Phospholipid–Graphene Nanoassembly as a Fluorescence Biosensor for Sensitive Detection of Phospholipase D Activity

Inorganic nanoparticles for photothermal treatment of cancer

In recent years, inorganic nanoparticles (NPs) have attracted increasing attention as potential theranostic agents in the field of oncology. Photothermal therapy (PTT) is a minimally invasive technique that uses nanoparticles to produce heat from light to kill cancer cells. PTT requires two essential elements: a photothermal agent (PTA) and near-infrared (NIR) radiation. The role of PTAs is to absorb NIR, which subsequently triggers hyperthermia within cancer cells. By raising the temperature in the tumor microenvironment (TME), PTT causes damage to the cancer cells. Nanoparticles (NPs) are instrumental in PTT given that they facilitate the passive and active targeting of the PTA to the TME, making them crucial for the effectiveness of the treatment. In addition, specific targeting can be achieved through their enhanced permeation and retention effect. Thus, owing to their significant advantages, such as altering the morphology and surface characteristics of nanocarriers comprised of PTA, NPs have been exploited to facilitate tumor regression significantly. This review highlights the properties of PTAs, the mechanism of PTT, and the results obtained from the improved curative efficacy of PTT by utilizing NPs platforms.

Electrochemically derived nanographene oxide activates endothelial tip cells and promotes angiogenesis by binding endogenous lysophosphatidic acid

Graphene oxide (GO) exhibits good mechanical and physicochemical characteristics and has extensive application prospects in bone tissue engineering. However, its effect on angiogenesis is unclear, and its potential toxic effects are heavily disputed. Herein, we found that nanographene oxide (NGO) synthesized by one-step water electrolytic oxidation is smaller and shows superior biocompatibility. Moreover, NGO significantly enhanced angiogenesis in calvarial bone defect areas in vivo, providing a good microenvironment for bone regeneration. Endothelial tip cell differentiation is an important step in the initiation of angiogenesis. We verified that NGO activates endothelial tip cells by coupling with lysophosphatidic acid (LPA) in serum via strong hydrogen bonding interactions, which has not been reported. In addition, the mechanism by which NGO promotes angiogenesis was systematically studied. NGO-coupled LPA activates LPAR6 and facilitates the formation of migratory tip cells via Hippo/Yes-associated protein (YAP) independent of reactive oxygen species (ROS) stimulation or additional complex modifications. These results provide an effective strategy for the application of electrochemically derived NGO and more insight into NGO-mediated angiogenesis.

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Electrochemically derived nanographene oxide (NGO) has good cytocompatibility without upregulating reactive oxygen species.

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NGO exhibits better dispersibility and couples with endogenous lysophosphatidic acid (LPA) in body fluid.

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NGO enhances the angiogenesis by recruiting endogenous LPA and promoting endothelial tip cell formation.

Lipid-Functionalized Graphene Loaded with hMnSOD for Selective Inhibition of Cancer Cells

Combination therapies utilize multiple mechanisms to target cancer cells to minimize cancer cell survival. Graphene provides an ideal platform for combination therapy due to its photothermal properties and high loading capacity for cancer-fighting molecules. Lipid functionalization of graphene extends its potential as a therapeutic platform by improving its biocompatibility and functionality. Previous studies involving graphene demonstrated its usage as a therapeutic vehicle; however, the effect of bare and engineered graphene structures on oxidative stress has not been comprehensively investigated. Because oxidative stress has been linked to cancer progression, it is vital to examine the generation of reactive oxygen species (ROS) in response to therapeutic platforms. This study functionalizes reduced graphene oxide (rGO) with lipids and the antioxidant enzyme human manganese superoxide dismutase (hMnSOD) and presents a detailed characterization of cellular responses to bare and functionalized rGO nanostructures in tumorigenic and nontumorigenic breast cell lines. Each cell type displayed distinct responses depending on whether they were normal, nonmetastatic, or metastatic cells. Bare rGO significantly reduced cell growth and substantially increased ROS production in all cell lines and instigated necrosis in metastatic breast cancer cells. Cell proliferation decreased in cancerous breast cells upon introduction of lipid-rGO, which correlated with peroxidation of lipids coating the rGO. In contrast, lipid-rGO nanostructures had minimal impact on proliferation and lipid peroxidation for normal breast cells. Lipid-rGO nanostructures with bound hMnSOD inhibited the proliferation of metastatic cancer cells while preventing necrosis and avoiding the negative side effects on normal cells associated with chemotherapeutic agents. Together, the results confirm the importance of functionalizing rGO for therapeutic applications and present an additional modality for the usage of graphene to selectively target cancer cells.

Assay of Phospholipase D Activity by an Amperometric Choline Oxidase Biosensor

A novel electrochemical method to assay phospholipase D (PLD) activity is proposed based on the employment of a choline biosensor realized by immobilizing choline oxidase through co-crosslinking on an overoxidized polypyrrole film previously deposited on a platinum electrode. To perform the assay, an aliquot of a PLD standard solution is typically added to borate buffer containing phosphatidylcholine at a certain concentration and the oxidation current of hydrogen peroxide is then measured at the rotating modified electrode by applying a detection potential of +0.7 V vs. SCE. Various experimental parameters influencing the assay were studied and optimized. The employment of 0.75% (v/v) Triton X-100, 0.2 mM calcium chloride, 5 mM phosphatidylcholine, and borate buffer at pH 8.0, ionic strength (I) 0.05 M allowed to achieve considerable current responses. In order to assure a controlled mass transport and, at the same time, high sensitivity, an electrode rotation rate of 200 rpm was selected. The proposed method showed a sensitivity of 24 (nA/s)⋅(IU/mL)⁻¹, a wide linear range up to 0.33 IU/mL, fast response time and appreciable long-term stability. The limit of detection, evaluated from the linear calibration curve, was 0.005 IU/mL (S/N = 3). Finally, due to the presence of overoxidized polypyrrole film characterized by notable rejection properties towards electroactive compounds, a practical application to real sample analysis can be envisaged.

Microfluidic manufacturing of surface-functionalized graphene oxide nanoflakes for gene delivery

Graphene oxide (GO) is a single-atomic-layered material made of a sheet of oxidized carbon atoms arranged in a honeycomb structure. Thanks to the notable physical and chemical properties of GO, GO-based nanomaterials have applications in many fields of research, including gene delivery. It has been reported that pristine GO can absorb single-stranded DNA and RNA through π-π stacking, which cannot be used as a gene carrier because it is hard to load double-stranded DNA (dsDNA). To tackle this issue, this work was aimed at developing a hybrid nanoparticle (NP) system made of GO coated with cationic lipids (hereafter referred to as GOCL) with suitable physical-chemical properties for gene delivery applications. To this end, nanosized GO flakes (nGO) were coated with the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) by microfluidic mixing. Comprehensive characterization of GOCL NPs was performed by a combination of dynamic light scattering (DLS), micro-electrophoresis and atom force microscopy (AFM). Our results show that GOCL NPs exhibit adequate size (<150 nm) and surface charge (ξ = +15 mV) for gene delivery purposes. Complexes made of GOCL NPs and plasmid DNA (pDNA) were used to transfect human cervical cancer cells (HeLa) and human embryonic kidney (HEK-293) cells. Pristine nGO and DOTAP cationic liposomes were used as a reference. GOCL NPs exhibited a similar TE but a much higher cell viability compared with DOTAP cationic liposomes. Confocal fluorescence microscopy provided a reasonable explanation for the superior performance of GOCL/DNA complexes showing that they are much more numerous, regular in size and homogeneously distributed than DOTAP/DNA complexes, thus splitting their gene payload over the entire cell population. Because of the imperative demand for efficient and safe nanocarriers, this study will contribute to the development of novel surface-functionalized GO-based hybrid gene vectors.

Biological recognition of graphene nanoflakes

The systematic study of nanoparticle-biological interactions requires particles to be reproducibly dispersed in relevant fluids along with further development in the identification of biologically relevant structural details at the materials-biology interface. Here, we develop a biocompatible long-term colloidally stable water dispersion of few-layered graphene nanoflakes in the biological exposure medium in which it will be studied. We also report the study of the orientation and functionality of key proteins of interest in the biolayer (corona) that are believed to mediate most of the early biological interactions. The evidence accumulated shows that graphene nanoflakes are rich in effective apolipoprotein A-I presentation, and we are able to map specific functional epitopes located in the C-terminal portion that are known to mediate the binding of high-density lipoprotein to binding sites in receptors that are abundant in the liver. This could suggest a way of connecting the materials' properties to the biological outcomes.

Adsorption and binding dynamics of graphene-supported phospholipid membranes using the QCM-D technique

We report on the adsorption dynamics of phospholipid membranes on graphene-coated substrates using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. We compare the lipid vesicle interaction and membrane formation on gold and silicon dioxide QCM crystal surfaces with their graphene oxide (GO) and reduced (r)GO coated counterparts, and report on the different lipid structures obtained. We establish graphene derivative coatings as support surfaces with tuneable hydrophobicity for the formation of controllable lipid structures. One structure of interest formed is lipid monolayer membranes which were formed on rGO, which are otherwise challenging to produce. We also demonstrate and monitor biotin-avidin binding on such a membrane, which will then serve as a platform for a wide range of biosensing applications. The QCM-D technique could be extended to both fundamental studies and applications of other covalent and non-covalent interactions in 2-dimensional materials.

Lipase, Phospholipase, and Esterase Biosensors (Review)

A biosensor is a device composed by a biological recognition element and a transducer that delivers selective information about a specific analyte. Technological and scientific advances in the area of biology, bioengineering, catalysts, electrochemistry, nanomaterials, microelectronics, and microfluidics have improved the design and performance of better biosensors. Enzymatic biosensors based on lipases, esterases, and phospholipases are valuable analytical apparatus which have been applied in food industry, oleochemical industry, biodegradable polymers, environmental science, and overall the medical area as diagnostic tools to detect cholesterol and triglyceride levels in blood samples. This chapter reviews recent developments and applications of lipase-, esterase-, and phospholipase-based biosensors.

A novel CuZnInS quantum dot-based ECL sensing system for lysophosphatidic acid detection

A novel ECL sensing system was developed for lysophosphatidic acid detection based on AGM-CuInZnS QDs and GNs.

Facile fabrication of a resveratrol loaded phospholipid@reduced graphene oxide nanoassembly for targeted and near-infrared laser-triggered chemo/photothermal synergistic therapy of cancer in vivo

A resveratrol-loaded phospholipid coated reduced graphene oxide was prepared using a sonication method.

Strong hydrophobic interaction between graphene oxide and supported lipid bilayers revealed by AFM

Understanding the interaction between graphene oxide (GO) and lipid membranes is of great importance for its various applications in biotechnology. Here, we investigated the interaction between GO and charged supported lipid bilayers (SLBs) by in situ atomic force microscope (AFM) imaging. It was found that GO could peel off a single layer of positively charged SLBs and deposited on the hydrophobic part of the remaining sublayer. Then free lipid molecules would assemble on GO surface and formed 1.5 bilayers in a lipid-GO-lipid manner. For negatively charged lipid bilayers, however, GO deposited to the SLBs only when its concentration was very high. These results indicate that, in addition to electrostatic interaction, the hydrophobic interaction plays an important role when GO sheets deposit onto the charged lipid bilayers, and should be helpful to understand possible cytotoxicity and antibiosis of graphene-related nanomaterials. Microsc. Res. Tech. 79:721-726, 2016. © 2016 Wiley Periodicals, Inc.

Effective isolation of exosomes with polyethylene glycol from cell culture supernatant for in-depth proteome profiling

Exosomes are secreted nanovesicles shed by almost all kinds of cells. Recently, increased interest has been focused on these extracellular vesicles as natural carriers transporting biological contents for intercellular communication. However, current isolation techniques, such as ultracentrifugation, are not convenient and often require specialized equipment. Herein, we describe a polyethylene glycol (PEG)-based approach, which could permit facile, low-cost and effective isolation of exosomes from cell culture supernatant. High-resolution electron microscopes clearly visualized the size and morphology of isolated exosome aggregates, implying the mechanism of PEG-based precipitation. Combined with tandem mass spectrometry analysis, 6299 protein groups encoded by 5120 genes were successfully characterized from HeLa cell culture supernatant, including numerous exosome proteins which could overlap 97% of the Top 100 exosome marker proteins recorded in the ExoCarta database, as well as a series of low-abundance cytokines and biomarkers. Furthermore, we found a higher ratio of neo-cleavage sites in proteins identified from exosomes compared with cellular proteins, revealing the potential roles of exosomes in accumulation and transportation of protein degradation intermediates.

Stimuli responsive charge-switchable lipids: Capture and release of nucleic acids

Stimuli responsive lipids, which enable control over the formation, transformation, and disruption of supramolecular assemblies, are of interest for biosensing, diagnostics, drug delivery, and basic transmembrane protein studies. In particular, spatiotemporal control over a supramolecular structure can be achieved using light activated compounds to induce significant supramolecular rearrangements. As such, a family of cationic lipids are described which undergo a permanent switch in charge upon exposure to 365 nm ultraviolet (UV) light to enable the capture of negatively charged nucleic acids within the self-assembled supramolecular structure of the lipids and subsequent release of these macromolecules upon exposure to UV light and disruption of the assemblies. The lipids are composed of either two different tripeptide head groups, Lysine-Glycine-Glycine (KGG) and Glycine-Glycine-Glycine (GGG) and three different hydrocarbon chain lengths (C6, C10, or C14) terminated by a UV light responsive 1-(2-nitrophenyl)ethanol (NPE) protected carboxylic acid. The photolysis of the NPE protected lipid is measured as a function of time, and the resulting changes in net molecular charge are observed using zeta potential analysis for each head group and chain length combination. A proof of concept study for the capture and release of both linear DNA (calf thymus) and siRNA is presented using an ethidium bromide quenching assay where a balance between binding affinity and supramolecular stability are found to be the key to optimal nucleic acid capture and release.

Quantum dot cluster (QDC)-loaded phospholipid micelles as a FRET probe for phospholipase A2 detection

A simple assay for phospholipase A2 (PLA2) enzyme was developed based on a fluorescence resonance energy transfer (FRET) probe using the quantum dot cluster (QDC)-loaded phospholipid micelles. The probe was prepared by encapsulating many small hydrophobic quantum dots (QDs) within the hydrophobic core of micelles that were formed from the coassembly of hydrogenated soy phosphatidylcholine phospholipids (HSPC) and fluorescent lipids (NBD-PC). QDCs formed within the micelle core served as the substrate for NBD fluorescence quenching through FRET. The QDC-loaded micelles showed very low background fluorescence. As the PLA2 enzyme selectively digested lipids, the NBD fluorescence was recovered from its quenched state, leading to the sensitive detection of PLA2. This assay provided a limit of detection (at a signal-to-noise ratio of 3) of 3 U/L for PLA2. In the presence of a PLA2 inhibitor, the fluorescent response of the sensor for PLA2 decreased, indicating that the assay could also be used for screening the PLA2 inhibitors.

Target-controlled gating liposome “off–on” cascade amplification for sensitive and accurate detection of phospholipase D in breast cancer cells with a low-background signal

Here we developed a simple, sensitive and accurate PLD detection method based on a target-controlled gating liposome (TCGL) “off–on” cascade amplified strategy and personal glucose meters (PGMs).

Preparation of a Three-Dimensional Reduced Graphene Oxide Film by Using the Langmuir-Blodgett Method

The Langmuir-Blodgett method has always been traditionally utilized in the deposition of two-dimensional structures. In this work, however, we employed the method to deposit three-dimensional reduced graphene oxide layers using an unconventional protocol for the first time. This was achieved by carrying out the dipping process after the collapse pressure or breaking point, which results in the formation of a highly porous three-dimensional surface topography. By varying the number of deposition layers, the porosity could be optimized from nanometer to micrometer dimensions. Employed as bioelectrodes, these three-dimensional reduced graphene oxide layers may allow improved adhesion and biocompatibility compared to the conventional two-dimensional surfaces. A larger number of pores also improves the mass transport of materials and therefore increases the charge-sustaining capacity and sensitivity. This could ultimately improve the performance of biofuel cells and other electrode-based systems.

Porphyrin-loaded liposomes and graphene oxide used for the membrane pore-forming protein assay and inhibitor screening

The interaction of planar aromatic molecules with the graphene oxide (GO) sheets is often marked by the fluorescence quenching of the former. Here, the α,β,γ,δ-tetrakis[4-(trimethylammoniumyl)phenyl]porphyrin (TAPP) molecules and the GO, corresponding to the energy donor and the acceptor respectively, are initially separated by encapsulating the TAPP molecules within the liposomes, to obstruct the formation of the self-assembled energy transfer-based quenching system. Upon disruption of the liposome membranes by the PLA2 or the α-toxin, the encapsulated TAPP molecules are released and subsequently result in significant fluorescence changes. Thus, a platform based on the fluorescence signal for monitoring the activity of the membrane pore-forming protein with advantages of high sensitivity and commonality was established. Using this strategy, we can detect the PLA2 and the α-toxin concentrations as low as 200 pM and 9.0 nM, respectively. Furthermore, by taking chlorpromazine and baicalin as the examples, we use the assay to evaluate the prohibition effects on the PLA2 and the α-toxin, and the IC50 values of chlorpromazine toward the PLA2 (9.6 nM) and that of baicalin toward the α-toxin (289.2 nM) were found to be 12.0 ± 0.62 μM and 26.9 ± 2.6 μM, respectively.

Phospholipid-modified upconversion nanoprobe for ratiometric fluorescence detection and imaging of phospholipase D in cell lysate and in living cells

Phospholipase D (PLD) is a critical component of intracellular signal transduction and has been implicated in many important biological processes. It has been observed that there are abnormalities in PLD expression in many human cancers, and PLD is thus recognized as a potential diagnostic biomarker as well as a target for drug discovery. We report for the first time a phospholipid-modified nanoprobe for ratiometric upconversion fluorescence (UCF) sensing and bioimaging of PLD activity. The nanoprobe can be synthesized by a facile one-step self-assembly of a phospholipid monolayer composed of poly(ethylene glycol) (PEG)ylated phospholipid and rhodamine B-labeled phospholipid on the surface of upconversion nanoparticles (UCNPs) NaYF4: 20%Yb, 2%Er. The fluorescence resonance energy transfer (FRET) process from the UCF emission at 540 nm of the UCNPs to the absorbance of the rhodamine B occurs in the nanoprobe. The PLD-mediated hydrolysis of the phosphodiester bond makes rhodamine B apart from the UCNP surface, leading to the inhibition of FRET. Using the unaffected UCF emission at 655 nm as an internal standard, the nanoprobe can be used for ratiometric UCF detection of PLD activity with high sensitivity and selectivity. The PLD activity in cell lysates is also determined by the nanoprobe, confirming that PLD activity in a breast cancer cell is at least 7-fold higher than in normal cell. Moreover, the nanoprobe has been successfully applied to monitoring PLD activity in living cells by UCF bioimaging. The results reveal that the nanoprobe provides a simple, sensitive, and robust platform for point-of-care diagnostics and drug screening in biomedical applications.

Gold nanoparticle supported phospholipid membranes as a biomimetic biosensor platform for phosphoinositide signaling detection

Enzyme mediated phosphoinositide signaling plays important regulatory roles in diverse cellular processes and has close implication in human diseases. However, detection of phosphoinositide enzymes remains a challenge because of the difficulty in discriminating the phosphorylation patterns of phosphoinositide. Here we develop a novel enzyme-activated gold nanoparticles (AuNPs) assembly strategy as a homogeneous colorimetric biosensor for activity detection of phosphoinositide kinases and phosphatases. This strategy utilizes a biomimetic mechanism of phosphoinositide signaling, in which AuNP supported phospholipid membranes are constructed to mimic the cellular membrane substrate, and AuNPs modified with the pleckstrin homology (PH) domain of cytosolic proteins are designed for specific, multivalent recognition of phosphorylated phosphoinositides. This biomimetic strategy enables efficient enzymatic reactions of the substrate and highly selective detection of target enzyme. The biosensor is demonstrated for the detection of phosphoinositide 3-kinase (PI3K) and phosphatase with tensin homology (PTEN). The results revealed that it allows sensitive, rapid visual detection of the enzymes with pM detection limits and four-decade wide dynamic ranges, and is capable of detecting enzyme activities in complex cell lysate samples. This biosensor might provide a general biosensor platform for high-throughput detection of phosphoinositide enzymes with high sensitivity and selectivity in biomedical research and clinical diagnostics.

Morphology change and detachment of lipid bilayers from the mica substrate driven by graphene oxide sheets

Understanding the interaction between graphene oxide (GO) and a lipid membrane is significant for exploring the biocompatibility and cytotoxicity of GO, which is the basis for utilizing GO in the fields of biosensors, bioimaging, drug delivery, antibacterials, and so on. In this article, we monitored the dynamic process of the morphology change and detachment of lipid bilayers on mica substrates prompted by GO sheets by in situ atomic force microscope (AFM) imaging. It was found that the bare lipid bilayer dramatically expanded in height and would be unstable and detachable from the mica substrates as induced by GO. The detached lipid molecules were found to bind to the GO surface. The results also imply that GO is likely to influence the height and stability of the supported lipid bilayers (SLBs) by adsorbing metal ions such as calcium ions that were used to stabilize the bilayer structures on the mica substrate. These findings illustrate a complicated effect of GO on the SLBs and should be helpful in future applications of GO in biotechnology.

Graphene–hemin hybrid nanosheets as a label-free colorimetric platform for DNA and small molecule assays

A novel colorimetric platform has been developed for detecting DNA and small molecules based on a graphene–hemin hybrid nanosheet in a homogenous solution.

Graphene nanoflakes as an efficient ionizing matrix for MALDI-MS based lipidomics of cancer cells and cancer stem cells

This study demonstrates that graphene nanoflakes can be efficiently used as a successful, interference free matrix for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS).

A single-stage functionalization and exfoliation method for the production of graphene in water: stepwise construction of 2D-nanostructured composites with iron oxide nanoparticles

A practically simple top-down process for the exfoliation of graphene (GN) and few-layer graphene (FLG) from graphite is described. We have discovered that a biocompatible amphiphilic pyrene-based hexahistidine peptide is able to exfoliate, functionalize, and dissolve few layer graphene flakes in pure water under exceptionally mild, sustainable and virtually innocuous low intensity cavitation conditions. Large area functionalized graphene flakes with the hexahistidine oligopeptide (His₆-TagGN = His₆@GN) have been produced efficiently at room temperature and characterized by TEM, Raman, and UV spectroscopy. Conductivity experiments carried out on His₆-TagGN samples revealed superior electric performances as compared to reduced graphene oxide (rGO) and non-functionalized graphene, demonstrating the non-invasive features of our non-covalent functionalization process. We postulated a rational exfoliation mechanism based on the intercalation of the peptide amphiphile under cavitational chemistry. We also demonstrated the ability of His6-TagGN nanoassemblies to self-assemble spontaneously with inorganic iron oxide nanoparticles generating magnetic two-dimensional (2D) His₆-TagGN/Fe₃O₄ nanocomposites under mild and non-hydrothermal conditions. The set of original experiments described here open novel perspectives in the facile production of water dispersible high quality GN and FLG sheets that will improve and facilitate the interfacing, processing and manipulation of graphene for promising applications in catalysis, nanocomposite construction, integrated nanoelectronic devices and bionanotechnology.

Synthesis of fluorescent gold nanodot-liposome hybrids for detection of phospholipase C and its inhibitor

We report the synthesis of fluorescent 11-mercaptoundecanoic acid-gold nanodot-liposome (11-MUA-Au ND/Lip) hybrids by incorporation of gold nanoparticles (∼3 nm) and 11-MUA molecules in hydrophobic phospholipid membranes that self-assemble to form small unilamellar vesicles. A simple and homogeneous fluorescence assay for phospholipase C (PLC) was developed on the basis of the fluorescence quenching of 11-MUA-Au ND/Lip hybrids in aqueous solution. The fluorescence of the 11-MUA-Au ND/Lip hybrids is quenched by oxygen (O2) molecules in solution, and quenching is reduced in the presence of PLC. PLC catalyzes the hydrolysis of phosphatidylcholine units from Lip to yield diacylglycerol (DAG) and phosphocholine (PC) products, leading to the decomposition of Lip. The diacylglycerol further interacts with 11-MUA-Au NDs via hydrophobic interactions, leading to inhibition of O2 quenching. The 11-MUA-Au ND/Lip probe provides a limit of detection (at a signal-to-noise ratio of 3) of 0.21 nM for PLC, with high selectivity over other proteins, enzymes, and phospholipases. We have validated the practicality of using this probe for the determination of PLC concentrations in breast cancer cells (MCF-7 and MDA-MB-231 cell lines) and nontumor cells (MCF-10A cell line), revealing that the PLC activity in the first two is at least 1.5-fold higher than that in the third. An inhibitor assay using 11-MUA-Au ND/Lip hybrids demonstrated that tricyclodecan-9-yl potassium xanthate (D609) inhibits PLC (10 nM) with an IC50 value of 3.81 ± 0.22 μM. This simple, sensitive, and selective approach holds great potential for detection of PLC in cancer cells and for the screening of anti-PLC drugs.