Aqueous Nanoparticle Suspensions Research Articles

Electrochemistry Beyond Solutions: Modeling Particle Self-Crowding of Nanoparticle Suspensions.

Nanoparticle suspensions hold promise to transform functionality of next-generation electrochemical systems including batteries, capacitors, wastewater treatment, and sensors, challenging the limits of existing electrochemical models. Classical solution-based electrochemistry assumes that charge is transported and transferred by point-like carriers. Herein, we examine the electrochemistry of a model aqueous suspension of nondissolvable electroactive nanoparticles over a wide concentration range using a rotating disk electrode. Past a concentration and rotation rate threshold, the electrochemistry deviates from solution theory with a maximum attainable current due to particle "self-crowding" where reacted particles on the electrode surface reduce the area accessible for charge transfer by unreacted particles. The observed response is rationalized with an analytical model considering the physical adsorption/desorption kinetics and interfacial transport of nondissolvable finite-size charge carriers. Experimental validation shows the model to be applicable across a range of electrode sizes and thus suitable for engineering electrochemical systems employing nondissolvable nanoparticle suspensions.

BIO 300: A Prophylactic Radiation Countermeasure for Acute Radiation Syndrome.

Exposure to high doses of ionizing radiation can result in hematopoietic acute radiation syndrome. Currently, there is no radiation medical countermeasure approved by the U.S. FDA which can be used before radiation exposure to protect exposed individuals. Here we aimed to evaluate the therapeutic potential of an aqueous suspension of synthetic genistein nanoparticles (BIO 300) as a radioprotectant in a pilot efficacy study using a nonhuman primate model of total body irradiation. Eight rhesus macaques were divided into two groups; four received vehicle and four received BIO 300 Injectable Suspension 24 h before 5.8 Gy total-body irradiation. Survival, blood cell counts, blood chemistry, and clinical parameters were monitored over the 60 days of the study. Tissues were collected at necropsy 60 days post-irradiation or from animals that met unscheduled euthanasia criteria and subjected to histopathological analysis. Tissues analyzed included the duodenum, jejunum, ileum, sternum, lung, heart, liver, kidney, spleen, gut-associated lymphoid tissue, and urinary bladder. In this pilot study, all BIO 300 Injectable Suspension treated animals survived to day 60, while only 50% of the vehicle-treated animals survived. We found that BIO 300 Injectable Suspension did not mediate an improvement in blood cell counts (e.g., neutrophils, platelets, white blood cells). However, BIO 300 Injectable Suspension treated animals had a lower incidence of fever and febrile neutropenia, were able to better maintain their body weight post radiation exposure, and exhibited less anemia and faster recovery from anemia. Histopathological analysis revealed that BIO 300-treated animals had less irradiation-induced damage to the sternum and other tissues compared to vehicle controls. BIO 300's mechanism of action is complex and protection against irradiation is attainable without much improvement in the complete blood count (CBC) profile. BIO 300's mechanism for radioprotection involves multiple biological pathways and systems.

Illuminating Pathways to Dynamic Nanotribology: Light-Mediated Active Control of Interfacial Friction with Nanosuspensions.

Active control of nanotribological properties is a challenge. Materials responsive to external stimuli may catalyze this paradigm shift. Recently, the nanofriction of a thin film is modulated by light, ushering in phototribology. This frontier is expanded here, by investigating photoactive nanoparticles in lubricants to confer similar functionality to passive surfaces. Quartz-crystal microbalance (QCM) is employed to assess the phototribological behavior of aqueous suspensions of titanium dioxide nanoparticles. A comparison of dark and illuminated conditions provides the first demonstration of tuning the interfacial friction in solid-nanosuspension interfaces by light. Cyclic tests reveal reversible transitions between higher (dark) and lower friction (illuminated) regimes. These transitions are underpinned by transient states with surface charge variations, as confirmed by Zeta potential measurements. The accumulated surface charge increases repulsion within the system and favors sliding. Upon cessation of illumination, the system returns to its prior equilibrium state. These findings impact not only nanotribology but nanofluidics and nanorheology. Furthermore, the results underscore the need to consider light-induced effects in other scenarios, including the calculation of activity coefficients of photoactive suspensions. This multifaceted study introduces a new dimension to in operando frictional tuning, beckoning a myriad of applications and fundamental insights at the nanoscale.

Effect of Different Levels of Aqueous Suspension of Bentonite Nanoparticles on Performance and Carcass Characteristics of Broiler Chickens

Effect of Different Levels of Aqueous Suspension of Bentonite Nanoparticles on Performance and Carcass Characteristics of Broiler Chickens

Evaluation of the application of suspensions of iron oxide magnetic nanoparticles functionalized with quaternized chitosan and phosphates on yellow maize and chili pepper plants

We have applied aqueous suspensions of magnetite-maghemite nanoparticles functionalized with quaternized chitosan and phosphate groups on yellow maize (Zea Mays) and chili pepper (Capsicum annuum) plants, at greenhouse conditions, to evaluate if any beneficial or adverse effects are produced by these nanocomposites in the development of these kind of plants at morphological and physiological level. Phytotoxicity assays with yellow maize seeds showed excellent germination percentages in all treatments evaluated, as well as increasing indicators of biomass and root length of germinated seeds for suspensions of nanoparticles with iron contents up to 50 ppm. Suspensions of nanoparticles with iron contents higher than 50 ppm led to decreasing indicators of biomass and root length of germinated seeds compared to lower iron contents. Iron contents of 100 ppm showed indicators lower than those of the control, suggesting phytotoxic effect of these nanocomposites for iron contents above 100 ppm. Measurements of morphological and physiological parameters of plants of both crops in greenhouse conditions, treated with suspensions of nanoparticles with iron-phosphorus contents of 25 − 3, 35 − 4 and 45 − 5 ppm, commercial fertilizer as positive control and tap water as a negative control did not evidence any phytotoxic or beneficial effect. The results suggest that, although these nanocomposites did not have a noticeable effect as vehicles of micro and macro nutrients as iron and phosphorus in the evaluated plants, they did not produce phytotoxic effects on them at the morphological and physiological level for iron contents less than 50 ppm, as they showed adequate growth and development.

Field-induced macroscopic flow of a dilute self-assembling magnetic colloid under rotating magnetic fields

Flow generation by colloidal motors activated by external stimuli is an important issue for active matter physics and several nanotechnological or biomedical applications. For instance, flow recirculation generated by rotating magnetic self-assemblies allows effective ‘pumping’ of a thrombolytic drug towards a blood clot along a blocked vessel. However, the physics of the flow generation in this case remains still poorly explored. This study is focused on the generation of a recirculation flow of a magnetic colloid (aqueous suspension of iron oxide nanoparticles with partially screened electrostatic repulsion) within a closed microfluidic channel via application of an external rotating magnetic field. The colloid undergoes reversible phase separation manifested through the appearance of micron-sized elongated aggregates. They synchronously rotate with the magnetic field and can generate macroscopic flows only in the presence of gradients of the aggregate concentration across the channel induced by superposition of a weak magnetic field gradient to the homogeneous rotating field. We achieve recirculation flows with a characteristic speed ${\sim} 5{-}8\;{\rm \mu}\textrm{m}\;{\textrm{s}^{ - \textrm{1}}}$ at low magnetic field amplitude and frequency ( ${H_0} \approx 3{-}10\;\textrm{kA}\;{\textrm{m}^{ - 1}}$ , ${f = 5{-}15\ \textrm{Hz}}$ ) at low nanoparticle volume fraction ${\varphi _p} = (1.6{-}3.2) \times {10^{ - 3}}$ . The concentration and velocity profiles have been assessed experimentally through particle tracking and particle image velocimetry, and have also been computed using the hydrodynamic diffusion approach coupled with the momentum balance equation with a magnetic torque term. The model correctly reproduces the shape of the experimental concentration and velocity fields and explains complex behaviours of the average recirculation speed as a function of governing parameters ( ${H_0}$ , f, ${\varphi _p}$ , channel size).

Colloidal Self-Assembly of Silver Nanoparticle Clusters for Optical Metasurfaces.

Optical metasurfaces are two-dimensional assemblies of nanoscale optical resonators and could constitute the next generation of ultrathin optical components. The development of methods to manufacture these nanostructures on a large scale is still a challenge, while most performance demonstrations were obtained with lithographically fabricated metasurfaces that are restricted to small scales. Self-assembly fabrication routes are promising alternatives and have been used to produce original nanoresonators. Reports of self-assembled metasurface fabrication, however, are still scarce. Here, we show that an emulsion-based formulation approach can be used both for the fabrication of complex colloidal resonators, presenting a strong interaction with light, in particular due to simultaneous magnetic and electric modes of resonance, and for their deposition in homogeneous films. This fabrication technique involves emulsification of an aqueous suspension of silver nanoparticles in an oil phase, followed by controlled drying of the emulsion, and produces silver colloidal clusters. We show that the drying process can be controlled in a liquid emulsion, producing a metafluid, as well as in a sedimented emulsion, producing a metasurface. The structural control of the synthesized colloidal clusters is demonstrated with electron microscopy and X-ray scattering techniques. Using a polarization-resolved multiangle light scattering setup in the visible wavelength range, we conduct a comprehensive angular and spectroscopic study of the optical resonant scattering of the nanoresonators in a metafluid and show that they present strong optical magnetic resonances and directional forward-scattering patterns, with scattering efficiencies of up to 4. The metasurfaces consist of homogeneous films, of variable surface density, of colloidal clusters that have the same extinction properties on the surface and in the fluid. This experimental approach allows for large-scale production of metasurfaces.

Green Synthesis of Sulphur Nanoparticles Using Azadirachta indica (Neem Leaf) and Its Characterization

Nanoscience has found various applications in different biomedical fields. The synthesis of nanoparticles (NPs) has become a vast area of research due to its potential applications. These particles can be prepared by different chemical, physical and biological approaches. In recent years, green synthesis of NPs using plant extracts has gained much interest due to non-toxicity and very low cost of synthesis. The plant extracts act both as reducing or stabilizing agent as well as capping agent. Neem (Azadirachta indica A. Juss) is a well-known medicinal plant and has been studied for the biosynthesis of NPs. A. indica has various phytochemicals identified that can reduce the metal ions. The bio reduction of NPs from neem extract is an eco-friendly, low cost and green synthesis method. These NPs are reported to exhibit good antimicrobial, mainly antibacterial activity. NPs was characterized by Dynamic Light Scattering (DLS) for particle size, particle size distribution, poly- dispersity index, zeta potential, UV visible spectrophotometer and Fourier-Transform Infrared Spectroscopy (FT-IR) for functional characteristics. Dynamic light scattering measurements for particle size (nm) and Polydispersity Index showed that the particle size was in the range of 35-40 nm with Polydispersity Index of 0.280-0.290, it is the mid-range value and indicating that the particles were in disperse form in aqueous suspension. From the analysis, the zeta potential value was found to be (-5.77 mV), revealing the better stability of synthesized sulphur nanoparticles in aqueous suspension. The FT-IR spectrum showed characteristic absorption of wavenumber from 3384.73 cm-1 and 533.56 cm-1. The absorption spectra of UV-visible spectrophotometer in between the range of 200-800 nm.

Comparative Study of Photothermal Conversion Efficiency in Aqueous Suspensions of Silicon and Titanium Nitride Nanoparticles for Biomedical Applications

Comparative Study of Photothermal Conversion Efficiency in Aqueous Suspensions of Silicon and Titanium Nitride Nanoparticles for Biomedical Applications

Nanocarrier of α-Tocopheryl Succinate Based on a Copolymer Derivative of (4,7-dichloroquinolin-2-yl)methanol and Its Cytotoxicity against a Breast Cancer Cell Line.

In order to improve the water solubility and, therefore, bioavailability and therapeutic activity of anticancer hydrophobic drug α-tocopherol succinate (α-TOS), in this work, copolymers were synthesized via free radicals from QMES (1-[4,7-dichloroquinolin-2-ylmethyl]-4-methacryloyloxyethyl succinate) and VP (N-vinyl-2-pirrolidone) using different molar ratios, and were used to nanoencapsulate and deliver α-TOS into cancer cells MCF-7. QMES monomer was chosen because the QMES pendant group in the polymer tends to hydrolyze to form free 4,7-dichloro-2-quinolinemethanol (QOH), which also, like α-TOS, exhibit anti-proliferative effects on cancerous cells. From the QMES-VP 30:70 (QMES-30) and 40:60 (QMES-40) copolymers obtained, it was possible to prepare aqueous suspensions of empty nanoparticles (NPs) loaded with α-TOS by nanoprecipitation. The diameter and encapsulation efficiency (%EE) of the QMES-30 NPs loaded with α-TOS were 128.6 nm and 52%; while for the QMES-40 NPs loaded with α-TOS, they were 148.8 nm and 65%. The results of the AlamarBlue assay at 72 h of treatment show that empty QMES-30 NPs (without α-TOS) produced a marked cytotoxic effect on MCF-7 breast cancer cells, corresponding to an IC50 value of 0.043 mg mL-1, and importantly, they did not exhibit cytotoxicity against healthy HUVEC cells. Furthermore, NP-QMES-40 loaded with α-TOS were cytotoxic with an IC50 value of 0.076 mg mL-1, demonstrating a progressive release of α-TOS; however, the latter nanoparticles were also cytotoxic to healthy cells in the range of the assayed concentrations. These results contribute to the search for a new polymeric nanocarrier of QOH, α-TOS or other hydrophobic drugs for the treatment of cancer or others diseases treatable with these drugs.

Ubiquitous fullerenes: A detection of C60 and C70 under sonolysis of aqueous graphite colloidal suspensions

For the first time, the molecular bands of the C2 species were detected in the single-bubble sonoluminescence spectra of aqueous colloidal suspensions of graphite nanoparticles (≤ 50 nm) obtained by ultrasonic dispergation upon multi-bubble sonolysis. The registration of these bands indicates that graphite nanoparticles enter the moving cavitation bubble together with solution microdroplets, where they are decomposed in the nonequilibrium plasma that occurs during ultrasonic vibrations into small fragments, including C2 radicals. Based on the conventional mechanism for the formation of fullerenes at the arc-discharge synthesis, starting from C2, under plasma conditions, we suggest that these framework molecules are synthesized in a cavitation bubble during single-bubble sonolysis of graphite nanoparticles. Indeed, the presence of the C60 and C70 fullerenes was registered in the accumulated sonolysis products of samples of suspensions of graphite nanoparticles with the chromatographic and mass-spectrometric techniques.

Aqueous Suspension of Porous SiO<sub>2</sub> Nanoparticles, Containing 9,10-diphenylanthracene, in Agrophotonics

An aqueous colloidal suspension of porous silicon dioxide nanoparticles containing an organic phosphor 9,10-diphenylanthracene was obtained by ultrasonic dispersion. The average size of suspension nanoparticles is 15–25 nm. This suspension has a characteristic absorption spectrum for diphenylanthracene in the region from 345 to 420 nm and a photoluminescence spectrum in the region from 400 to 550 nm. The resulting suspension was used for irrigation when growing bulbous plants (lilies and gladiolus) under conditions of a short light period with additional lighting with LEDs-based phytolamps with red and blue spectra. It has been established that the use of this suspension with nanoparticles that enter plants as an artificial photosynthetic pigment accelerates the growth of bulbous plants by an average of 15–20% compared to control samples under the same lighting conditions.

In vitro germination and growth of maize and lettuce seeds exposed to iron oxide magnetic nanoparticles

Iron is a micronutrient essential for optimal plant development, nevertheless, due to their low solubility it is poorly available to plants, affecting many agronomically important crops. Nanofertilizers are nanoparticles that have been used as an alternative for the release of micro and macronutrients necessary for plant nutrition. Therefore, in this research we evaluated the effect of the application of aqueous suspensions of iron oxide (magnetite-maghemite) nanoparticles stabilized with chitosan on the germination and growth of Maize (Zea mays L.) and Lettuce (Lactuca sativa L.) plants at in vitro level. Preliminary results suggest that for aqueous nanoparticle suspensions with iron contents below 50 ppm there is no evidence of negative effects on the seed germination process and on the growth of maize seedlings. Similarly, it was determined that there is no phytotoxic effect of the suspensions on Lettuce seeds.

Comparative Characterization of Aqueous Suspensions of Magnetic Iron Oxide Nanoparticles with Different Phase Compositions

Comparative Characterization of Aqueous Suspensions of Magnetic Iron Oxide Nanoparticles with Different Phase Compositions

Multi-screening analysis of single nanoparticles by the first multi-quadrupole ICPMS/MS

The recent expansion in the use of nanomaterials in various fields has led to a growing concern over their impacts on environmental systems. Accurate detection, quantification, characterization, and tracking of the nanoparticles are essential for assessing the ecological risks and their implications for environmental health. Inductively coupled plasma mass spectrometry (ICP-MS) operated in single-particle mode is an attractive analytical tool for quantification and sizing very small nanoparticles in aqueous suspensions. The ICP-MultiQuad-MS/MS can rapidly detect (including highly interfered elements) and characterize a large number of particles, determine size and size distributions, the particle number concentration in a sample, and the elemental mass concentration of both dissolved and particulate species. This paper provides the first systematic review of the ICP-MultiQuad-MS/MS to perform NPs analysis applied to different structures and compositions while simultaneously comparing them with the current state of the art of ICP-(CRC)-MS available. This study is done on composite nanomaterials with different shapes for elements with high sensitivity and no interference, like Au, Ag, and Pt, and elements with high interferences and lower sensitivity, like Fe, Si, and Ti.

In-silico investigation of intratumoural magnetic hyperthermia for breast cancer therapy using FePt or FeCrNbB magnetic nanoparticles

In this work, we conduct a numerical study on magnetic nanoparticle hyperthermia for the treatment of a breast tumour. The geometry of the problem is comprised of a deformed ellipsoidal tumour region, a healthy glandular tissue region, a fat tissue layer and a skin tissue layer. An aqueous suspension of magnetic nanoparticles (FeCrNbB or FePt) is directly injected into the breast tumour using a syringe. The perfusion of blood through the tissue regions is modelled using the Darcy-Brinkman-Forchheimer equation, and the shear-thinning behaviour of blood is described by the Carreau–Yasuda model. The transport and deposition of nanoparticles within the tissues, the temperature distribution during therapy, and the survival rates of healthy cells and cancer cells are also considered. The governing equations with their associated initial and boundary conditions are solved using the finite element method, and the solution algorithm developed in FreeFEM++ was validated against results from the existing literature. Subsequently, the influence of the nanoparticle solid volume fraction, injection time, and magnetic field amplitude and oscillation frequency on the velocity, temperature, nanoparticle concentration distribution, duration required for effective hyperthermia, and thermal damage to healthy tissues was examined. The numerical results reveal that the cell damage is greater in skin tissue than the healthy gland and fat tissues. For small injection time (tinj=0.4), the healthy gland tissue damage is greater for FePt nanoparticles than FeCrNbB nanoparticles. However, this trend is reversed for larger injection times (tinj=0.5, 0.6). For small magnetic field frequency (ω=5×104, 105), the maximum tissue temperature is higher with FePt nanoparticles than FeCrNbB nanoparticles, but a reversal in trend occurs for larger values of ω (ω=2×105). The findings show that the time duration required for effective magnetic hyperthermia and thermal damage to the healthy tissue regions is reduced with increased injected nanoparticle volume fraction, duration of nanoparticle injection, and the amplitude and frequency of the alternating magnetic field. Moreover, the effective hyperthermia duration and the healthy tissue damage are less for FePt nanoparticles than FeCrNbB nanoparticles.

The Relationship between Gelation Behavior and the Amount of Polymer Dose per Silica Surface Area of "Shake-Gels" Consisting of Silica Nanoparticles and Poly(Ethylene Oxide).

The understanding and control of the rheological behaviors of colloids and polymer mixtures is an important issue for scientific interests and industrial applications. Aqueous mixed suspensions of silica nanoparticles and poly(ethylene oxide) (PEO) under certain conditions are interesting systems called "shake-gels", whose states vary reversibly between sol-like and gel-like under repeated shaking and being left to stand. Previous studies have indicated that the amount of PEO dose per silica surface area (Cp) is a crucial parameter for the formation of shake-gels and the relaxation time from gel-like to sol-like states. However, the relationship between the gelation dynamics and the Cp values has not been fully investigated. To determine how the gelation dynamics are affected by the Cp, we measured the time taken for silica and PEO mixtures to gelate from the sol-like to gel-like states as a function of the Cp under different shear rates and flow types. Our results show that the gelation time decreased with increasing shear rates and depended on the Cp values. Moreover, the minimum gelation time was found around a certain Cp (=0.03 mg/m2) for the first time. The finding suggests that there is an optimum Cp value at which the bridging of silica nanoparticles using PEO is significant, and thus, the shake-gels and stable gel-like states are most likely to form.

Single-bubble sonoluminescence of aqueous suspensions of ZnS or Tb(acac)3·H2O nanoparticles

Aqueous suspensions of nanoparticles (below 50 nm in size) of ZnS or Tb(acac)3·H2O crystals were prepared by dispersion under multibubble sonolysis. Single-bubble sonoluminescence (SL) of these colloidal suspensions in an ultrasonic standing wave was found. For a ZnS suspension, the SL spectrum of a bubble moving at acoustic pressure pa = 1.29 bar, recorded with 12 nm resolution, exhibited a ZnS band with a maximum at 470 nm against the background of a wide continuum of bubble luminescence (200–700 nm). At a resolution of 1.2 nm, numerous lines of atomic (Zn, S) and ionic (S+, S2+, S3+) emitters were present in the 270–670 nm range. For a Tb(acac)3 suspension at 12 nm resolution, Tb3+ quasilines were detected at 488, 544, 585, and 618 nm (5D4 – 7Fj transitions, j = 6,5,4,3). At 1.2 nm resolution, no terbium atomic lines were found. The ZnS band and Tb3+ quasilines were present, although with a lower intensity (at a constant continuum intensity), in the SL spectra of suspensions for a stationary (pa = 1.07 bar) bubble. The atomic emitter lines for a stationary bubble were absent in the spectra of both suspensions. The ZnS band and Tb3+ quasilines in the SL spectra were similar to those in the photoluminescence (PL) spectra. However, the spectrum of a moving bubble in a Tb(acac)3 suspension differed from the PL spectrum in the relative intensities of the quasilines for some transitions. It was concluded that a non-equilibrium plasma was ignited in a stationary or moving bubble in suspensions under periodic compression of its gas content. This was the main source of luminescence during sonolysis, which was observed as thermal emission bursts in a plasma with a spectral continuum. In addition, sonophotoluminescence was generated as re-emission of the continuum luminescence partially absorbed by nanoparticles in suspensions; this occurred as flashes of ZnS or Tb3+ characteristic luminescence. Additionally, for a moving bubble, there was luminescence of these emitters associated with the entry of nanoparticles into the bubble and the collisional excitation of emitters in the plasma. In the case of a ZnS suspension, there was luminescence of atomic emitters (Zn, S) that formed upon decomposition and excitation of fragments of the initial emitter (ZnS) in a bubble plasma. The absence of a similar component in the SL spectrum of the Tb(acac)3 suspension may be attributable to low efficiency of the collisional excitation of terbium atoms, which were undoubtedly formed upon decomposition of nanoparticles in a bubble plasma. The emitters and mechanisms of the studied single-bubble sonoluminescence in colloidal suspensions were compared with those for the previously considered (J. Luminescence. 252 (2022) 119389) multibubble sonotriboluminescence in non-colloidal suspensions of ZnS or Tb(acac)3·H2O crystals.

Dynamics of the energy transfer involved in a diarylethene-perylenebisimide dyad: comparison between the molecule and the nanoparticle level.

Photochromic materials are widely used to achieve fluorescence photoswitching. Understanding the energy transfer processes occurring in these systems would be an advantage for their use and better optimization of their properties. In this scope, we studied a diarylethene-perylenebisimide (DAE-PBI) dyad that presents a bright red emission and a large ON-OFF contrast, both in solution and in an aqueous suspension of nanoparticles (NPs). Using ultrafast transient absorption spectroscopy, the excited state dynamics was characterized for this dyad in THF solution and compared to its behavior in NPs state. An efficient energy transfer process between the PBI fluorophore and the DAE photochromic unit in its closed form was demonstrated, occurring in a few hundreds of femtoseconds.

High-sensitivity NH3 gas sensor using pristine graphene doped with CuO nanoparticles

Ahighly sensitive and selective NH3 gas sensor was developedbased on single-layer pristine graphene doped with copper(II) oxide (CuO) nanoparticles of a specific size. High-quality single-layer graphene was grown using chemical vapor deposition. Approximately 15nm-sized CuO colloidal nanoparticles were fabricated by a microwave-assisted thermal method using copper acetate as the precursor, and dimethylformamide as the reducing and stabilizing agent. Pristine graphene was doped with an aqueous suspension of CuO nanoparticles at a coating speed of 1500rpm using a simple spin coater. CuO nanoparticle doping induces changes in the electronic properties of graphene; in particular, p-type doping significantly altered graphene resistivity in the presence of NH3 gas. Upon exposure of the pristine graphene surface to NH3 gas, NH3 reacted with O2-/ O-/ O2- species on the graphene surface and released electrons into graphene. This caused a change in the concentration of charge carriers in the valence channel of graphene and an increase in graphene resistivity, facilitating real-time NH3 monitoring with quick response and rapid recovery at 25 ℃ and ~ 55% relative humidity. Our results indicated that graphene doped with ~ 15nm-sized CuO nanoparticles can sense NH3 gas selectively with a resistivity response of ~ 83%. Moreover, the sensor exhibited good reusability, fast response (~ 19s), and rapid recovery (~ 277s) with a detection limit of 0.041ppm and a relative standard deviation of 0.76%.