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      Fabrication of Zinc Protoporphyrin-Modified Gold Electrode for Sensitive and Fast Detection of Vascular Endothelial Growth Factor

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      Chemosensors

      MDPI AG

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          Abstract

          Vascular endothelial growth factor (VEGF) is directly related to cancer growth and its distant spread, and thus, it is considered a promising biomarker for diagnosis and post-treatment monitoring of patients with malignancies. Zinc protoporphyrin (ZnPP) is a zinc-centered raw purple compound (protoporphyrin) that has unique optical and electrochemical characteristics. In this study, we used a ZnPP-modified gold electrode to generate a chemical bond with Avastin by self-assembly and fabricate a Au/ZnPP/Avastin electrode. Bovine serum protein (BSA) was added to the electrode to prevent non-specific linkage with biomolecules. The prepared Au/ZnPP/Avastin/BSA electrodes were used for the detection of VEGF by cyclic voltammetry and amperometry. The optical properties of ZnPP were analyzed with an ultraviolet/visible/near-infrared spectrometer and a photoluminescence spectrometer. The structural and hydrophilic/hydrophobic properties of the ZnPP-modified gold electrodes were investigated by Fourier-transform infrared spectroscopy and contact angle gauge, respectively. VEGF was detected with the Au/ZnPP/Avastin/BSA electrodes prepared either with (w/LT) or without light treatment (w/o LT). The w/LT electrode showed a linear range and a sensitivity of 0.1 pg/mL–10 ng/mL and 6.52 μA/log(pg/mL)-cm2, respectively; the corresponding values for the w/o LT electrode were 10 pg/mL–10 ng/mL and 3.15 μA/log(pg/mL)-cm2, respectively. The w/LT electrode had good specificity for VEGF and was minimally influenced by other molecules. The excellent detection range, high sensitivity, and high selectivity for VEGF detection indicate that Au/ZnPP/Avastin electrodes have great potential for diagnostic and prognostic applications in patients with malignancies.

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          Most cited references 36

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          Bevacizumab (Avastin), a humanized anti-VEGF monoclonal antibody for cancer therapy.

          Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in vivo. The tyrosine kinases Flt-1 (VEGFR-1) and Flk-1/KDR (VEGFR-2) are high affinity VEGF receptors. VEGF plays an essential role in developmental angiogenesis and is important also for reproductive and bone angiogenesis. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. Anti-VEGF monoclonal antibodies and other VEGF inhibitors block the growth of several tumor cell lines in nude mice. Clinical trials with VEGF inhibitors in a variety of malignancies are ongoing. Recently, a humanized anti-VEGF monoclonal antibody (bevacizumab; Avastin) has been approved by the FDA as a first-line treatment for metastatic colorectal cancer in combination with chemotherapy. Furthermore, VEGF is implicated in intraocular neovascularization associated with diabetic retinopathy and age-related macular degeneration.
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            Mechanism of dye response and interference in the Bradford protein assay.

            Bradford Coomassie brilliant blue G-250 protein-binding dye exists in three forms: cationic, neutral, and anionic. Although the anion is not freely present at the dye reagent pH, it is this form that complexes with protein. Dye binding requires a macromolecular form with certain reactive functional groups. Interactions are chiefly with arginine rather than primary amino groups; the other basic (His, Lys) and aromatic residues (Try, Tyr, and Phe) give slight responses. The binding behavior is attributed to Van der Waals forces and hydrophobic interactions. Assay interference by bases, detergents, and other compounds are explained in terms of their effects upon the equilibria between the three dye forms.
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              Intravitreal bevacizumab (Avastin) for persistent new vessels in diabetic retinopathy (IBEPE study).

              To evaluate the short-term fluorescein angiographic and visual acuity effects of a single intravitreal injection of bevacizumab (Avastin) for the management of persistent new vessels (NV) associated with diabetic retinopathy. A prospective, nonrandomized open-label study of diabetic patients with actively leaking NV refractory to laser treatment and best-corrected Early Treatment Diabetic Retinopathy Study visual acuity (BCVA) worse than 20/40. Standardized ophthalmic evaluation was performed at baseline and at weeks 1, 6, and 12 (+/-1) following intravitreal injection of 1.5 mg of bevacizumab. Main outcome measures include changes in total area of fluorescein leakage from active NV and BCVA. Fifteen consecutive patients (men, 9 [60%]; women, 6 [40%]) were included and all completed the 12-week follow-up period of the study. The mean +/- SD age of participants was 60.08 +/- 7.75 years (median, 59.5; range, 49-73 years). At baseline, mean +/- standard error of the mean (SEM) NV leakage area was 27.79 +/- 6.29 mm2. The mean +/- SEM area of active leaking NV decreased significantly to 5.43 +/- 2.18 mm2 and 5.50 +/- 1.24 mm2 (P < 0.05, Tukey multiple comparisons post-test) at 1 and 12 weeks postinjection, respectively; at week 6 no leakage was observed. The mean +/- SEM logMAR (Snellen equivalent) BCVA improved significantly from 0.90 (20/160) +/- 0.11 at baseline to 0.76 (20/125(+2)) +/- 0.12, 0.77 (20/125(+2)) +/- 0.11, and 0.77 (20/125(+2)) +/- 0.12 at weeks 1, 6, and 12, respectively (P < 0.05, Tukey multiple comparisons post-test). No major adverse events were observed. Intravitreal injection of bevacizumab achieved short-term reduction of fluorescein leakage from persistent active NV without loss of vision in patients with diabetic retinopathy. Further studies to investigate the role of anti-VEGF therapy with bevacizumab for the management of diabetic retinopathy refractory to laser treatment are warranted.
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                Author and article information

                Journal
                CHEMO9
                Chemosensors
                Chemosensors
                MDPI AG
                2227-9040
                February 2021
                January 23 2021
                : 9
                : 2
                : 21
                Article
                10.3390/chemosensors9020021
                © 2021
                Product
                Self URI (article page): https://www.mdpi.com/2227-9040/9/2/21

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