Carbon dots-based fluorescent probes for sensitive and selective detection of iodide

Microwave assisted synthesis of doped carbon dots and their application as green and simple turn off-on fluorescent sensor for mercury (II) and iodide in environmental samples

A novel, green, facile and dual turn-off/on sensor for detection of Hg²⁺ and I^- was developed based on carbon dots. Carbon dots were synthesized from citric acid, urea, and thiourea by microwave-assisted method. The size of the carbon dots (CDs) was about 10 nm and the synthesized CDs showed a strong emission at 523 nm upon excitation at 416 nm. The fluorescence quantum yield was 19.2%. Mercury (II) quenched the fluorescence of carbon dots. This turn off sensor had linear response for Hg²⁺ over a concentration range from 0.1 to 20 µM with detection limit as low as 62 nM. The carbon dots/Hg²⁺ system was also used as a turn on sensor for detection of iodide. Linear concentration range for I^- was 0.1-10 µM with detection limit as low as 72 nM. The proposed method showed good sensitivity and selectivity with respect to interference ions. Finally, this system was successfully used for the detection of Hg²⁺ and I^- in tap, river and mineral waters and fish samples.

Optical sensing at the nanobiointerface of metal ion-optically-active nanocrystals

Optically-active nanocrystals (such as quantum dots and plasmonic noble metal nanoparticles) have received great attention due to their size-tunable optical properties. The indicator displacement assay (IDA) with optically-active nanocrystals has become a common practice for optical sensor development, since no sophisticated surface functionalization of nanoparticles is required. Among the IDA-based optical sensors, the use of metal ions as receptors seems to be attractive. Therefore, in this review, the research progress of optical sensing at the nanobiointerface of metal ion-optically-active nanocrystals has been summarized. In particular, metal ion-mediated selective recognition has been summarized here based on the classical Hard-Soft-Acid-Base (HSAB) principle, which has been seldom mentioned before. Most of the references were therefore categorized according to their located place based on the HSAB theory. Besides, several metal ion modulation strategies that were not related to the HSAB theory (e.g., redox modulation) were also included. Finally, due to the cross-talk of metal ions in selective recognition, we have also summarized sensor array development based on multiple metal ion receptors in IDA sensing with optically-active nanocrystals. Several interesting applications of the IDA sensing with metal ions as receptors and optically-active nanocrystals as indicators are presented, with specific emphasis on the design principles and photophysical mechanisms of these probes.

Carbon dots: emerging theranostic nanoarchitectures

Nanotechnology has gained significant interest from biomedical and analytical researchers in recent years. Carbon dots (C-dots), a new member of the carbon nanomaterial family, are spherical, nontoxic, biocompatible, and discrete particles less than 10nm in diameter. Research interest has focused on C-dots because of their ultra-compact nanosize, favorable biocompatibility, outstanding photoluminescence, superior electron transfer ability, and versatile surface engineering properties. C-dots show significant potential for use in cellular imaging, biosensing, targeted drug delivery, and other biomedical applications. Here we discuss C-dots, in terms of their physicochemical properties, fabrication techniques, toxicity issues, surface engineering and biomedical potential in drug delivery, targeting as well as bioimaging.

Nitrogen-doped carbon dot mediated fluorescence on–off assay for highly sensitive detection of I− and Br− ions

Nitrogen-doped carbon quantum dots (CDs) were synthesized in ethanol media by using citric acid (CA) as the carbon source and ethanediamine (EDA) as the nitrogen source.

Gram-Scale Synthesis and Kinetic Study of Bright Carbon Dots from Citric Acid and Citrus japonica via a Microwave-Assisted Method

Tracking dynamic cellular processes necessitates fluorescent materials that are photostable, biocompatible, water-soluble, nanosized, and nontoxic. In this study, highly fluorescent carbon dots (CDs) were produced from cheap and readily available sources, citric acid (CA) and Philippine citrus (Citrus japonica Thunb.) or calamansi juice (CJ) via a microwave-assisted method. A number of synthetic conditions were investigated systematically to optimize the preparation of CDs from CA and CJ. The formation mechanism, surface chemistry, and photoluminescence of CA-based CDs (CA-CDs) and CJ-based CDs (CJ-CDs) were evaluated after each stage of pyrolysis in detail using different characterization techniques, such as dynamic light scattering, diffusion-ordered spectroscopy, atomic force microscopy, ζ potential, X-ray diffraction, Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and absorption/emission spectroscopy. Gram-scale pyrolysis of CA with ethylenediamine (EDA) and CJ with EDA were carried out to provide CA-CDs (CA-18) within 18 min total pyrolysis time at 97% yield and CJ-CDs (CJ-14) within 14 min total pyrolysis time at 7% yield. Aqueous suspensions of CA-18 and CJ-14 CDs gave comparable bright blue luminescence at 462 nm. CA-CDs were shown to be nontoxic for mung beans up to 2 mg/mL, whereas CJ-CDs with higher surface negative charges inhibited growth above 0.5 mg/mL. This study demonstrates that bright CA- and CJ-CDs can be produced in gram-scale quantities using inexpensive methods. The size, amount, and extent of EDA incorporation are important in contributing to the formation of highly emissive particles.

Design of Carbon Dots Photoluminescence through Organo-Functional Silane Grafting for Solid-State Emitting Devices

Advanced optical applications of fluorescent carbon dots (C-dots) require highly integrated host-guest solid-state materials with a careful design of C-dots - matrix interface to control the optical response. We have developed a new synthesis based on the grafting of an organo-functional silane (3-glycidyloxypropyltrimethoxysilane, GPTMS) on amino-functionalized C-dots, which enables the fabrication of highly fluorescent organosilica-based hybrid organic-inorganic films through sol-gel process. The GPTMS grafting onto C-dots has been achieved via an epoxy-amine reaction under controlled conditions. Besides providing an efficient strategy to embed C-dots into a hybrid solid-state material, the modification of C-dots surface by GPTMS allows tuning their photoluminescence properties and gives rise to an additional, intense emission around 490 nm. Photoluminescence spectra reveal an interaction between C-dots surface and the polymeric chains which are locally formed by GPTMS polymerization. The present method is a step forward to the development of a surface modification technology aimed at controlling C-dots host-guest systems at the nanoscale.

Ultrasensitive and Selective Sensing of Selenium Using Nitrogen-Rich Ligand Interfaced Carbon Quantum Dots

This work reports a label-free, ultrasensitive, and selective optical chemosensory system for trace level detection of selenite (SeO₃^2-), the most toxic form of selenium, in water. The probe, i.e., carbon quantum dots (CQDs), is designed from citric acid by means of pyrolysis and is interfaced with a newly synthesized nitrogen-rich ligand to create a selective sensor platform (functionalized CQDs, fCQDs) for selenite in a water matrix. Spectral (NMR, UV-vis, photoluminescence, Raman, and Fourier transform infrared analyses) and structural (high-resolution transmission electron microscopy) characteristics of the designed new probe were investigated. The developed sensor exhibits high sensitivity (limit of detection = 0.1 ppb), a wide detection range (0.1-1000 ppb range, relative standard deviation: 3.2%), and high selectivity even in the presence of commonly interfering ions reported to date, including Cl^-, NO₃^-, NO₂^-, Br^-, F^-, As(V), As(III), Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺, Sr²⁺, Rb²⁺, Na⁺, Ca²⁺, Cs⁺, K⁺, Mg²⁺, Li⁺, NH₄⁺, Co²⁺, etc. The observed selectivity is due to designed ligand characteristics in terms of strong Se-N chemistry. Ultrafast spectroscopic analysis of the fCQDs in the absence and presence of selenite was studied to understand the sensing mechanism. The sensor was successfully exemplified for real water samples and exhibits comparative performance to conventional ion channel chromatography as well as flame atomic absorption spectroscopy for selenite analysis. The promising results pave ways for realization of a field deployable device based upon a developed probe for selenite quantification in water.

A "Turn-On" thiol functionalized fluorescent carbon quantum dot based chemosensory system for arsenite detection

Carbon quantum dots (CQDs) have emerged out as promising fluorescent probes for hazardous heavy metals detection in recent past. In this study, water soluble CQDs were synthesized by facile microwave pyrolysis of citric acid & cysteamine, and functionalized with ditheritheritol to impart thiol functionalities at surface for selective detection of toxic arsenite in water. Microscopic analysis reveals that the synthesized CQDs are of uniform size (diameter ∼5nm) and confirmed to have surface SH groups by FT-IR. The functionalized probe is then demonstrated for arsenite detection in water by "Turn-On" read out mechanism, which reduces the possibility of false positive signals associated with "turn off' probes reported earlier. The blue luminescent functionalized CQDs exhibit increase in fluorescence intensity on arsenite addition in 5-100ppb wide detection range. The probe can be used for sensitive detection of arsenite in environmental water to a theoretical detection limit (3s) of 0.086ppb (R²=0.9547) with good reproducibility at 2.6% relative standard deviation. The presented reliable, sensitive, rapid fCQDs probe demonstrated to exhibit high selectivity towards arsenite and exemplified for real water samples as well. The analytical performance of the presented probe is comparable to existing organic & semiconductor based optical probes.

Development of a robust, fast screening method for the potentiometric determination of iodide in urine and salt samples

In this work, a potentiometric flow injection method is described for the fast bi-parametric determination of iodide and iodate in urine and salt samples. The developed methodology aimed for iodine speciation with a potentially portable system (running on batteries). The iodate reduction to iodide was effectively attained in line within the same manifold. The iodide determination was accomplished in the dynamic range of 2.50×10^-6-1.00×10^-3M and the total iodine dynamic range, resulted from iodide plus iodate, was 3.50×10^-6-2.00×10^-3M. The calculated limits of detection were 1.39×10^-6M and 1.77×10^-6M for iodide and iodate, respectively. A determination rate of 21h^-1 for the bi-parametric iodide and iodate determination was obtained for sample injection. The urine samples (RSD <5.8% for iodide and RSD <7.0% for iodate) results were in agreement with those obtained by the classic Sandell-Kolthoff reaction colorimetric reference procedure (RD <7.0%) and standard samples from Centers for Disease Control and Prevention, Atlanta, USA (CDC) international inter-laboratory EQUIP program. The developed flow method was also successfully applied to the iodide and iodate determination in salt samples (RSD <3.1% for iodate and iodide), with comparable results to conventional procedures. No significant interferences were observed interference percentage <9% for both determinations.

A Nanosystem Capable of Releasing a Photosensitizer Bioprecursor under Two-Photon Irradiation for Photodynamic Therapy

The applications of photodynamic therapy (PDT) are usually limited by photosensitizers' side effects and singlet oxygen's short half-life. Herein, a mitochondria-targeted nanosystem is demonstrated to enhance the PDT efficacy by releasing a bio-precursor of photosensitizer under two-photon irradiation. A phototriggerable coumarin derivative is first synthesized by linking 5-aminolevulinic acid (5-ALA, the bio-precursor) to coumarin; and the nanosystem (CD-ALA-TPP) is then fabricated by covalently incorporating this coumarin derivative and a mitochondria-targeting compound triphenylphosphonium (TPP) onto carbon dots (CDs). Upon cellular internalization, the nanosystem preferentially accumulates in mitochondria; and under one- or two-photon irradiation, it releases 5-ALA molecules that are then metabolized into protoporphyrin IX in mitochondria through a series of biosynthesis processes. The subsequent red light irradiation induces this endogenously synthesized photosensitizer to generate singlet oxygen, thereby causing oxidant damage to mitochondria and then the apoptosis of the cells. Analysis via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays indicate that the novel PDT system exhibits enhanced cytotoxicity toward cancer cells. This study may offer a new strategy for designing PDT systems with high efficacy and low side effects.

An overview of nanoparticles commonly used in fluorescent bioimaging

This article gives an overview of the various kinds of nanoparticles (NPs) that are widely used for purposes of fluorescent imaging, mainly of cells and tissues. Following an introduction and a discussion of merits of fluorescent NPs compared to molecular fluorophores, labels and probes, the article assesses the kinds and specific features of nanomaterials often used in bioimaging. These include fluorescently doped silicas and sol-gels, hydrophilic polymers (hydrogels), hydrophobic organic polymers, semiconducting polymer dots, quantum dots, carbon dots, other carbonaceous nanomaterials, upconversion NPs, noble metal NPs (mainly gold and silver), various other nanomaterials, and dendrimers. Another section covers coatings and methods for surface modification of NPs. Specific examples on the use of nanoparticles in (a) plain fluorescence imaging of cells, (b) targeted imaging, (c) imaging of chemical species, and (d) imaging of temperature are given next. A final section covers aspects of multimodal imaging (such as fluorescence/nmr), imaging combined with drug and gene delivery, or imaging combined with therapy or diagnosis. The electronic supplementary information (ESI) gives specific examples for materials and methods used in imaging, sensing, multimodal imaging and theranostics such as imaging combined with drug delivery or photodynamic therapy. The article contains 273 references in the main part, and 157 references in the ESI.

Carbon dots as fluorescent probe for "off-on" Detecting sodium dodecyl-benzenesulfonate in aqueous solution

In this paper, we propose an "off-on" approach for the detection of sodium dodecyl-benzenesulfonate (SDBS) using carbon dots (CDs) as fluorescent probe. We firstly demonstrated that the fluorescence of CDs decreased apparently in the presence of ruthenium (Ru), and the system was thus "turn-off". The resulting CDs-Ru system was found to be sensitive to SDBS, SDBS not only serves to shelter the CDs effectively from being quenched, but also to reverse the quenching and restore the fluorescence due to its ability to remove Ru from the surface of CDs (turn-on). An eco-friendly, simple and sensitive platform for the detection of SDBS based on the CDs-Ru probes has been proposed. After the experimental conditions were optimized, the linear range for detection SDBS was 0.10-7.50 μg/mL, with correlation coefficient (r) 0.9988, detection limit was 0.033 μg/mL (3σ). This method is facile, rapid, low cost, environment-friendly, and possesses the potential for practical application.

A FRET fluorescent nanosensor based on carbon dots for ratiometric detection of Fe3+ in aqueous solution

A highly selective and sensitive FRET ratiometric fluorescent nanosensor has been developed for detecting Fe³⁺ in aqueous solution and on test papers. It works based on a Fe³⁺-triggered FRET process between CDs and ring-opened rhodamine 6G.

Paper carbon dot based fluorescence sensor for distinction of organic and inorganic sulphur in analytes

In this work a paper carbon dot (PCDs) based fluorescence sensor was developed which can distinguish between the organic and inorganic sulphur in analytes.

Synthesis of “amphiphilic” carbon dots and their application for the analysis of iodine species (I2, I− and IO3−) in highly saline water

In this work, “amphiphilic” carbon dots (A-CDs) with a strong green fluorescence were synthesized by a simple and green method at room temperature, and the synthesized A-CDs could be used for the analysis of iodine species (I₂, I⁻ and IO₃⁻) in highly saline water.

Intrinsic peroxidase-like activity and the catalytic mechanism of gold@carbon dots nanocomposites

The mechanism of AuNPs@CDs as nano-enzyme catalysing the oxidation of TMB in the presence of H₂O₂.

Fe(3+)-functionalized carbon quantum dots: A facile preparation strategy and detection for ascorbic acid in rat brain microdialysates

This study reports an Fe(3+)-functionalized carbon quantum dots (Fe(3+)-functionalized CQDs) for the highly sensitive and selective detection of ascorbic acid (AA) in rat brain microdialysates based on the specific redox reaction between iron(III) ions and AA. The carbon quantum dots (CQDs) were synthesized by one-step pyrolysis of a small organic molecules i.e. tris(hydroxymethyl)aminomethane (Tris). Fe(3+) can tightly chelate to the surface of CQDs by the hydroxyl group to form Fe(3+)-functionalized CQDs while the fluorescence of CQDs can be effectively quenched by Fe(3+) via Fluorescence resonance energy transfer (FRET). The fluorescence of the Fe(3+)-functionalized CQDs can be sensitively turned on by AA to give an "on-off-on" fluorescence response through the oxidation-reduction between Fe(3+) and AA since the produced Fe(2+) has much lower chelating ability to CQDs and the fluorescence of CQDs can be restored. This Fe(3+)-functionalized CQDs based nanoprobe shows high selective and sensitive response in the concentration of AA ranging from 0.1 μM to 50 μM with the detection limit as lower as 9.1 nM, which is lower than other assays. Finally, the proposed fluorescent probe was successfully applied to direct analysis of AA in biological fluids, i.e. rat brain microdialysates, and may pave a new route to the design of effective carbon quantum dots-based fluorescence probes for other bioassay.

Fluorescent carbon dot-molecular salt hydrogels

We report the incorporation of functionalised carbon nanodots within a low molecular weight salt hydrogel enhancing the gelation and fluorescence properties of both the gel and carbon nanomaterial.

The incorporation of functionalised carbon nanodots within a novel low molecular weight salt hydrogel derived from 5-aminosalicylic acid is reported. The carbon dots result in markedly enhanced gelation properties, while inclusion within the hydrophobic gel results in a dramatic fluorescence enhancement for the carbon nanomaterials. The resulting hybrid CD gels exhibit a useful sensor response for heavy metal ions, particularly Pb²⁺.

Thymine Functionalized Graphene Oxide for Fluorescence "Turn-off-on" Sensing of Hg2+ and I- in Aqueous Medium

Selective detection of either mercury (Hg2+) or iodide (I-) ion using fluorescence turn-on or turn-off processes is an important area of research. In spite of intensive research, simultaneous detection of both mercury and iodide using fluorescence turn-off-on processes, high sensitivity and theoretical support concerning the mechanisms are still lacking. In the present work, graphene oxide is functionalized by thymine to realize simultaneous detection of both Hg2+ and I- selectively using fluorescence turn-off-on mechanism. Ultra high sensitivity to the extent of ppb level exploiting large surface area of graphene is achieved. DFT calculations also assist to realize the detailed mechanisms involving this PL quenching and also its regain during sensing of these ions in aqueous solution.

Synthesis of highly photoluminescent carbon dots via citric acid and Tris for iron(III) ions sensors and bioimaging

In this work, high quantum yield and strong photoluminescent carbon quantum dots (C-QDs) are successfully synthesized via a facile and green hydrothermal method using citric acid and Tris as precursors. The as-synthesized C-QDs with a quantum yield (QY) as high as 52% were characterized by UV, FT-IR, TEM, XPS and fluorescence spectroscope. TEM results show that C-QDs are mono-dispersed spherical particles and the diameter distribution of C-QDs is 2.8±1.1 nm. The extraordinary photoluminescent properties and low cytotoxicity of C-QDs were obtained through optical property characterization and cytotoxicity assay. In addition, we found that the as-prepared C-QDs had a high affinity for Fe(3+) ions and the response toward Fe(3+) ions was highly linear (R(2)=0.997) over the concentration range from 2 to 50 μM, which could provide an effective platform for portable detection of Fe(3+) ions. Also, it is demonstrated that the photoluminescent C-QDs display hypotoxicity and are biocompatible for use as biosensors in living cells.

Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications

The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications.

Recent applications of carbon nanomaterials in fluorescence biosensing and bioimaging

A review of recent applications of carbon nanomaterials in fluorescence biosensing and bioimaging.

Carbon quantum dots and their applications

This review covers the progress in the research and development of carbon quantum dots and their applications in chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis.

Synthesis of a carbon-dot-based photoluminescent probe for selective and ultrasensitive detection of Hg2+ in water and living cells

Nitrogen and sulphur co-doped carbon dots with high PL quantum yield and photostability have been synthesized by a simple hydrothermal synthesis and successfully used for bioimaging of Hg²⁺ in living cells.

Recent developments in carbon nanomaterial sensors

The structural diversity of carbon nanomaterials provides an array of unique electronic, magnetic and optical properties, which when combined with their robust chemistry and ease of manipulation, makes them attractive candidates for sensor applications. In this review recent developments in the use of carbon nanoparticles and nanostructures as sensors and biosensors are explored.

Simultaneous determination of iodide and creatinine in human urine by flow analysis with an on-line sample treatment column

The first system suitable for large-scale screening of iodine deficiency in humans was developed. This is a step towards resolving the outstanding problems of sample preparation and 24 h urine collection.

Carbon nanodots prepared from o-phenylenediamine for sensing of Cu(2+) ions in cells

A simple hydrothermal method was applied to prepare carbon nanodots (C dots) from o-phenylenediamine (OPD). The C dots exhibit photoluminescence at 567 nm when excited at 420 nm. In the presence of Cu(2+) ions, the colour of C dots changes from yellow to orange, with an increased PL intensity as a result of the formation of Cu(OPD)2 complexes on the surfaces of C dots. The D-band to G-band ratios of C dots in the absence and presence of 80 nM Cu(2+) ions are 1.31 and 4.75, respectively. The C dots allow the detection of Cu(2+) ions with linearity over a concentration range of 2-80 nM, with a limit of detection of 1.8 nM at a signal-to-noise ratio of 3. The cell viability values of A549, MCF-10A, and MDA-MB-231 cells treated with 3 μg mL(-1) of C dots are all greater than 99%, showing their great biocompatibility. Having great water dispersibility, photostability, chemical stability (against NaCl up to 0.5 M), great selectivity, and biocompatibility, the C dots have been employed for the localization of Cu(2+) ions in the cancer cells (A549 cells) treated with 10 μM Cu(2+) ions.

β-Cyclodextrin and calix[4]arene-25,26,27,28-tetrol capped carbon dots for selective and sensitive detection of fluoride

In this work we have designed a novel system based on carbon dots prepared from chitosan gel capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol for sensitive and selective detection of fluoride ions in aqueous media. Fluorescent carbon dots prepared from chitosan gel when capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol results in quenching of its fluorescence intensity. Introduction of F(-) ions to carbon dots capped with β-cyclodextrin and calix[4]arene-25,26,27,28-tetrol system results in enhancement and restoration of fluorescence intensity leading to detection of F(-) ion. Minimum detection limit was determined to be ∼6.6 μM. The detection is selective as with other halide ions i.e. Cl(-), Br(-) and I(-) and hydroxyl ion (OH(-)), there is observed decrease of fluorescence intensity. A possible mechanism to justify the observation is also discussed in the paper.

Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots

Photoluminescent graphene quantum dots (GQDs) have received enormous attention because of their unique chemical, electronic and optical properties. Here a series of GQDs were synthesized under hydrothermal processes in order to investigate the formation process and optical properties of N-doped GQDs. Citric acid (CA) was used as a carbon precursor and self-assembled into sheet structure in a basic condition and formed N-free GQD graphite framework through intermolecular dehydrolysis reaction. N-doped GQDs were prepared using a series of N-containing bases such as urea. Detailed structural and property studies demonstrated the formation mechanism of N-doped GQDs for tunable optical emissions. Hydrothermal conditions promote formation of amide between –NH₂ and –COOH with the presence of amine in the reaction. The intramoleculur dehydrolysis between neighbour amide and COOH groups led to formation of pyrrolic N in the graphene framework. Further, the pyrrolic N transformed to graphite N under hydrothermal conditions. N-doping results in a great improvement of PL quantum yield (QY) of GQDs. By optimized reaction conditions, the highest PL QY (94%) of N-doped GQDs was obtained using CA as a carbon source and ethylene diamine as a N source. The obtained N-doped GQDs exhibit an excitation-independent blue emission with single exponential lifetime decay.

Gold-nanoparticles-modified cellulose membrane coupled with laser desorption/ionization mass spectrometry for detection of iodide in urine

We report an efficient method for the determination of iodide (I(-)) ions by using gold-iodide hybrid cluster ions on gold nanoparticles (Au NPs) modified mixed cellulose ester membrane (Au NPs-MCEM) by pulsed laser desorption/ionization mass spectrometry (LDI-MS). When I(-) ions were deposited and concentrated on the surfaces of Au NPs (32 nm) via strong Au(+)-I(-) interaction on the MECM, the Au NPs-MCEM was observed to function as an efficient surface-assisted LDI substrate with very low background noise. When pulsed laser radiation (355 nm) was applied, I(-) binding to Au NPs ions induced the enhancement of the desorption and ionization efficiency of gold-iodide hybrid cluster ions from the Au NPs surfaces. The reproducibility of the probe for both shot-to-shot and sample-to-sample (both less than 10%) ion production was also improved by the homogeneous nature of the substrate surface. Thus, it allows the accurate and precise quantification of I(-) ions in high-salinity real samples (i.e., edible salt samples and urine) at the nanomolar range. This novel LDI-MS approach provides a simple route for the high-speed analysis of I(-) ions with high sensitivity and selectivity in real biological samples.