Single Gold Nanoparticles Counter: An Ultrasensitive Detection Platform for One-Step Homogeneous Immunoassays and DNA Hybridization Assays

Abstract

Synthesis of gold nanoparticles (GNPs).GNPs were synthesized by reduction of the HAuCl 4 solution with sodium citrate. 1 Briefly, 100 mL of 0.01% (w/v) of the HAuCl 4 solution was heated to boiling for 15 minutes, and then 1% (w/v) sodium citrate solution was added. The volume added depended on the requirement size of GNPs, and 1 mL of sodium citrate solution was needed for 36 nm GNPs. Heating continued for 15 minutes after the solution color remained unchanged. After cooling down to room temperature, the prepared GNPs stock solution was stored at 4 o C for further use. The concentration of GNPs was calculated according to the reference. 2 GNPs were further purified and concentrated by centrifugation (Beckman Coulter, USA) 2 times at 2,500 rpm for 30 min (washing buffer: 0.01 M PBS, pH 7.4) prior to further use. ELISA method (contrast experiments).To investigate the reliability of our method, the human sera were analyzed with ELISA method according to the operational manuals of ELISA kits. Briefly, 50 μL antigen or human serum samples were added to the wells of the ELISA plate, and incubated at 37 o C for

Multifunctional Oval-Shaped Gold-Nanoparticle-Based Selective Detection of Breast Cancer Cells Using Simple Colorimetric and Highly Sensitive Two-Photon Scattering Assay

“…Cancer has been described in early medical texts from antiquity, but until now, it remains the second leading cause of death in our world. − Breast cancer is the most common cancer among women, and it is the second leading cause of cancer deaths in women today, after lung cancer. − Rapid selective detection of cancer cells is an important challenge for the diagnosis and treatment of tumors. − The key to the effective and ultimately successful treatment of diseases such as cancer is an early and accurate diagnosis. With oncogenes, such as human epidermal growth factor receptor 2 (HER2)/Neu, overexpression is found in about 30% of different breast cancer cases and 20% of ovarian cancer cases. − Also, there is mounting evidence for the role of HER2 overexpression in patients with gastric cancer. − As a result, immunophenotypic analysis of cancer cells using antibody probes for specific surface antigens has limitations due to the fact that antigens used for cell recognition are normally not exclusively expressed on any single cell type, dramatically influencing selectivity and resulting in false positive signals. ,, Target cell-specific aptamers have the potential to serve as molecular probes for specific recognition of the cancerous cells from complex mixtures including whole blood samples. ,,,, Most aptamers reported for breast cancer cell lines have weak binding affinity and thus low signal in molecular imaging, limiting their ability for highly sensitive detection of cancer cells. …”

“…With oncogenes, such as human epidermal growth factor receptor 2 (HER2)/Neu, overexpression is found in about 30% of different breast cancer cases and 20% of ovarian cancer cases. − Also, there is mounting evidence for the role of HER2 overexpression in patients with gastric cancer. − As a result, immunophenotypic analysis of cancer cells using antibody probes for specific surface antigens has limitations due to the fact that antigens used for cell recognition are normally not exclusively expressed on any single cell type, dramatically influencing selectivity and resulting in false positive signals. ,, Target cell-specific aptamers have the potential to serve as molecular probes for specific recognition of the cancerous cells from complex mixtures including whole blood samples. ,,,, Most aptamers reported for breast cancer cell lines have weak binding affinity and thus low signal in molecular imaging, limiting their ability for highly sensitive detection of cancer cells. ,, In addition, during the early stages of cancer development, cancer cells will have a very low density of target membrane proteins for recognition of a specific cancer cell. In this case, single aptamer/antibody binding will not be enough to detect early stage cancer development. − Given the complexity and diversity of cancers, in order to increase sensitivity and selectivity, multivalent binding is usually considered to be essential for early stage disease diagnostics.…”

“…Due to the unique optical properties of nanomaterials, over the last 5 years, several groups have been developing suitable nanomaterials for cancer imaging and therapy. − In noble metal gold nanoparticles, the coherent collective oscillation of electrons in the conduction band induces large surface electric fields, which greatly enhances the radiative properties of these nanoparticles. − As a result, the light scattering cross section of metal nanoparticles is several orders of magnitude more intense than that of organic dyes, which makes it an excellent candidate for sensor development and novel contrast agents for optical detection. − …”

Preparation, Functionalization, Modification, and Applications of Nanostructured Gold: A Critical Review

“…For instant, Ren and colleagues have advanced an extremely careful and sensitive similar immune assay and DNA hybridization assay using plasmon scattering of single Au NP evaluation. The sandwich immuneo assay was employed to notice cancer biomarkers for example CEA, AFP in femtomolar range and aptamer recognition for thrombin as low as 2.72 pM [498]. Recently, Ling et al described an LSPR light scattering sensor for Ag + with unmodified Au NPs using the specific respect characteristic of Ag + with a cytosine-cytosine gap base pair.…”

Dna功能化金纳米及其应用

“…再次, 通过靶标存在时 AuNP@DNA 相互靠近, 使溶液吸收 峰 位 置 红 移 的 检 测 方 法 可 用 于 目 标 DNA [193] 或 mRNA [194] 的检测. 此外, 通过其他技术如散射光检 测(图 9(D)) [191,195] 、表面等离子体共振 [196] 、纳米颗粒 计数 [197] 、金种子生长 [198] 和电感耦合等离子体-质谱 联 合 [199] 等 技 术 的 偶 联 , 能 进 一 步 提 高 靶 标 诱 导 [41] 首先制备了两种不同的 AuNP@DNA, 然后利用互补 DNA 将两种 AuNP@ DNA 自组装成无定形的宏观材料(图 10(A)). 这种利 用 DNA 互补配对作用进行自组装的过程能够通过温 度的改变进行可逆调控.…”