Surface Of C-dots Research Articles

A proton-coupled electron transfer process from functionalized carbon dots to molecular substrates: the role of pH.

Multiple electron and proton transfers in nanomaterials pose significant demands and challenges across the various fields such as renewable energy, chemical processes, biological applications, and photophysics. In this context, pH-responsive functional group-enriched carbon dots (C-Dots) emerge as superior proton-coupled electron transfer (PCET) agents owing to the presence of multiple functional groups (-COOH, -NH2, and -OH) on the surface and redox-active sites in the core. Here, we elucidate the 2e-/2H+ transfer ability of carboxyl-enriched C-Dots (C-Dot-COOH) and amine-enriched C-Dots (C-Dot-NH2) with molecular 2e-/2H+ acceptor (benzoquinone, BQ) as a function of pKa, facilitated by the formation of new O-H bonds. The ground state and excited state pKa values of different functional groups on the surface of C-Dots are determined using steady-state absorbance and photoluminescence (PL) spectroscopy. The optical spectroscopy and electrochemical studies are employed to comprehend the influence of the surface and core of C-Dots on the proton and electron transfer processes as a function of pH. The cyclic voltammetry analysis reveals a standard Nernstian shift in E1/2 per pH unit of 30 mV, indicating that the functionalized C-Dots hold promise as candidates for the 2e-/2H+ transfer process. The calculated bond dissociation free energy (BDFE) of the electroactive O-H/N-H bonds provides a more nuanced and detailed understanding of PCET thermodynamic landscapes. These findings underscore the potential of nanoscale functionalized C-Dots for facilitating multiple PCET reactions in future energy technologies.

FACILE SYNTHESIS OF FLUORESCENT CARBON NANODOTS FROM SOURSOP PEEL AS A CARBON SOURCE FOR FERRIC METAL ION SENSOR

In this work, we present a simple fabrication process of carbon nanodots (C-dots) from soursop peel as a carbon source. The aims of this research are to analyze the optical properties of the C-dots and to synthesize the C-dots as sensors for detecttion of ferric (Fe 3+ ) ions. The optical properties of the prepared C-dots were characterized by spectrophotometry of UV−Vis, photoluminescence, and FTIR. Whereas the synthesis process was conducted by blending with FeCl3H2O. The prepared C-dots emitted blue emission color. They had an absorption peak at 278 nm corresponding to the characteristic of π →π* transition. When excited by an excitation wavelength of 340 nm, the PL peak at 430 nm corresponded to their blue emission color. Thus, the appearance of the O-H and C=O bonds in the FTIR spectrum demonstrated that the surface of C-dots was coated by hydroxyl and carbonyl groups, respectively. Interaction between C–dots and Fe 3+ ion, investigated over quenching of the PL intensity of the C-dots after each addition of Fe 3+ ion, demonstrated that the C-dots can be applied as a sensor for Fe 3+ ion detection. The value of the limit of detection and limit of quantification from Fe 3+ ion were determined to be 0.26 mM, These research results could, therefore, pave a large opportunity to explore C-dots from soursop peel for detection of Fe 3+ ion in biosensing, in vivo bioimaging, biomedicine, light-emitting diodes, and so on.

Carboxyl groups on carbon nanodots as co-reactant sites for anodic electrochemiluminescence of tris(2,2-bipyridine)ruthenium(II)

Carbon nanodots (C-dots) with good biocompatibility have been extensively utilized as co-reactants for electrochemiluminescence (ECL) of the tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)32+) system. However, the ECL intensity of this system is still relatively low and the mechanism of C-dots as co-reactants remains unclear, which greatly limits its further application in bio-analysis. In this work, we revealed that the carboxyl groups on C-dots are co-reactant sites for Ru(bpy)32+ ECL by systematically investigating the contribution of carboxyl, hydroxyl and carbonyl groups on the surface of C-dots to the ECL intensity. Further treatment with hydrogen peroxide to increase the carboxyl-group content on C-dots resulted in a 10-fold increase in ECL intensity over the original Ru(bpy)32+/C-dots system. This work provides new insights for the rational design of ECL systems with C-dots as co-reactants and offers new chances for further applications of C-dots in the field of ECL.

Development of a novel C-dots conductometric sensor for NO sensing

Carbon dots (CDs, C-dots) obtained from waste produced during the production of olive oil in Calabria (Italy) have been investigated as a gas sensing material for the sensitive and selective detection of nitric oxide (NO) in air. The obtained CDs were characterized by XPS, FT-IR and ATR-FTIR. CDs were deposited to yield a sensitive layer on a conductometric platform and tested for gas sensing, showing promising characteristics for the selective monitoring of NO in air. The response of CDs composite to NO was 1.5 @ 1250 ppm and the response and recovery times amounted to 90 and 200 s, respectively. The sensing behavior of C-dots prepared using olive waste from a different geographic location (Puglia, Italy) was also reported and compared. It has been found that the sensing behavior of the two different materials based sensors investigated towards nitrogen oxides (NO and NO2) was completely different. On the one hand, the former exhibited selectivity towards NO. On the other, the latter showed prominent selectivity towards NO2. This behavior can be ascribed to the different functional groups exposed on the C-dots surface undergoing non-covalent interactions with a marked specificity of the hydroxyl and ethers moieties for NO and NO2, respectively.

Resveratrol Carbon Dots Disrupt Mitochondrial Function in Cancer Cells.

Resveratrol, a natural polyphenol, exhibits beneficial health properties and has been touted as a potential anti-tumor agent. Here, we demonstrate potent anti-cancer effects of carbon dots (C-dots) synthesized from resveratrol. The mild synthesis conditions retained resveratrol functional moieties upon the carbon dots' (C-dots) surface, an important requisite for achieving specificity toward cancer cells and biological activities. Indeed, the disruptive effects of the resveratrol-C-dot were more pronounced in several cancer cell types compared to normal cells, underscoring targeting capabilities of the C-dots, a pertinent issue for the development of cancer therapeutics. In particular, we observed impairment of mitochondrial functionalities, including intracellular calcium release, inhibition of cytochrome-C oxidase enzyme activity, and mitochondrial membrane perturbation. Furthermore, the resveratrol C-dots were more potent than either resveratrol molecules alone, known anti-cancer polyphenolic agents such as curcumin and triphenylphosphonium, or C-dots prepared from different carbonaceous precursors. This study suggests that resveratrol-synthesized C-dots may have promising therapeutic potential as anti-cancer agents.

An ideal ratiometric fluorescent probe provided by the surface modification of carbon dots for the determination of Pb2+

Herein, carbon dots (Cdots) with a single green emission peak and no response to metal ions were converted to a high sensitive and selective ratiometric fluorescent probe for the detection of Pb2+ through a simple chemical surface modification with glutathione. The as-prepared modified Cdots show two emission peaks at a 170 nm distance (from 522 to 692 nm) that were excited with a single excitation wavelength (390 nm) and responded oppositely to Pb2+. This probe provided an ideal ratiometric fluorescent probe for the determination of Pb2+ in a linear concentration range of 10–700 nM with a detection limit of 2.7 nM. Theoretical calculations based on density functional theory (DFT) theory demonstrated that the surface modification of Cdots with glutathione forms new emitting centers on the surface of Cdots that were suppressed through a photo-induced electron transfer (PET) process from the sulfur lone pair electrons of the surface glutathione ligands. However, in the presence of Pb2+, chemical binding between the sulfide groups of surface glutathione ligands of neighboring Cdots and Pb2+ aggregated Cdots. Upon this complex formation, the involved PET process was stopped and subsequently a new emission peak at longer wavelengths appeared.

Study on optical properties of carbon nanodots by annealing of rice powder as a carbon source

In this work, we present the fabrication process and analyze the optical properties of carbon nanodots (C-dots) from rice powder taken from Kupang regency, East Nusa Tenggara Province. The rice powder was annealed at 400oC for 30 minutes to obtain a black powder. This sample (0.5 gram, 3 mL ethanol) was sonicated for an hour, and ethanol (10 mL) was added again for the centrifugation process at 1000 rpm for 20 minutes. Furthermore, the ethanol solution was filtered to realize C-dots. By irradiation with a UV lamp at 365 nm, C-dots emitted blue emission color, and they have absorption peaks at a wavelength of 276 nm. Upon excitation wavelength (λexc) of 350 nm, their fluorescence (FL) spectrum range is from 360 to 650 nm with maxima FL intensity at 436 nm corresponding to blue emission color as well as high photostability. The appearance of O-H and C=O bonds indicates that the surface of C-dots was coated with hydroxyl and carbonyl groups. Therefore, the blue emission color and excellent photostability of these C-dots can pave a large opportunity to explore the C-dots from rice powder as a functional material in electronic devices such as sensors, light emitting diodes, and so on forth.

Carbon dots as Reactive Nitrogen Species nanosensors

Three sets of Carbon Dots (Cdots) were produced through the carbohydrates acid thermal decomposition method. These nanoparticles were functionalized with a polymer, known for its biological compatibility: polyethylene glycol, PEG200, and folic acid, FA, a biomolecule associated with the reactive oxygen and nitrogen (ROS/RNS) savaging process, thus resulting CdotsPEG200, CdotsPEG200FA and CdotsFA. These nanoparticles were tested as nitric oxide radical (NO·) sensors and it was determined that CdotsPEG200FA and CdotsFA fluorescence intensity was quenched by the presence of this radical specie. Moreover, according to the Benesi-Hilderbrand plot, the nanoparticles have a high affinity towards the analyte and this interaction is consistent with a 1:1 stoichiometry, through an independent mechanism. The Stern-Volmer constant, obtained for both sensing systems, is compatible with the formation of stable complexes (static quenching) between the Folic Acid residues on the Cdots surface and NO·. The detection and quantification limits along with the sensitivity were calculated for both nanoparticles: DL (31.7 ± 0.02) x 10−9, QL (96.29 ± 0.01) x 10−9, Sensitivity (5.2 ± 0.5) x 109 M for CdotsFA and DL (83 ± 3) x 10−10, QL (251 ± 2) x 10−10, Sensitivity (8.4 ± 0.3) x 1010 M. These values are adequate for biological sensing and are quite competitive with other reported nanosensors for NO· detection and quantification.

Quantum yield optimization of carbon dots using response surface methodology and its application as control of Fe3+ion levels in drinking water

Early detection of heavy metals in drinking water is a fundamental step that must be taken to prevent adverse effects on health. This research aims to develop a heavy metal ion detector by utilizing the fluorescence properties of carbon dots. Cdots were synthesized using the microwave irradiation method based on the central composite design: urea mass 0.31–3.68 gr; reactor power 200–1000 W; synthesis time is 13–46 min, and the response is quantum yield. Material characterization includes PL, TEM, UV-VIS, XRD, and FTIR. The selectivity and sensitivity of Cdots as detectors were tested for Ag+, Bi3+, Ni2+, Al3+, Co2+, Pb2+, Fe3+, Zn2+, Zr4+, and Hg2+ ions at concentrations of 0–10 μM. The results showed that Cdots were successfully synthesized by fluorescent light green at 544 nm. An adequate response model is quadratic with the formulation QY = +58.36 + 10.41X1 + 14.06X2 +13.59X3–5.57X2X3–4.89X1 2−8.60X2 2–5.40X3 2. The best Cdots were obtained in the formulation of R9 (3 g, 800 W, 40 min), which resulted in a QY of 74.39%. The characteristics of Cdots are spherical, diameter 6.6 nm, the bandgap of 2.53 eV, and having an amorphous structure. The surface of Cdots contains various functional groups such as O–H, C–H, C=O, C–N, and C=C. In the heavy metal detection test, Cdots showed specific sensitivity to Fe3+ ions. The addition of Fe3+ concentration and the extinction of Cdots fluorescence intensity formed a linear correlation F0/F = 0.08894[Fe3+]+0.99391 (R2 = 0.99276). The detection ability of Cdots for Fe3+ ions reaches a concentration of 0.016 ppm, much lower than the regulatory threshold limit of SNI, WHO, and IBWA. The detection of Fe3+ ions in drinking water uses a fluorescence technique consistent with the SSA and ICP-OES. Based on these results, the fluorescence technique using Cdots can be an instrument for quality control of the final drinking water product.

PH-Dependent surface properties of N–Cdots obtained by the hydrothermal method with multicolored emissions

This study addresses the pH-dependent surface properties of hydrophilic nitrogen-doped carbon dots (N–Cdots) elaborated through a hydrothermal method. The samples were obtained using p-phenylenediamine and urea (N–CdotR), and citric acid and ammonium hydroxide (N–CdotB) as precursors, respectively. The structural and morphological properties of the N-Cdots were investigated using TEM, Raman spectroscopy and FTIR. The nanoparticles of both samples exhibited a large number of hydrophilic surface groups. Potentiometric and conductometric titrations were used to determine the pKs of the N–Cdots surface groups (pK1 = 3.4 and pK2 = 6.6 for N–CdotR; pK1 = 7.6 and pK2 = 9.9 for N–CdotB). Measurements of zeta potential and hydrodynamic diameter as a function of pH indicated that the charge modulation and colloidal stability of the N–Cdots are controlled mainly by amine and carboxyl groups in N–CdotR and carboxyl and phenolic groups in N–CdotB. The optical properties of the N–Cdots were characterized using UV-Vis spectroscopy. The photoluminescence results indicated that the acid-base behavior of the surface groups promotes changes in the energy emission states, with blue- and redshifts. Moreover, the N–Cdots presented significant quantum fluorescent yield (QY = 25% for N–CdotR and QY = 30% for N–CdotB) and good photostability. The whole of these results demonstrates that pH is a key parameter to monitor the colloidal stability and optical properties of N–Cdots as well as their potential technological applications.

Tailoring Multiple Porosities of Hierarchical ZSM‐5 Zeolites by Carbon Dots for High‐Performance Catalytic Transformation

AbstractA simple and high‐efficiency method is proposed to synthesize hierarchical ZSM‐5 zeolites with micropore and multistage mesopores by adopting water‐soluble carbon dots (CDots) with various size distributions, such as 1‐stage size distribution of CDots‐1 of around 23 nm, 2‐stage size distribution of CDots‐2 of 6 and 9 nm, 3‐stage size distribution of CDots‐3 of 5, 8, and 18 nm. The abundant OH and COOH groups on the surface of CDots provide high solubility in water. The characterization techniques confirmed that the dual‐porous h‐ZSM‐5 (MIcro–mEsopores) and multi‐porous h‐ZSM‐5 (MIcro–mEso–mEsopores), h‐ZSM‐5 (MIcro–mEso–mEso–mEsopores, M‐IEEE) catalysts are obtained. Notably, the hierarchical ZSM‐5(M‐IEEE) catalyst with micropore of 0.55 nm, two small mesopores of 4.8 and 7.4 nm, and one large mesopore of 17.5 nm show excellent catalytic performance with the highest 1,3,5‐triisopropylbenzene (TIPB) cracking conversion (97.3%) and high stability. Similarly, the h‐ZSM‐5(M‐IEEE) shows the high ethanol to olefins conversion (100%). The improved catalytic activity can be attributed to the more efficient diffusion of reactants and products in the crystals with the help of multistage mesopores, improved anti‐coking stability, combined with the effect of suitable acidity, and the increased accessibility of the acid sites.

Non-Newtonian Thermosensitive Nanofluid Based on Carbon Dots Functionalized with Ionic Liquids.

Non-Newtonian nanofluids present outstanding features in terms of energy transfer and conductivity with high application in numerous areas. In this work, non-Newtonian nanofluids based on carbon dots (Cdots) functionalized with ionic liquids (ILs) are developed. The nanofluids are produced using a simple, single-step method where the raw materials for the Cdots synthesis are glucose and waste biomass (chitin from crab shells). The use of ILs as both reaction media and functionalization molecules allows for the development of a new class of nanofluids, where the ILs on the Cdots surface represent the base-fluid. Here, the well-known benign IL 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and a novel home-made IL (1-tosylate-3-methyl-imidazolium triflate) [Tmi][Trif] are used. The nanofluids obtained from both substrates show, apart from high conductivity and viscosity, light absorption, and good wettability, an appealing thermal sensitivity behavior. This thermal sensitivity is preserved even when applied as thin films on glass slides and can be boosted using the surface plasmon resonance effect. The results reported demonstrate that the new Cdots/IL-based nanofluids constitute a versatile and cost-effective route for achieving high-performance thermosensitive non-Newtonian sustainable nanofluids with tremendous potential for the energy coatings sector and heat transfer film systems.

Polyvinyl alcohol and silver decorated carbon quantum-dots for new nano-composites with application electromagnetic interface (EMI) shielding

In this article, the marriage of (Ag@CDots) and PVA has been done via the solution casting approach for the electromagnetic shielding performance. Decoration of Ag on the CDots surface is performed by precipitation method in order to increase the conductivity of the nano-composite. The synergetic effect of nanofillers on the morphology, structure, mechanical, dielectric and electrical properties has been extensively studied. SEM analysis has displayed a high dispersion and an excellent adhesion of Ag@CDots in PVA template. The conductivity tends to increase, when Ag@CDots increased, to be 31.95 S/m at 8 wt.% of Ag@CDots due to formation of conductive path of Ag@CDots. Also, the dielectric constant increases with increasing Ag@CDots nano-particles due to formation of microcapacitors in the template of nano-composite. Young's modulus has dramatically increased up to 9.1 ± 0.71 GPa for 8 wt.% of Ag@CDots. Ag@CDots/PVA nano-composite displays the total shielding effectiveness (SET) of electromagnetic interface (EMI) of 56 dB at 8 GHz at thickness 1 mm, due to the equal contribution of EM reflection and absorption in the main mechanism of shielding effectiveness. Finally, the fine dispersion and the brilliant features harmonize together to make (Ag@CDots/PVA) nano-composites having a high total value of shielding (SET) and producing a shielding in X-band range about 99.9 % of electromagnetic radiation.

Double-pulse femtosecond laser ablation for synthesis of ultrasmall carbon nanodots

Carbon nanodots (C-dots) with ultrasmall size possessing large surface-to-volume ratio are expected to improve their performance in sensing and catalytic applications. Here, we present a simple strategy to synthesis ultrasmall C-dots using double-pulse femtosecond laser ablation in solution. The size of C-dots reaches minimum value of ∼1 nm when the delay between the pulses was approaching the electron-ion relaxation time. In this case, the mean sizes of C-dots in double-pulse ablation are even smaller than that obtained in single-pulse ablation with the same laser fluence due to the suppression of rarefaction wave by the shock wave created by the second pulse. Furthermore, abundant functional groups are created on the surface of C-dots in double-pulse ablation because of reheating the nascent ablated materials by the second pulse. These results demonstrate that the double-pulse technique is therefore an effective strategy beyond single-pulse ablation to synthesis ultrasmall C-dots with abundant surface functional groups as well as other nanoparticle for catalytic and sensing applications.

Photoluminescence Properties of Poly (Ethylene Glycol) Passivated Carbon Dots from Cassava Peels

<p>Carbon dots (C-dots) is a new type of luminescense nanoparticles that can be synthesized easily from natural sources, such as cassava peels. C-dots has been synthesized from cassava peels based green synthesis using low temperature. The surface of C-dots was passivated by poly(ethylene glycol) (PEG) with variations in volume from 0.5 ml, 1 ml, and 1.5 ml. Luminescense properties before and after passivasive with PEG characterized using photoluminescense (PL) and time resolved photoluminescence (TRPL) spectrophotometer. Peak wavelength spectrum of PL shows a red shift when 0.5 ml PEG was added. However, when the addition of PEG increases, peak wavelength spectrum of PL shows a blue shift. PL intensity decreased along with increasing of PEG volume. PL intensity influenced C-dots electron time decay linearly. C-dots electron time decay increased along with decreased of PL intensity. This results assigned potency that C-dots in water solution can be applied as bioimaging and metal ion and salt biosensing. however, it needs extra optical measurements to support our discovery.</p><p><strong>Keywords</strong>: cassava peels, C-dots, electron time decay, FL intensity, PEG</p>

Pesticide-derived bright chlorine-doped carbon dots for selective determination and intracellular imaging of Fe(III).

Inspired by the conversion from organics or biomass to fluorescent carbon dots (C-dots), the use of pesticide 4-chlorophenol (4-CP) as a precursor to prepare C-dots has been reported. The as-prepared chlorine-doped C-dots display a brightly blue emission at ∼445 nm with ∼22.8% quantum yield. Also, the surface of C-dots enriches functional groups, such as phenolic hydroxyl and carboxylic acid, etc., which can capture ferric ion (Fe(III)), resulting in the quenching of blue fluorescence of C-dots through an inner filter effect. The quantitative assay for Fe(III) was therefore realized by this probe with a 0.36 μM detection limit in the 0.6-25 μM concentration range. Most significantly, the cytotoxicity on Hela cells indicates the 4-CP-derived C-dots have a negligible cytotoxicity. The C-dots were applied in detection in environmental samples and imaging in Hela cells of Fe(III), demonstrating their good applicability, low toxicity and good biocompatibility, and providing an alterative approach to totally eliminate the harm of chlorophenols (CPs).

A composite consisting of bromine-doped carbon dots and ferric ions as a fluorescent probe for determination and intracellular imaging of phosphate.

A composite probe has been developed for fluorometric determination and imaging of phosphate in real water samples and in cells. The method is based on the use of weakly blue fluorescent bromine-doped carbon dots (C-dots) containing aromatic carbon-bromine groups and loaded with Fe3+ ions. The carboxy, phenolic hydroxy and aldehyde groups on the surface of the C-dots can coordinate with Fe3+ to form an adsorbed complex that reduces the blue fluorescence through an inner filter effect. If phosphate is added, it will capture Fe3+ on the surface of C-dots and restore fluorescence by ~88% via a displacement approach. The probe, best operated at excitation/emission maxima of 370/418nm, has a linear response in the 0.4 to 22μM phosphate concentration range and a 0.25μM of detection limit. The relative standard deviation (at a phosphate level of 8.0μM) is 3.6% (for n = 5). The method was applied to confocal imaging of phosphate in HeLa cells. Graphical abstractSchematic representation of the synthesis of bromine-doped carbon dots (C-dots) by a "one-step" approach. They are shown to be capable of (a) detecting phosphate in real water samples through the displacement approach, and (b) of imaging intracellular phosphate.

Biocompatible carbon dots derived from κ-carrageenan and phenyl boronic acid for dual modality sensing platform of sugar and its anti-diabetic drug release behavior.

Detection of sugar by enzymatic assay has been suffering from costly, time-taking, instable and denaturation of glucose oxidase. Recently, chemosensors that have affinity towards boronate became the hot topic in the domain of monosaccharide detection. In this work, a novel strategy was addressed to fabricate carbon dots (C-dots) from linear sulfated polysaccharides κ- carrageenan and phenyl boronic acid for nonenzymatic monosaccharide (glucose) detection. The boronic acid group anchored C-dots surface can form assembly by covalently bonded with the cis-diol moiety of the glucose which caused fluorescence quenching of the C-dots. The inert surface nature of the luminescent C-dots enables them to sense as low as 1.7 μM glucose without the interference of other biomolecules. The proposed sensing system was successfully applied for assay of glucose in blood serum. Interestingly, these C-dots were used as a nano vehicle for delivery of anti-diabetic drug Metformin. Good biocompatibility results were found with MTT and hemolysis assay. Owing to its simplicity and effectiveness, the as-prepared C-dots offered great promise for blood sugar diagnosis and treatment.

Precursor Concentration Effect on Optical Properties of Carbon Dots from Cassava’s Peels

<p class="Abstract">Carbon dots (C-dots) are a new type of fluorescent nanoparticles that can be readily synthesized from natural sources, such as cassava’s peels. In this work, C-dots were synthesized from cassava’s peels using low temperature green synthesis based. The Green synthesis techniques were done by using water as a solvent non-chemical and natural sources. The Synthesis was done using various concentrations of precursor from 0.25%, 0.50%, 1.0% and 2.0%. Optical properties of C-dots were characterized using spectrophotometer UV-Vis, photoluminescence (PL) and time resolved photoluminescence (TRPL). The concentration of precursor lead to differences in molecular density and content of preparation thus affecting optical properties. The performance of C-dots optical properties were dominated by the transition of electrons n–π* on structure aromtic C=O which originate from the surface of C-dots. The result of C-dots sample with a concentration of 2.0% precursors has the best emission effiency. This provides the potential for C-dots cassava’s peels in the aqueous solution to be applied as cellular bioimaging and biosensing metal ions and salts.</p>

Antimicrobial Carbon-Based Nanomaterials

Infectious diseases caused by bacterial pathogens have been a serious threat to public health for decades and remain one of the major concerns of our society. Control and prevention of pathogen contamination are effective ways to reduce the risk of infectious disease. The advancement of nanotechnology has brought various nanomaterials with remarkable properties for a wide range of applications, including the antimicrobial fields. Carbon-based nanomaterials represent a class of relatively safe and cost-effective materials yet with desirable antimicrobial properties which are applicable to the antimicrobial fields. This research explored the antimicrobial activity of two types of carbon-based nanomaterials and their composites: carbon nanotubes (CNTs) and carbon “quantum” dots. We investigated the applications of single-walled CNTs (SWNTs), multi-walled CNTs (MWNTs), CNTs-Ag, CNTs-chemicals/natural peptides, CNTs-NIR, CNTs-coated surfaces, for inactivation of bacterial pathogens, bacterial spores, and viruses, inhibition of biofilms, as well as for capturing and concentrating bacterial pathogens (Fig. 1). The results indicated that SWNTs effectively inactivated Salmonella, E. coli cells, Bacillus anthracis cells in suspensions, but did not effective in inactivating bacterial spores. The microbial activity of SWNTs was concentration-, treatment time-, buffer-, CNTs’ length- and surface group- dependent. SWNTs coupled with H2O2 or NaOCl had the synergistic effect contributed by the two individual antimicrobial mechanisms of SWNTs and the oxidizing antimicrobial chemicals, and resulted in much stronger sporicidal effect compared to treatment with H2O2 or NaOCl alone at the same concentrations, doubling the log reduction of viable spore number (~3.3 log vs. ~1.6 log). MWNTs were not effective in inactivating bacterial cells in suspension, but MWNTs modified surfaces, including MWNT forest on silicon wafer and MWNT sheet on poly(methyl methacrylate) (PMMA) film, significantly increased surface hydrophobicity and enhanced the attachment of spores on their surfaces compared to the uncoated substrates, respectively, showing their potential as adsorbents for removal of Bacillus spores from fluids. Carbon dots (CDots), defined as small carbon nanoparticles with various surface passivation schemes, with their optical properties and photocatalytic functions, were evaluated for their photoinduced bactericidal functions, with the results suggesting that the dots were highly effective in bacteria-killing with visible light illumination (Fig.1). Correlations between CDots property, including CDots quantum yield and surface functionalization, and antimicrobial activity were studied. Concentration- and time- dependency of CDots’ antimicrobial activity was examined. Mechanistic implications of the results will be discussed. Challenges and opportunities in the development of carbon dots into a new class of effective visible/natural light-responsible bactericidal agents for a variety of bacteria control applications will be discussed Acknowledgement: The research was supported by NSF grants: DMR# 1701399 and NIH grant R15GM114752. Figure 1