Reticular Heterojunction for Organic Photoelectrochemical Transistor Detection of Neuron-Specific Enolase.

Reticular heterojunctions on the basis of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have sparked considerable interest in recent research endeavors, which nevertheless have seldom been studied in optoelectronic biosensing. In this work, its utilization for organic photoelectrochemical transistor (OPECT) detection of the important cancer biomarker of neuron-specific enolase (NSE) is reported. A MOF@COF@CdS quantum dots (QDs) heterojunction is rationally designed to serve as the photogating module against the polymeric channel. Linking with a sandwich complexing event, target-dependent alternation of the photogate is achieved, leading to the changed photoelectric conversion efficiency as indicated by the amplified OPECT signals. The proposed assay demonstrates good analytical performance in detecting NSE, featuring a linear detection range from 0.1 pg mL-1 to 100 ng mL-1 , with a detection limit of 0.033 pg mL-1 .

Selective identification of p-nitroaniline by bromine-mediated polarization of carbon dots.

A fluorometric method based on boron, bromide-codoped carbon dots (BBCNs) was developed for the first time for the highly selective detection of p-nitroaniline (PNA) in wastewater samples. It should be noted that the introduction of bromine greatly increases the molecular polarizability of the probe, which can regulate the energy level matching between the probe and PNA, resulting in the interaction between BBCNs and PNA. In the presence of PNA, the fluorescence of BBCNs is obviously quenched and accompanied by a red shift of the fluorescence band, which might be attributed to the formation of aggregates caused by the polar adsorption of BBCNs and PNA. It is beneficial for constructing a highly selective sensing platform for PNA determination compared to its isomers (o-nitroaniline and m-nitroaniline) through atomic bromine-mediated polarization of the BBCNs. With the help of this mechanism, an excellent linear range of 0.5-300 µM with a low detection limit of 0.24 µM toward PNA was obtained. This work further confirms that there is a significant relationship between the nature of doping elements and the optical and physicochemical properties of fluorescent materials.

Photoelectrochemical detection of copper ions based on a covalent organic framework with tunable properties.

Copper ions (Cu2+) play an essential role in various cellular functions, including respiration, nerve conduction, tissue maturation, oxidative stress defense, and iron metabolism. Covalent organic frameworks (COFs) are a class of porous crystalline materials with directed structural designability and high stability due to the combination of different monomers through covalent bonds. In this study, we synthesized a porphyrin-tetrathiazole COF (TT-COF(Zn)) with Zn-porphyrin and tetrathiafulvalene (TTF) as monomers and used it as a photoactive material. The strong light absorption of metalloporphyrin and the electron-rich properties of supplied TTF contribute to its photoelectrochemical performance. Additionally, the sulfur (S) in the TTF can coordinate with Cu2+. Based on these properties, we constructed a highly sensitive photoelectrochemical sensor for detecting Cu2+. The sensor exhibited a linear range from 0.5 nM to 500 nM (R2 = 0.9983) and a detection limit of 0.15 nM for Cu2+. Notably, the sensor performed well when detecting Cu2+ in water samples.

One-pot green preparation of deep-ultraviolet and dual-emission carbon nanodots for dual-channel ratiometric determination of polyphenol in tea sample.

A novel deep-ultraviolet and dual-emission carbon nanodots (DUCDs)-based dual-channel ratiometric probe was prepared by a one-pot environmental-friendly hydrothermal process using guanidine as the only starting material for sensing polyphenol in tea sample (TPPs). Under the exposure to TPPs, the DUCDs not only provided a characteristic colorimetric response to TPPs, but also displayed TPPs-sensitive ratiometric fluorescence quenching. The detection mechanism was proved to be that enrichment-specific hydroxyl sites (e.g., -NH2 and -COOH) of DUCDs can specifically react with phenolic hydroxyl groups of TPPs to generate dynamic amide and carboxylate bonds by dehydration and/or condensation reaction. As a result, a new carbon nanomaterial with decrement of surface passivation groups, inherent light-absorbing, and invalid fluorescence emission was generated. The ratio (FL297nm/FL395nm) of fluorescence intensity at 297 nm and 395 nm of DUCDs excited at 275 nm decreased with increasing TPPs concentration. The linearity range was 5.0 ng/mL to 100 µg/mL with a detection limit (DL) of 3.5 ± 0.04 ng/mL for TPPs (n = 3, 3σ/k). Colorimetry of DUCDs, best measured as absorbance at 320 nm, was increased linearly in the TPP concentration range 200 ng/mL-200 µg/mL with a DL of 94.7 ± 0.04 ng/mL (n = 3, 3σ/k). The probe was successfully applied to the determination of TPPs in real tea samples, showing potential application prospects in food analysis.

Green synthesis of a deep-ultraviolet carbonized nanoprobe for ratiometric fluorescent detection of feroxacin and enrofloxacin in food and serum samples.

Recently, the development of a novel fluorescent (FL) nanoprobe for ratiometric detection of antibiotics in real-world samples has received more and more attention. In this article, the distinctive optical properties of deep-ultraviolet emission, a narrowed full width at half maximum (∼20 nm) and excitation-independent emission of a carbonized nanoprobe (CNP) were easily prepared by an environmentally friendly approach of solvothermal treatment using melamine as the precursor and H2O as the solvent. The obtained CNP can be further utilized as an efficient ratiometric FL nanoprobe for enrofloxacin (EFC) and feroxacin (FXC) detection based on the fact that the FL quenching of the CNP was accompanied by an FL increase with EFC/FXC based on the inner filter effect (IFE). Under the optimal conditions, excellent linear relationships existed between the relative FL intensity (FL290 nm/FL412 nm, CNP for FL290 nm and antibiotics for FL412 nm) and the concentrations of FXC and EFC in the range of 0.05-500.0 µM and 0.05-200.0 µM, with limits of detection of 21.74 and 22.43 nM (3σ/k), respectively. With the proposed ratiometric FL sensor, FXC and EFC in milk and serum samples can be rapidly and selectively analyzed without tedious pretreatment processes for real-world samples.

Ratiometric detection of p-nitrophenol and its derivatives using a dual-emissive neuron cell-like carbonized probe based on a ππ stacking quenching mechanism.

p-Nitrophenol and its derivatives can cause serious harm to the health of mankind and the earth's ecosystem. Therefore, it is necessary to develop a novel and rapid detection technology for p-nitrophenol and its derivative. Herein, excellent water-soluble, large-size and dual-emissive neuron cell-analogous carbon-based probes (NCNPs) have been prepared via a solvothermal approach, using o-phenylenediamine as the only precursor, which exhibit two distinctive fluorescence (FL) peaks at 420 and 555 nm under 345 nm excitation. The NCNPs show a neuron cell-like branched structure, are cross-connected, and are in the range of 10-20 nm in skeleton diameter. Interestingly, their blue-green dual-colour fluorescence is quenched by p-nitrophenol or its derivative due to the specific mechanism of the ππ stacking interactions or internal filtration effect. Accordingly, a simple, rapid, direct and free-label ratiometric FL detection of p-nitrophenol is proposed. An excellent linear relationship shows linear regions over the range of 0.1-50 µM between the ratio of the FL intensity (FL555 nm/FL420 nm) and the concentrations of p-nitrophenol. The detection limit is as low as 43 nM (3σ). Importantly, the NCNP-based probe also shows acceptable repeatability and reproducibility for the detection of p-nitrophenol and its derivatives, and the recovery results for p-nitrophenol in real wastewater samples are favourable.

Enzymatic photoelectrochemical bioassay based on hierarchical CdS/NiO heterojunction for glucose determination.

The design and development of a 3D hierarchical CdS/NiO heterojunction and its application in a self-powered cathodic photoelectrochemical (PEC) bioanalysis is introduced. Specifically, NiO nanoflakes (NFs) were in situ formed on carbon fibers via a facile liquid-phase deposition method followed by an annealing step and subsequent integration with CdS quantum dots (QDs). The glucose oxidase (GOx) was then coated on the photocathode to allow the determination of glucose. Under 5 W 410 nm LED light and at a working voltage of 0.0 V (vs. Ag/AgCl), this method can assay glucose concentrations down to 1.77×10-9 M. The linear range was 5×10-7 M to 1×10-3 M, and the relative standard deviation (RSD) was below 5%. The photocathodic biosensor achieved target detection with high sensitivity and selectivity. This work is expected to stimulate more passion in the development of innovative hierarchical heterostructures for advanced self-powered photocathodic bioanalysis. Design of 3D hierarchical CdS/NiO heterojunction and its application in a self-powered cathodic photoelectrochemical (PEC) bioanalysis.

Au-Hg/rGO with enhanced peroxidase-like activity for sensitive colorimetric determination of H2O2.

The Au-Hg amalgam anchored on the surface of reduced graphene oxide nanosheets (Au-Hg/rGO) has been synthesized successfully and characterized by various techniques such as transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The Au-Hg/rGO nanocomposites were found to possess excellent peroxidase-like catalytic activity and can quickly catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB in the presence of H2O2. The obvious color change offered accurate determination of the H2O2 concentration by recording the absorbance at 652 nm using a UV-vis spectrophotometer. The linear response range for H2O2 was from 5 µM to 100 µM and the detection limit was 3.25 µM (S/N = 3). Furthermore, a kinetic study indicated that the catalytic behavior of Au-Hg/rGO nanocomposites followed the typical Michaelis-Menten theory and Au-Hg/rGO nanocomposites showed good affinity for H2O2. We envision that the simple and sensitive colorimetric detection system holds great promising applications in clinical diagnostics and food and environment monitoring.

UV-assisted one-pot synthesis of bimetallic Ag-Pt decorated reduced graphene oxide for colorimetric determination of hydrogen peroxide.

Bimetallic Ag-Pt nanoparticles decorated on the surface of reduced graphene oxide (Ag-Pt/rGO) were designed and selected as a nanozyme for the assay of hydrogen peroxide. The nanocomposites were prepared through a one-pot reduction of potassium chloroplatinate, silver nitrate, and graphene oxide under ultraviolet irradiation without using any extra chemical reducing agents or surfactants. The successful formation of Ag-Pt/rGO nanocomposites was confirmed by transmission electron microscopy, energy disperse spectroscopy mapping, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. Significantly, Ag-Pt/rGO nanocomposites possessed excellent peroxidase-like activity toward the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine to form a blue product in the presence of hydrogen peroxide. Steady-state kinetics studies suggested that Ag-Pt/rGO nanocomposites had high affinity to hydrogen peroxide. Based on these properties, a convenient and sensitive method for the colorimetric determination of hydrogen peroxide was developed. Under optimal conditions, the absorbance at 652 nm increases linearly in the 10-100 µM and 100 µM-1 mM ranges of hydrogen peroxide concentration, and the detection limit is 0.9 µM (S/N = 3). The method was successfully applied to the determination of hydrogen peroxide in real water samples. Graphical abstract Ag-Pt/rGO nanocomposites were prepared by a one-pot UV irradiation method and used as a novel nanozyme for colorimetric determination of H2O2.

One-pot green and simple synthesis of actinian nickel-doped carbon nanoflowers for ultrasensitive sensing of quercetin.

In this contribution, a one-pot method possessing the advantages of easy preparation, rapidness, efficiency and environmental friendliness has been developed for the first time for the facile synthesis of highly fluorescent actinian nickel-doped carbon nanoflowers (Ni-CNFWs) by using nickel(ii)acetylacetonate as a metal-carbon source. Various characterization studies indicate that metal nickel atoms have been successfully doped into carbon nanoflower frameworks with a weight percentage of 1.46 wt%. The Ni-CNFWs showed a "shell-core" actinian structure with ∼400 nm diameter and highly efficient fluorescence quenching ability in the presence of quercetin (Qut) due to the formed Meisenheimer complexes via the conjugation effect of p, π-electrons between Ni-CNFWs and Qut, which allowed the analysis of Qut in a very facile method. Under the optimal conditions, the decreased fluorescence of Ni-CNFWs showed a good linear relationship with the concentration of Qut ranging from 0.5 to 300.0 µM, and the limit of detection was 0.137 µM (3σ/k). Finally, the content of Qut in bovine serum was successfully detected with the novel on-off sensor, and the recoveries were 97.3-101.9%, which indicate that the constructed on-off sensor has a high selectivity and accuracy.

Carbon nanospheres with dual-color emission and their application in ratiometric pyrophosphate sensing.

Herein, we employ pH-dependent solubility equilibrium to develop the one-pot aqueous synthesis of dual-color emission fluorescent carbon nanosphere (DFCSs) with novel physicochemical properties. Unexpectedly, some of the DFCSs have a regular nanosphere shape, containing uniform carbon dots (∼20 nm) on their surface. This may be attributed to the change in the surface composition of the carbon nanospheres under the strong alkaline conditions (pH 13), which results in dual-wavelength emission by single-wavelength excitation. Interestingly, the fluorescence intensities of the two emission peaks of the DFCSs at 315/410 nm can be simultaneously quenched upon the addition of Co2+ due to the strong coordination between Co2+ and the O-containing luminescent groups from the carbon dots and DFCSs. Also, the results demonstrate that one Co2+ simultaneously combines with two chromophoric groups. Furthermore, the quenched DFCSs exhibit high sensitivity for pyrophosphate (PPi) in the range of 0.075-200.0 µM through a fluorescence recovery process, which can be attributed to the stronger Co2+-O[double bond, length as m-dash]P bond. This results in the removal of Co2+ from the surface of DFCSs-Co2+ system via competitive adsorption interactions. Meanwhile, this sensor shows high selectivity for PPi over mercapto amino acid and phosphate in aqueous solution. These results indicate the DFCSs can act as a dual-signal PPi-selective sensor via a ratiometric competitive mechanism.

Excitation-independent emission carbon nanoribbon polymer as a ratiometric photoluminescent probe for highly selective and sensitive detection of quercetin.

In this study, sulfur-nitrogen co-doped carbon nanoribbon (SNCNR) polymers with stable dual-emission fluorescence were synthesized using a one-step traditional hydrothermal method of 6-mercaptopurine in an aqueous methanol solution. Unexpectedly, the as-prepared SNCNRs with excitation-independent emission, as carbon nanomaterial derivatives, showed stable dispersions of a reticular-like shape and different lengths in the skeleton diameter. Compared with other carbon nanomaterials, the SNCNRs dramatically improved the electronic properties and surface chemical reactivities, and exhibited a sensitive ratiometric response to quercetin (Que) because of the Meisenheimer-like complexes formed through π-π stacking and electrostatic interaction. By using this SNCNR sensor, excellent ratiometric linear relationships (FL345 nm/FL420 nm) existed between the degree of quenching of the SNCNRs and the concentrations of Que in the range of 50.0 nM to 200 µM, and the limit of detection was 21.13 nM (3σ/k). Meanwhile, this sensor shows high selectivity for Que over other biomolecules, most amino acids and metal ions under the same conditions. Finally, this fluorescent probe was successfully applied to the direct analysis of Que in bovine serum and some beverage samples, which showed that it has potential for use in applications in clinical diagnosis and food analysis, and may pave the way for the design of effective fluorescent probes for other biologically related targets and food protection.

An OFF-ON detection method for copper(ii) ions using a AgAu-NG nanocomposite modified electrode.

An OFF-ON detection method for Cu2+ was developed at the AgAu bimetallic nanoparticle decorated nitrogen-doped graphene (AgAu-NG) nanocomposite modified electrode. The measurement was based on the copper-catalyzed oxidation of cysteamine (Cys) to regulate the oxidation peak current of Ag. In the absence of Cu2+, Cys can bind to the surface of AgAu-NG via the Ag-S or Au-S bond, thus leading to an obvious decrease of the oxidation peak current of Ag. However, in the presence of Cu2+, Cu2+ can greatly catalyze the oxidation of Cys by dissolved O2 to form cystamine, which would fall off the surface of AgAu-NG nanocomposites, leading to the partial recovery of the oxidation peak current of Ag. With the increase in the concentration of Cu2+, the oxidation peak current of Ag in the presence of Cys increases accordingly. So, the concentration of Cu2+ can be measured. By using the optimum conditions, this method can detect Cu2+ concentrations down to 0.3 nM (S/N = 3) with a linear response range of 1 nM-1 mM. Furthermore, this method was applied to determine Cu2+ concentrations in river water samples and showed excellent analytical performance.

A novel electrochemical sensor based on Au nanoparticles/8-aminoquinoline functionalized graphene oxide nanocomposite for paraquat detection.

In this paper, a novel electrochemical sensor based on Au nanoparticles/8-aminoquinoline functionalized graphene oxide (AuNPs/GAQ) nanocomposite was developed and tested for the first time for detection of paraquat (PQ). The morphology and composition of AuNPs/GAQ nanocomposite were characterized by various techniques, including transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. Cyclic voltammetry and differential pulse voltammetry were utilized to investigate the electrochemical performances of AuNPs/GAQ nanocomposite modified glassy carbon electrode. The obtained modified electrode exhibited excellent electrocatalytic activity towards detection of PQ. Under the optimized conditions, the proposed sensor showed low detection limit (6 nM, S/N = 3), wide linear range (0.02-24 µM), high selectivity and good stability. In addition, it was successfully applied for detection of PQ in natural water samples with satisfactory results.

An electrochemical daunorubicin sensor based on the use of platinum nanoparticles loaded onto a nanocomposite prepared from nitrogen decorated reduced graphene oxide and single-walled carbon nanotubes.

A glassy carbon electrode (GCE) was modified with a nanocomposite prepared from nitrogen-doped reduced graphene oxide (N-rGO) and single walled carbon nanotubes (SWCNTs), and then loaded with platinum nanoparticles (Pt NPs) to obtain a voltammetric sensor for daunorubicin (DNR). Reductive doping of GO and the crystallization of the Pt NPs were carried out in a one-step hydrothermal process. The modified electrode was characterized by cyclic voltammetry and differential pulse voltammetry. It exhibited high sensitivity compared with unmodified electrode. Some experimental parameters which affected sensor response were optimized. Under optimum conditions and at a working voltage of typically -0.56 V (vs. Ag/AgCl), the sensor has a low detection limit (3 ng mL-1), a wide linear range (0.01-6 µg mL-1) and good long-term stability. The method was successfully applied to the sensitive and rapid determination of DNR in spiked human serum samples. Graphical abstract Platinum nanoparticles were loaded onto a nanocomposite prepared from nitrogen decorated reduced graphene oxide and single-walled carbon nanotubes (N-rGO-SWCNTs-Pt) and then used for electrochemical determination of daunorubicin (DNR).

Fluorometric and colorimetric determination of hypochlorite using carbon nanodots doped with boron and nitrogen.

Carbon nanodots doped with boron and nitrogen (BN-CDs) with an average diameter of around 11 nm were prepared by a hydrothermal approach using adenine and 3-aminobenzene boronic acid as the starting materials. The atomic ratio of boron to nitrogen atomic in the BN-CDs is approximately 1:1. This indicates that a large fraction of N atoms goes lost during preparation because the B/N ratio of the precursors is about 1:6. The BN-CDs display blue fluorescence (best measured at excitation/emission wavelengths of 305/380 nm) which is independent of the excitation wavelength. On exposure to hypochlorite anion, fluorescence is quenched and the color of the solutions changes from yellow to brown. Fluorescence drops linearly in the 0.1-1000 µM hypochlorite concentration range. The colorimetric response, best measured as the absorbance ratio at 236/260 nm, ranges from 0.3 to 4.0 mM. The color changes can be readily detected visually. The probe was applied to the determination of hypochlorite in living cells and in (spiked) tap water. Graphical abstract Excitation wavelength-independent fluorescent boron and nitrogen codoped carbon nanodots (BN-CDs) were obtained by a hydrothermal approach. The BN-CDs were used to detect hypochlorite in wastewater by a fluorometric and colorimetric dual-readout assay.

Voltammetric simultaneous determination of catechol and hydroquinone using a glassy carbon electrode modified with a ternary hybrid material composed of reduced graphene oxide, magnetite nanoparticles and gold nanoparticles.

An electrochemical sensor is described for the simultaneous determination of the pollutants catechol (CC) and hydroquinone (HQ). A glassy carbon electrode (GCE) was modified with reduced graphene oxide, Fe3O4 and gold nanoparticles and then showed a pair of well-defined voltammetric peaks for CC and HQ. Its oxidation peak potentials (located at 0.21 and 0.10 V vs. Ag/AgCl) are well separated, and this makes it suitable for simultaneous determination of the two isomers. Under optimal conditions, the oxidation peak currents of CC and HQ increase linearly in the 0.05-550 µM and 0.1-500 µM concentration ranges, even in the presence of 0.1 mM of the respective other isomer. The detection limits are 0.02 and 0.17 µM (at S/N = 3), respectively. The modified GCE exhibits good selectivity and recovery when applied for the analysis of spiked wastewater. Graphical abstract Ternary hybrid nanomaterials of rGO-Fe3O4-Au was developed for simultaneous electrochemical determination of catechol (CC) and hydroquinone (HQ).

Photoluminescent coral-like carbon-branched polymers as nanoprobe for fluorometric determination of captopril.

The authors describe the synthesis of fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus. Uric acid and phosphoric acid act as nitrogen and phosphorus sources, respectively. The PCNBPs have a coral-like branched structure, are cross-connected, and < 20 nm in skeleton diameter. Their blue fluorescence, best measured at excitation/emission wavelengths of 330/425 nm, is quenched by mercury (II) ions due to the specifically restricted rigid conformation caused by the interaction of phosphorus, nitrogen, and oxygen groups on the surface of the PCNBPs. Fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (CAP) in the range 50 nM to 40 µM concentration range. Fluorescence recovery is attributed to the effectively specific interactions between the thiol group of CAP and Hg(II). The method was applied to the determination of the concentration of Cap in pharmaceutical samples, and recoveries were between 97.6 and 105.1%. Graphical abstract Fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus are described. Their fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (Cap) in the range 50 nM to 40 µM concentration range.

Near-Ultraviolet Fluorescent "ON-OFF-ON" Switching Sensors Based on Nitrogen-Enriched Dual-Color Single-Functional Polymer Carbon Nanosheets.

Graphene quantum-dot-like structures of highly enriched N-based dual-color single-functional polymer carbon nanosheets (GLNPCNs) with an average diameter as large as 170 nm (ca. five layers) are prepared through a facile hydrothermal method. Intermolecular C5 H5 N5 ⋅⋅⋅C5 H5 N5 and/or C2 H5 OH chemical polymerization interactions in the liquid state of the peripheral crown-ether-like "hole"-decorated compound GLNPCNs lead to a fascinating 2 D supramolecular polymer architecture, which exhibits near-ultraviolet (NUV) fluorescence, ultrahigh brightness, a narrow full-width at half-maximum, and excellent potential for practical applications. The unique NUV fluorescence of the GLNPCNs might be attributed to the "self-passivated" crown-ether-like layer on their surface; the GLNPCNs exhibit properties independent of the excitation wavelength, which is unexpected in the NUV region. Moreover, these GLNPCNs show highly selective and sensitive detection of hazardous and toxic silver (Ag+ ) ions, and discriminate other metal ions or anions in the range 1.5 nm to 50 µm through a fluorescence quenching response. The high sensing selectivity toward Ag+ ions could be attributable to the restricted rigid conformation of the peripheral crown-ether-like "hole", which binds exclusively to the Ag+ ion. In addition to Ag+ ion sensing, the GLNPCNs quenched by Ag+ ions exhibit high selectivity and sensitivity for cysteine (Cys) in the range 2.0 nm to 50 µm through a fluorescence recovery process, which could be attributed to the effective coordination/chelation interactions between Ag+ ions and the plentiful mercapto and amino groups of Cys. Our results suggest that the facile preparation, biocompatibility, outstanding photoluminescence, and physicochemical properties of these GLNPCNs make them potentially useful in numerous applications such as bioimaging, optical and electrochemical sensors, and energy devices.

Unique Roles of Gold Nanoparticles in Drug Delivery, Targeting and Imaging Applications.

Nanotechnology has become more and more potentially used in diagnosis or treatment of diseases. Advances in nanotechnology have led to new and improved nanomaterials in biomedical applications. Common nanomaterials applicable in biomedical applications include liposomes, polymeric micelles, graphene, carbon nanotubes, quantum dots, ferroferric oxide nanoparticles, gold nanoparticles (Au NPs), and so on. Among them, Au NPs have been considered as the most interesting nanomaterial because of its unique optical, electronic, sensing and biochemical properties. Au NPs have been potentially applied for medical imaging, drug delivery, and tumor therapy in the early detection, diagnosis, and treatment of diseases. This review focuses on some recent advances in the use of Au NPs as drug carriers for the intracellular delivery of therapeutics and as molecular nanoprobes for the detection and monitoring of target molecules.