iRGD-Guided Silica/Gold Nanoparticles for Efficient Tumor-Targeting and Enhancing Antitumor Efficacy Against Breast Cancer

Background

Breast cancer presents significant challenges due to the limited effectiveness of available treatments and the high likelihood of recurrence. iRGD possesses both RGD sequence and C-terminal sequence and has dual functions of targeting and membrane penetration. iRGD-modified nanocarriers can enhance drug targeting of tumor vascular endothelial cells and penetration of new microvessels, increasing drug concentration in tumor tissues.

Methods

The amidation reaction was carried out between SiO2/AuNCs and iRGD/PTX, yielding a conjugated drug delivery system (SiO2/AuNCs-iRGD/PTX, SAIP@NPs). The assessment encompassed the characterization of the morphology, particle size distribution, physicochemical properties, in vitro release profile, cytotoxicity, and cellular uptake of SAIP@NPs. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed using a small animal in vivo imaging system and a tumor-bearing nude mice model, respectively. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed utilizing a small animal in vivo imaging system and an in situ nude mice breast cancer xenograft model, respectively.

Results

The prepared SAIP@NPs exhibited decent stability and a certain slow-release effect in phosphate buffer (PBS, pH 7.4). In vitro studies had shown that, due to the dual functions of transmembrane and targeting of iRGD peptide, SAIP@NPs exhibited strong binding to integrin αvβ3, which was highly expressed on the membrane of MDA-MB-231 cells, improving the uptake capacity of tumor cells, inhibiting the rapid growth of tumor cells, and promoting tumor cell apoptosis. The results of animal experiments further proved that SAIP@NPs had longer residence time in tumor sites, stronger anti-tumor effect, and no obvious toxicity to major organs of experimental animals.

Conclusion

The engineered SAIP@NPs exhibited superior functionalities including efficient membrane permeability, precise tumor targeting, and imaging, thereby significantly augmenting the therapeutic efficacy against breast cancer with a favorable safety profile.

Unique Electron-Transfer-Mediated Electrochemiluminescence of AuPt Bimetallic Nanoclusters and the Application in Cancer Immunoassay

Noble Metal nanoclusters (NCs) are promising electrochemiluminescence (ECL) emitters due to their amazing optical properties and excellent biocompatibility. They have been widely used in the detection of ions, pollutant molecules, biomolecules, etc. Herein, we found that glutathione-capped AuPt bimetallic NCs (GSH-AuPt NCs) emitted strong anodic ECL signals with triethylamine as co-reactants which had no fluorescence (FL) response. Due to the synergistic effect of bimetallic structures, the ECL signals of AuPt NCs were 6.8 and 94 times higher than those of monometallic Au and Pt NCs, respectively. The electric and optical properties of GSH-AuPt NCs differed from those of Au and Pt NCs completely. An electron-transfer mediated ECL mechanism was proposed. The excited electrons may be neutralized by Pt(II) in GSH-Pt and GSH-AuPt NCs, resulting in the vanished FL. Furthermore, abundant TEA radicals formed on the anode contributed electrons to the highest unoccupied molecular orbital of GSH-Au_2.5Pt NCs and Pt(II), booming intense ECL signals. Because of the ligand effect and ensemble effect, bimetallic AuPt NCs exhibited much stronger ECL than GSH-Au NCs. A sandwich-type immunoassay for alpha fetoprotein (AFP) cancer biomarkers was fabricated with GSH-AuPt NCs as signal tags, which displayed a wide linear range from 0.01 to 1000 ng·mL^-1 and a limit of detection (LOD) down to 1.0 pg·mL^-1 at 3S/N. Compared to previous ECL AFP immunoassays, this method not only had a wider linear range but also a lower LOD. The recoveries of AFP in human serum were around 108%, providing a wonderful strategy for fast, sensitive, and accurate cancer diagnosis.

Fluorescence immunosensor based on functional nanomaterials and its application in tumor biomarker detection

An immunosensor is defined as an analytical device that detects the binding of an antigen to its specific antibody by coupling an immunochemical reaction to the surface of a device called a transducer. Fluorescence immunosensing is one of the most promising immunoassays at present, and has the advantages of simple operation, fast response and high stability. A traditional fluorescence immunosensor often uses an enzyme-labelled antibody as a recognition unit and an organic dye as a fluorescence probe, so it is easily affected by environmental factors with low sensitivity. Nanomaterials have unique photostability, catalytic properties and biocompatibility, which open up a new path for the construction of stable and sensitive fluorescence immunosensors. This paper briefly introduces different kinds of immunosensors and the role of nanomaterials in the construction of immunosensors. The significance of fluorescent immunosensors constructed from functional nanomaterials to detect tumor biomarkers was analyzed, and the strategies to further improve the performance of fluorescent immunosensors and their future development trend were summarized.

A Sensitive Fluorescent Immunoassay for Prostate Specific Antigen Detection Based on Signal Amplify Strategy of Horseradish Peroxidase and Silicon Dioxide Nanospheres

A simple, sensitive, and fluorescent immunoassay for the detection of prostate-specific antigen (PSA) based on horseradish peroxidase and silicon dioxide nanospheres as a signal amplification strategy has been described. In the design, the primary antibody (Ab₁) of PSA was first immobilized on the 96-well plates via physical adsorption between polystyrene and hydrophobic groups of the antibody molecule. The silicon dioxide nanospheres (SiO₂ NSs), with large surface area and good biocompatibility, were loaded with horseradish peroxidase (HRP) and horseradish peroxidase-labeled secondary antibodies (HRP-Ab₂) as signal amplification systems. In the presence of PSA, a sandwich-type immunocomplex composed of Ab₁-Ag-HRP-Ab₂ had been formed. Fluorescence technology was employed to obtain the response signal of the immunoassay in the L-tyrosine and H₂O₂ systems. Experiment results showed that a strong and stable fluorescent signal at 416 nm (excitation wavelength: 325 nm) was observed, and the changes in fluorescent intensity were related to the levels of PSA. Under the optimal conditions, the relative fluorescence intensity was linear with the logarithm of PSA concentration from 0.03 to 100 ng·mL^-1, with a detection limit of 0.01 ng·mL^-1 (at a signal/noise ratio of 3). In contrast to other fluorescent immunoassays, the sandwich-type immunoreaction based on the high binding ELISA plates has the advantages of being simple, stable, and easy to operate, high selectivity, small sample quantity, etc., which can be widely used in the selective detection of a variety of targets, from DNA to proteins and small molecules. Such fluorescent immunoassays should be feasible for the fields of molecular diagnosis and other life science fields in the future.

Quantitative and simultaneous detection of two inflammation biomarkers via a fluorescent lateral flow immunoassay using dual-color SiO2@QD nanotags

An on-site detection strategy is reported based on dual-color SiO₂@quantum dot (QD)-integrated lateral flow immunoassay (LFA) strip to realize the quantitative and simultaneous detection of C-reactive protein (CRP) and procalcitonin (PCT) in serum. The dual-color SiO₂@QD nanotags with monodispersity and excellent luminescence were synthesized using polyethyleneimine-mediated electrostatic adsorption of dense red CdSe/ZnS-COOH (excitation/emission 365/625 nm) or green CdSe/ZnS-COOH (excitation/emission 365/525 nm) QDs on the surface of 180 nm SiO₂ spheres and were conjugated with anti-PCT and anti-CRP monoclonal antibodies, as stable and fluorescent-enhanced QD nanotags in the LFA system. The use of SiO₂@QDs with two different fluorescent signals caused the sensitivity and specificity of the multiplex LFA system. As a result, the proposed assay provided a wide logarithmic determination range with a CRP quantitative range of 0.5-10³ ng/mL and PCT quantitative range of 0.05-10³ ng/mL. The limits of detection (LODs) of CRP and PCT reached 0.5 and 0.05 ng/mL, respectively. The SiO₂@QD-based LFA showed great potential as rapid detection tool for the simultaneous monitoring of CRP and PCT in serum sample.

Immunoglobulin G-Encapsulated Gold Nanoclusters as Fluorescent Tags for Dot-Blot Immunoassays

Few-atom gold nanoclusters (AuNCs) have been fabricated and used for various fields owing to their remarkable optical and photophysical features. However, the rational design for the antibody-mediated synthesis of fluorescent AuNCs for direct antigen-antibody reactions remains unexplored. In this work, immunoglobulin G (IgG)-functionalized AuNCs (IgG-AuNCs) were successfully prepared via a facile and fast biomineralization process. The generated IgG-AuNCs can emit intense red fluorescence with a high photoluminescence quantum yield. Besides strong emission, the bioactivity of IgG on the IgG-AuNCs can be retained. Surface plasmon resonance measurements suggested that IgG-AuNCs can bind to goat anti-human IgG with an affinity constant of 6.21 × 10^-8 M. A simple detection method was then developed using a dot-blot immunoassay with IgG-AuNCs as fluorescent tags. Experimental results confirmed that the IgG-AuNC-based fluorescent reporters had many advantages such as low nonspecific adsorption and good photostability, offering immense potential for the development of efficient biosensors. This work can be extended to other specific antibodies to produce multifunctional AuNCs and utilized to detect and monitor targeted analytes and biological events of interest.

Ursolic acid a promising candidate in the therapeutics of breast cancer: Current status and future implications

Breast cancer [BC] is the deadliest neoplasm in women globally and the second leading cause of cancer associated deaths. Current treatment methods include chemotherapy, hormonal therapy, radiation therapy and surgery. However, BC has shown resistance to these therapies and are often associated with side effects, multidrug resistance, recurrence are the major issues in BC treatment. Currently, dietary phytocompounds have emerged as beneficial agents for the prevention and treatment of cancer because of their safe and cost effective nature. Ursolic acid [UA] is widely spread in fruits and vegetables having the ability to inhibit BC proliferation, angiogenesis and metastasis, arrest cell cycle, induced apoptosis, scavenge free radicals and regulate several anti-apoptotic and pro-apoptotic proteins. UA has also shown potential anticancer, anti-inflammatory and antioxidant activities in several human BC cells. This review paper encompasses the role of UA against BC and their mechanism of action in vitro and in vivo studies.

Early Diagnosis of Breast Cancer

Early-stage cancer detection could reduce breast cancer death rates significantly in the long-term. The most critical point for best prognosis is to identify early-stage cancer cells. Investigators have studied many breast diagnostic approaches, including mammography, magnetic resonance imaging, ultrasound, computerized tomography, positron emission tomography and biopsy. However, these techniques have some limitations such as being expensive, time consuming and not suitable for young women. Developing a high-sensitive and rapid early-stage breast cancer diagnostic method is urgent. In recent years, investigators have paid their attention in the development of biosensors to detect breast cancer using different biomarkers. Apart from biosensors and biomarkers, microwave imaging techniques have also been intensely studied as a promising diagnostic tool for rapid and cost-effective early-stage breast cancer detection. This paper aims to provide an overview on recent important achievements in breast screening methods (particularly on microwave imaging) and breast biomarkers along with biosensors for rapidly diagnosing breast cancer.