers is reported. The device consists of a polyvinylidene fluoride membrane impregnated with poly(3-alkoxy-4-methylthiophene) (PT) for colorimetric detection. 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker associated with oxidative stress, is used as a model system for validating the proposed methodology. The detection strategy is based on monitoring the changes in optical properties of PT associated with its conformational changes upon interaction with an aptamer in the presence and in the absence of 8-OHdG. Fluorometric and colorimetric monitoring revealed linear responses for 8-OHdG concentrations between 50 pM and 500 nM (∼14 pg/mL to 140 ng/mL), with limits of detection of ∼300 pM and ∼350 pM, respectively for (n = 3). Colorimetric responses in artificial urine ascertained rapid, sensitive, and selective detection of 8-OHdG at clinically relevant (pM to nM) concentration levels. Furthermore, the proposed methodology enables point-of-care diagnostics for oxidative stress without requiring sophisticated instrumentation.Article Citation - WoS: 24Citation - Scopus: 23Tailoring Conformation-Induced Chromism of Polythiophene Copolymers for Nucleic Acid Assay at Resource Limited Settings(American Chemical Society, 2016) Rajwar, Deepa; Yıldız, Ümit Hakan; Cheema, Jamal Ahmed; Palaniappan, Alagappan; Yıldız, Ümit Hakan; Liedberg, Bo; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyHere we report on the design and synthesis of cationic water-soluble thiophene copolymers as reporters for colorimetric detection of microRNA (miRNA) in human plasma. Poly(3-alkoxythiophene) (PT) polyelectrolytes with controlled ratios of pendant groups such as triethylamine/1-methyl imidazole were synthesized for optimizing interaction with target miRNA sequence (Tseq). Incorporation of specific peptide nucleic acid (PNA) sequences with the cationic polythiophenes yielded distinguishable responses upon formation of fluorescent PT-PNA-Tseq triplex and weakly fluorescent PT-Tseq duplex, thereby enabling selective detection of target miRNA. Unlike homopolymers of PT (hPT), experimental results indicate the possibility of utilizing copolymers of PT (cPT) with appropriate ratios of pendant groups for miRNA assay in complex matrices such as plasma. As an illustration, colorimetric responses were obtained for lung cancer associated miRNA sequence (mir21) in human plasma, with a detection limit of 10 nM, illustrating the feasibility of proposed methodology for clinical applications without involving sophisticated instrumentation. The described methodology therefore possesses high potential for low-cost nucleic acid assays in resource-limited settings.