Highly sensitive electrochemical detection of cholesterol based on Au-Pt NPs/PAMAM-ZIF-67 nanomaterials.

A cholesterol biosensor was constructed by bimetallic (Au and Pt) and poly(amidoamine)-zeolite imidazole framework (PAMAM-ZIF-67). First, PAMAM-ZIF-67 nanomaterial was immobilized onto the electrode, and then Au and Pt were modified on the electrode by the electro-deposition method. Subsequently, cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) were fixed on the electrode. The stepwise modification procedures were recorded by impedance spectroscopy and voltammetry. The current response presented a linear relation to the logarithm of cholesterol content when content ranged between 0.00015 and 10.24 mM, and the minimum detection concentration reached 3 nM. The electrode was also used for the cholesterol assay in serum, which hinted at its potentially valuable in clinical diagnostics. An electrochemical biosensor based on gold nanoparticles, platinum nanoparticles, and polyamide-zeolitic imidazolate frameworks was developed for detection of cholesterol. First, polyamide-zeolitic imidazolate frameworks nanomaterial was fixed onto the electrode modified of mercaptopropionic acid by Au-S bond. Then, gold nanoparticles and platinum nanoparticles were electrodeposited on the above electrode. Subsequently, cholesterol oxidase and cholesterol esterase were co-immobilized on the surface of the modified electrode to fabricate the cholesterol biosensor. The biosensor has also been used for the measurement of cholesterol in human serum, which implied potential applications in biotechnology and clinical diagnostics.

Dual Responsive Magnetic Drug Delivery Nanomicelles with Tumor Targeting for Enhanced Cancer Chemo/Magnetothermal Synergistic Therapy.

Introduction: Stimulus-responsive nanocarrier systems are promising in cancer treatment. They improve drug stability and facilitate controlled drug release. However, single-responsive nanocarriers still face insufficient tumor targeting and low efficacy. Methods: In this study, we synthesized folate-modified DSPE-PEOz nanomicelles with PEG chains and loaded them with magnetic iron particles and doxorubicin (DOX). Folic acid (FA) was employed as a ligand to target cancer cells actively. The nanomicelles are biocompatible and acid-sensitive drug carriers. Magnetic field-responsive nanoparticles enable moderately controlled magnetothermal therapy of tumors regardless of tumor location. The pH/magnetic field dual-responsive nanomicelles shed their PEG layer in response to tumor tissue acidity and react to magnetic fields through magnetothermal effects. Results: In vitro and in vivo experiments demonstrated that the nanomicelles could efficiently target cancer cells, release drugs in response to pH changes, and enhance drug uptake through magnetothermal effects. Discussion: The dual-responsive magnetic nanomicelles are expected to enhance the anti-cancer efficacy of chemo/magnetothermal synergistic therapy.

Recent advances in magnetic nanocarriers for tumor treatment.

Magnetic nanocarriers are nano-platforms that integrate multiple moieties based on magnetic nanoparticles for diagnostic and therapeutic purposes. In recent years, they have become an advanced platform for tumor treatment due to their wide application in magnetic resonance imaging (MRI), biocatalysis, magneto-thermal therapy (MHT), and photoresponsive therapy. Drugs loaded into magnetic nanocarriers can efficiently be directed to targeted areas by precisely reshaping their structural properties. Magnetic nanocarriers allow us to track the location of the therapeutic agent, continuously control the therapeutic process and eventually assess the efficacy of the treatment. They are typically used in synergistic therapeutic applications to achieve precise and effective tumor treatment. Here we review their latest applications in tumor treatment, including stimuli-responsive drug delivery, MHT, photoresponsive therapy, immunotherapy, gene therapy, and synergistic therapy. We consider reducing toxicity, improving antitumor efficacy, and the targeting accuracy of magnetic nanocarriers. The challenges of their clinical translation and prospects in cancer therapy are also discussed.

Biosensor based on bimetallic/graphene composite for non-enzymatic detection of hydrogen peroxide in living tumor cells.

A highly sensitive electrochemical biosensor was manufactured with triple synergistic catalysis to detect hydrogen peroxide (H2 O2 ). In this study, a highly sensitive biosensor based on Prussian blue-chitosan/graphene-hemin nanomaterial/platinum and palladium nanoparticles (PB-CS/HGNs/Pt&Pd biosensor) was fabricated for the detection of H2 O2 . The materials described above were modified on the electrode surface and applied to catalyze the breakdown of hydrogen peroxide. The current response of the biosensor presented a linear relationship with H2 O2 concentration from 6 × 10-2 to 20 µM (R2 = 0.9766) and with the logarithm of H2 O2 concentration from 20 to 9×103  µM (R2 = 0.9782), the low detection limit of 25 nM was obtained at the signal/noise (S/N) ratio of 3. Besides, the biosensor showed an outstanding anti-interference ability and acceptable reproducibility. PB-CS/HGNs/Pt&Pd electrodes are effective in measuring H2 O2 from living tumor cells, which implies that the biosensor has the potential to assess reactive oxygen species in various living tumor cells.

Graphene quantum dots mediated magnetic chitosan drug delivery nanosystems for targeting synergistic photothermal-chemotherapy of hepatocellular carcinoma.

Conventional clinical monotherapies for advanced hepatocellular carcinoma (HCC) have numerous limitations. Integrated oncology approaches can improve cancer treatment efficacy, and photothermal-chemotherapy drug delivery nanosystems (DDS) based on nanotechnology and biotechnology have piqued the interest of researchers. This study developed an aptamer-modified graphene quantum dots (GQDs)/magnetic chitosan DDS for photothermal-chemotherapy of HCC. The HCC aptamer and the EPR effect of nanoparticles, in particular, enable active and passive targeting of DDS to HCC. GQDs functioned as photosensitizers, effectively moderating photothermal therapy and inhibiting drug release during blood circulation. Magnetic chitosan demonstrated excellent drug encapsulation, acid sensitivity, and tumor imaging capabilities. Proper assembly of the units mentioned above enables precise combined therapy of HCC. This study indicates that DDS can significantly inhibit tumor growth while also extending the survival duration of tumor-bearing mice. The DDS (DOX-Fe3O4@CGA) shows strong synergistic tumor treatment potential, allowing for the exploration and development of novel HCC therapies.

A highly sensitive biosensor based on Au NPs/rGO-PAMAM-Fc nanomaterials for detection of cholesterol.

OBJECTIVE: This study aimed to construct a biosensor using Au nanoparticles (Au NPs) and reduced graphene-polyamide-amine-ferrocene (rGO-PAMAM-Fc) nanomaterials designed for rapid and sensitive detection of cholesterol. MATERIALS AND METHODS: In this study, a highly sensitive biosensor based on Au NPs/ rGO-PAMAM-Fc nanomaterials was manufactured for detection of cholesterol. The rGO-PAMAM-Fc and Au NPs were modified on the surface of the electrode and then coated with cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) to develop the ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor. RESULTS: The capability of rGO-PAMAM-Fc nanomaterials in fabricating a more efficient biosensor was validated through stability, selectivity and reproducibility checks. Under optimal conditions, the newly developed biosensor showed a linear relationship with logarithm of cholesterol concentration from 0.0004 to 15.36 mM (R 2=0.9986), and a low detection limit of 2 nM was obtained at the signal/noise ratio of 3. CONCLUSION: The ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor was successfully applied for the measurement of cholesterol in human serum, which implies that the biosensor has a potential application in clinical diagnostics.

A novel absorption spectrometric method, based on graphene nanomaterials, for detection of hepatocellular carcinoma-specific T lymphocyte cells.

INTRODUCTION: Detection of antigen-specific cytotoxic T lymphocytes (CTLs) is the foundation for understanding hepatocellular carcinoma immune pathology and hepatocellular carcinoma immunotherapy. However, the classical method for labeling CTLs, major histocompatibility complex (MHC)-peptide tetramer, has drawbacks and needs further improvement. MATERIALS AND METHODS: Here, as a new detection probe, a graphene-based MHC-peptide multimer was developed for sensitively and selectively identifying hepatocellular carcinoma-specific T-cells. To assess its detection efficiency, reduced graphene oxide (RGO) was functionalized with hemin and streptavidin to prepare a functionalized HRGO-streptavidin complex. Biotinylated MHC-peptide monomer was subsequently constructed onto HRGO to generate a detection probe for CTL labeling. The number of T-cells was detected through the reaction between HRGO and tetramethylbenzidine. RESULTS: Using HRGO/MHC-peptide multimers, the number of T-cells was efficiently detected in both the induction system in vitro and in peripheral blood of patients. CONCLUSION: HRGO/MHC-peptide multimers methodology has application prospects in the detection of antigen peptide-specific T cells.

Recent advances in CD8+ regulatory T cell research.

Various subgroups of CD8+ T lymphocytes do not only demonstrate cytotoxic effects, but also serve important regulatory roles in the body's immune response. In particular, CD8+ regulatory T cells (CD8+ Tregs), which possess important immunosuppressive functions, are able to effectively block the overreacting immune response and maintain the body's immune homeostasis. In recent years, studies have identified a small set of special CD8+ Tregs that can recognize major histocompatibility complex class Ib molecules, more specifically Qa-1 in mice and HLA-E in humans, and target the self-reactive CD4+ T ce lls. These findings have generated broad implications in the scientific community and attracted general interest to CD8+ Tregs. The present study reviews the recent research progress on CD8+ Tregs, including their origin, functional classification, molecular markers and underlying mechanisms of action.

Quantum dot/pMHC multimers vs. phycoerythrin/pMHC tetramers for identification of HLA-A*0201-restricted pHBV core antigen18-27-specific T cells.

Detection of human leukocyte antigens-A2-restricted p-hepatitis B virus (HBV) core antigen­specific cytotoxic T lymphocytes (CTLs) is important in the study of HBV immunopathogenesis and vaccine design. Currently, major histocompatibility complex (MHC) class I/peptide­(p) MHCI tetramers are considered the optimal tools to detect antigen­specific CTLs. However, the MHC­tetramer technique also has certain drawbacks and is under continuous development. The quantum dot (QD) bioconjugates nanotechnology with its unique inorganic­biological properties has been developing fast. However, QD/pMHC multimers have seldom been used for the identification of the C18­27 epitope, which is important in HBV infection. QD/pMHC multimers were synthesized by metal­affinity coordination and an avidin­biotin system. In the present study they were characterized by transmission electron microscopy, dynamic light scattering and fluorescence spectrophotometry. C18­27­specific CTLs were obtained by ex vivo expansion of CD8+ T cells. Cultured CTLs were tested for the secretion level of interferon (IFN)­Î³ by ELISA and for cytotoxicity by lactate dehydrogenase release assay. Then, the performance of phycoerythrin (PE)/pMHC tetramers and QD/pMHC multimers were compared by flow cytometry. The synthesized QD/pMHC multimers dispersed well and their emission spectrum exhibited only slight differences compared with original QDs. C18­27­specific CTLs not only secreted IFN­Î³ but also effectively targeted T2 cells pulsed with peptide C18­27. The frequencies of C18­27­specific CTLs determined by QD/pMHC multimers were higher compared with PE/pMHC tetramers. The present results suggested that QD/pMHC multimers may be able to characterize greater numbers of C18­27­specific CTLs with increased sensitivity compared to conventional strategies.

Enhanced anti-tumor immunity against breast cancer induced by whole tumor cell vaccines genetically modified expressing α-Gal epitopes.

Whole tumor cell vaccines have shown much promise, but demonstrated poor efficiency in phase III trials. In this study, we modified MDA-MB­231 tumor cells (MDA-MB­231Gal+) to express α-1, 3-galactosyltransferase (α-1, 3-GT) protein, to potentially enhance antitumor effect of whole tumor cell vaccines. MDA-MB­231 tumor cell vaccines were transfected with a reconstructed lentiviral containing α-1, 3-GT genes. Tumor growth, tumorigenesis and survival of Hu-NOD-SCID mice were observed when tumor-bearing mice were injected with tumor cell vaccines. Proliferation and apoptosis in MDA-MB­231 tumor xenografts were observed by immunohistochemistry. The levels of cytokine secretion in the serum of mice were tested by ELISA. CD8+ T cells infiltrating tumors were assessed by flow cytometry. MDA-MB­231Gal+ cells expressed active α-1, 3-GT and produced α-Gal in vitro. MDA-MB­231Gal+ cell vaccines suppressed tumor growth and tumorigenesis in immunized Hu-NOD-SCID mice. Additionally, decrease of TGF-ß, IL-10 and increase of INF-γ, IL-12 were observed in tumor cell vaccinated mice. Furthermore, the cell vaccines enhanced infiltration of cytotoxic CD8+ T cells in the tumor microenvironment of immunized mice. The MDA-MB­231Gal+ cell vaccines modified α-1, 3-GT genes improved the antitumor effect.

Highly sensitive detection of leukemia cells based on aptamer and quantum dots.

Detection of leukemia at the early stage with high sensitivity is a significant clinical challenge for clinicians. In the present study, we developed a sensitive detector consisting of the product of oligonucleotides hybridized with semiconductor quantum dots (QDs) to generate a stronger fluorescent signal so that leukemic cells can be captured. In the present study, a biotin-modified Sgc8 aptamer was used to identify CCRF-CEM cells, and then biotin-appended QDs were labeled with the aptamer via streptavidin and biotin amplification interactions. We described the complex as QDs-bsb-apt. CEM and Ramos cells were used to assess the specificity and sensitivity of the novel complex. These results revealed that the complex could be more effective in diagnosing leukemia at the early stage. In conclusion, an innovative structure based on aptamer and QDs for leukemia diagnosis was provided. It has the potential to image tumor cells in vitro or in vivo and to realize the early diagnosis of disease. Furthermore, it may be used to provide guidance for clinicians to implement individualized patient therapy.

Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells.

A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

An ATP Aptasensor Based on the Peroxidase-like Activity of Hemin/Graphene Oxide Nanosheets.

In the present work, a sensitive electrochemical aptasensor was designed for the detection of adenosine triphosphate (ATP) with hemin/graphene oxide nanosheets (HGNs). Firstly, the ATP aptamer was self-assembled on gold electrode surface, and then HGNs were captured to the modified electrode by π-π stacking. The captured HGNs could catalyze the disproportionation reaction of H2O2, and produced a detectable electrochemical signal by chronoamperometry. ATP was competitively bound to aptamer which led to the release of HGNs from the electrode surface after adding ATP. The decrease of the electrochemical signal, which was calculated by the difference of amperometric responses before and after incubation of ATP, provided a quantitative signal for ATP detection. A linear correlation was achieved between the difference of the amperometric responses and the logarithmic concentration of ATP ranging from 0.5 to 100 nM with a detection limit of 0.08 nM. Besides, the aptasensor also exhibited good selectivity toward ATP against other analogs.