Photoactivated Carbon Dots for Inactivation of Foodborne Pathogens Listeria and Salmonella.

Foodborne pathogens have long been recognized as major challenges for the food industry and repeatedly implicated in food product recalls and outbreaks of foodborne diseases. This study demonstrated the application of a recently discovered class of visible-light-activated carbon-based nanoparticles, namely, carbon dots (CDots), for photodynamic inactivation of foodborne pathogens. The results demonstrated that CDots were highly effective in the photoinactivation of Listeria monocytogenes in suspensions and on stainless steel surfaces. However, it was much less effective for Salmonella cells, but treatments with higher CDot concentrations and longer times were still able to inactivate Salmonella cells. The mechanistic implications of the observed different antibacterial effects on the two types of cells were assessed, and the associated generation of intracellular reactive oxygen species (ROS), the resulting lipid peroxidation, and the leakage of nucleic acid and proteins from the treated cells were analyzed, with the results collectively suggesting CDots as a class of promising photodynamic inactivation agents for foodborne pathogens. IMPORTANCE Foodborne infectious diseases have long been recognized as major challenges in public health. Contaminations of food processing facilities and equipment with foodborne pathogens occur often. There is a critical need for new tools/approaches to control the pathogens and prevent such contaminations in food processing facilities and other settings. This study reports a newly established antimicrobial nanomaterials platform, CDots coupled with visible/natural light, for effective and efficient inactivation of representative foodborne bacterial pathogens. The study will contribute to promoting the practical application of CDots as a new class of promising nanomaterial-based photodynamic inactivation agents for foodborne pathogens.

Enantiospecific Detection of D-Amino Acid through Synergistic Upconversion Energy Transfer.

D-amino acids (DAAs) are indispensable in regulating diverse metabolic pathways. Selective and sensitive detection of DAAs is crucial for understanding the complexity of metabolic processes and managing associated diseases. However, current DAA detection strategies mainly rely on bulky instrumentation or electrochemical probes, limiting their cellular and animal applications. Here we report an enzyme-coupled nanoprobe that can detect enantiospecific DAAs through synergistic energy transfer. This nanoprobe offers near-infrared upconversion capability, a wide dynamic detection range, and a detection limit of 2.2 µM, providing a versatile platform for in vivo noninvasive detection of DAAs with high enantioselectivity. These results potentially allow real-time monitoring of biomolecular handedness in living animals, as well as developing antipsychotic treatment strategies.

NaCeF4:Gd,Tb Scintillator as an X-ray Responsive Photosensitizer for Multimodal Imaging-Guided Synchronous Radio/Radiodynamic Therapy.

Photosensitizers (PSs) that are directly responsive to X-ray for radiodynamic therapy (RDT) with desirable imaging abilities have great potential applications in cancer therapy. Herein, the cerium (Ce)-doped NaCeF4:Gd,Tb scintillating nanoparticle (ScNP or scintillator) is first reported. Due to the sensitization effect of the Ce ions, Tb ions can emit fluorescence under X-ray irradiation to trigger X-ray excited fluorescence (XEF). Moreover, Ce and Tb ions can absorb the energy of secondary electrons generated by X-ray to produce reactive oxide species (ROS) for RDT. With the intrinsic absorption of X-ray by lanthanide elements, the NaCeF4:Gd,Tb ScNPs also act as a computed tomography (CT) imaging contrast agent and radiosensitizers for radiotherapy (RT) sensitization synchronously. Most importantly, the transverse relaxation time of Gd3+ ions is shortened due to the doping of Ce and Tb ions, leading to the excellent performance of our ScNPs in T2-weighted MR imaging for the first time. Both in vitro and in vivo studies verify that our synthesized ScNPs have good performance in XEF, CT, and T2-weighted MR imaging, and a synchronous RT/RDT is achieved with significant suppression on tumor progression under X-ray irradiation. Importantly, no systemic toxicity is observed after intravenous injection of ScNPs. Our work highlights that ScNPs have potential in multimodal imaging-guided RT/RDT of deep tumors.

Systematic Toxicity Evaluations of High-Performance Carbon "Quantum" Dots.

Carbon dots (CDots) in a general structure of small carbon nanoparticles with various surface passivation schemes have emerged to represent a new class of carbon nanomaterials in now a rapidly advancing and expanding research field. Among various synthesis methods, the use of pre-processed and selected small carbon nanoparticles for deliberate chemical functionalization of the particle surface with organic molecules have produced high-performance and structurally better defined CDots. Specifically, small organic molecules 2,2'-(ethylenedioxy)bis(ethylamine) and 3-ethoxypropylamine were used for the effective surface passivation of the carbon nanoparticles via chemical functionalization to yield CDots that are brightly fluorescent and also structurally ultra-compact, amenable to various desired cell imaging applications. Thus, a systematic evaluation of these CDots on their cytotoxicity profiles is necessary, and performed in this study by using a diverse selection of cell lines. Also for fluorescence imaging, CDots were modified with their encapsulating selected organic dyes for much enhanced red/near-IR fluorescence emissions. These modified CDots with the dyes as guest were also evaluated for their cytotoxicity profiles. The results suggest that the CDots without and with the guest dyes are generally nontoxic to the selected cell lines, further supporting the notion that CDots can be used as high-performance yet nontoxic bioimaging agents.

Rationally Designed Monodisperse Gd2 O3 /Bi2 S3 Hybrid Nanodots for Efficient Cancer Theranostics.

Multifunctional nanotheranostic agents are of particular importance in the field of precise nanomedicine. However, a critical challenge remains in the rational fabrication of monodisperse multicomponent nanoparticles with enhanced multifunctional characteristics for efficient cancer theranostics. Here, a rational and facile synthesis of monodisperse Gd2 O3 /Bi2 S3 hybrid nanodots (Gd/Bi-NDs) is demonstrated as a multifunctional nanotheranostic agent using a albumin nanoreactor for computed tomography (CT)/photoacoustics (PA)/magnetic resonance (MR) imaging and simultaneous photothermal tumor ablation. Two nanoprecipitation reactions in one albumin nanoreactor are simultaneously conducted to generate ultrasmall Gd/Bi-NDs with both orthorhombic Bi2 S3 and cubic Gd2 O3 nanostructures. Their hybrid nanostructure generates distinctly enhanced longitudinal relaxivity in the spatially confined albumin nanocage as compared to monocomponent Gd2 O3 nanodots. Moreover, such hybrid nanodots possess multiple desirable characteristics including superior photobleaching resistance, efficient cellular uptake, preferable tumor accumulation, good in vivo clearance, and negligible acute toxicity, thereby leading to complementary PA/CT/MR imaging with spatial and anatomic characteristics, as well as effective photothermal tumor ablation without regrowth. These results represent a promising approach to fabricate monodisperse multicomponent nanotheranostic agents for efficient cancer theranostics.

Continuous amperometric hydrogen gas sensing in ionic liquids.

We report an innovative amperometric hydrogen sensor that addresses current primary issues (i.e. signal drift, low selectivity and speed) in continuous and real-time gas sensing. Utilizing the unique properties and redox reactions of hydrogen in the ionic liquids (ILs), 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Bmpy][NTf2] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2], we demonstrate the real-time and continuous sensing of hydrogen with high sensitivity, selectivity and repeatability in both anaerobic and aerobic conditions using simple constant potential amperometry. The varying adsorption of hydrogen at the IL-electrode interface in different ILs is shown to allow tuning of the sensitivity of the sensor. Taking advantage of oxygen in ambient conditions, we demonstrate that the unique chemical reaction of the analyte with the oxygen enables selective quantification of hydrogen in an ambient environment. A sensor calibration based on a kinetics analysis (i.e. the change of the rate of current signal (ΔI/Δt1/2)) rather than an equilibrium analysis was demonstrated to allow fast and quantitative analysis of hydrogen concentration. The ionic liquid hydrogen sensor exhibits high sensitivity, selectivity, speed, accuracy, repeatability and stability. Together with the miniaturization and affordability of amperometric sensor readout electronics, the IL-based electrochemical gas sensor is expected to enable area-wide sensing instead of point measurements for environmental, health and occupational safety applications.

Ionic Strength, Surface Charge, and Packing Density Effects on the Properties of Peptide Self-Assembled Monolayers.

The various environmental parameters of packing density, ionic strength, and solution charge were examined for their effects on the properties of the immobilized peptide mimotope CH19 (CGSGSGSQLGPYELWELSH) that binds with the therapeutic antibody Trastuzumab (Herceptin) on a gold substrate. The immobilization of CH19 onto gold was examined with a quartz crystal microbalance (QCM). The QCM data showed the presence of intermolecular interactions resulting in the increase of viscoelastic properties of the peptide self-assembled monolayer (SAM). The CH19 SAM was diluted with CS7 (CGSGSGS) to decrease the packing density as CH19/CS7. The packing density and ionic strength parameters were evaluated by atomic force microscopy (AFM), ellipsometry, and QCM. AFM and ellipsometry showed a distinct conformational difference between CH19 and CH19/CS7, indicating a relationship between packing density and conformational state of the immobilized peptide. The CH19 SAM thickness was 40 Å with a rough topology, while the CH19/CS7 SAM thickness was 20 Å with a smooth topology. The affinity studies showed that the affinity of CH19 and CH19/CS7 to Trastuzumab were both on the order of 107 M-1 in undiluted PBS buffer, while the dilution of the buffer by 1000× increased both SAMs affinities to Trastuzumab to the order of 1015 M-2 and changed the binding behavior from noncooperative to cooperative binding. This indicated that ionic strength had a more pronounced effect on binding properties of the CH19 SAM than packing density. Electrochemical impedance spectroscopy (EIS) was conducted on the CH19/CS7 SAM, which showed an increase in impedance after each EIS measurement cycle. Cyclic voltammetry on the CH19/CS7 SAM decreased impedance to near initial values. The impact of the packing density, buffer ionic strength, and local charge perturbation of the peptide SAM properties was interpreted based on the titratable sites in CH19 that could participate in the proton transfer and water equilibrium.

Modified Facile Synthesis for Quantitatively Fluorescent Carbon Dots.

A simple yet consequential modification was made to the popular carbonization processing of citric acid - polyethylenimine precursor mixtures to produce carbon dots (CDots). The modification was primarily on pushing the carbonization processing a little harder at a higher temperature, such as the hydrothermal processing condition of around 330 °C for 6 hours. The CDots thus produced are comparable in spectroscopic and other properties to those obtained in other more controlled syntheses including the deliberate chemical functionalization of preprocessed and selected small carbon nanoparticles, demonstrating the consistency in CDots and reaffirming their general definition as carbon nanoparticles with surface passivation by organic or other species. Equally significant is the finding that the modified processing of citric acid - polyethylenimine precursor mixtures could yield CDots of record-setting fluorescence performance, approaching the upper limit of being quantitatively fluorescent. Thus, the reported work serves as a demonstration on not only the need in selecting the right processing conditions and its associated opportunities in one-pot syntheses of CDots, but also the feasibility in pursuing the preparation of quantitatively fluorescent CDots, which represents an important milestone in the development and understanding of these fluorescent carbon nanomaterials.

Metallic Nanostructures for Multispectral Filters.

A metal-dielectric-metal structure with cross-shaped-hole array in metal thin films is studied for plasmonic multispectral filters, which covers visible to near-infrared wavelengths. Surface plasmons are induced from incident wave by a periodic array of nanostructures, then the localized surface plasmon polaritons oscillate in the cavity, which is formed by the two layers of metals through near-field excitation. The transmission spectrum of the metal-dielectric-metal structure with cross-shaped-hole array is investigated with the finite-difference time-domain method; our simulations show that the features of the hole, and the refractive index and the thickness of the dielectric layer all affect the optical spectral performance. This metal-dielectric-metal structure provides additional flexibility in tuning transmission spectrum due to its Fabry-Perot cavity property. Our study shows that it is possible to obtain desired multispectral filters by programming the refractive index and thickness of the dielectric layer, and these parameters of the metallic structures.

How the substituents in corannulene and sumanene derivatives alter their molecular assemblings and charge transport properties?--A theoretical study with a dimer model.

The substituent effects on the structures, intermolecular interactions and charge transport properties of a series of corannulene and sumanene derivatives were investigated by DFT method. The intermolecular interaction energy and the potential energy surface of the dimers were also calculated and analyzed in detail, which showed several local energy minima and demonstrated the possible dimer structures in experiment. In addition, the reorganization energy, transfer integral, and carrier mobility were explored to measure the charge transport properties of these substituted corannulenes and sumanenes at different configurations for investigating the substituent effects. Our study is closely related to the experiment and previous theoretical investigation and provides a better understanding of the structure-property relationships for these substituted corannulenes and sumanenes.

Electrode Reactions Coupled with Chemical Reactions of Oxygen, Water and Acetaldehyde in an Ionic Liquid: New Approaches for Sensing Volatile Organic Compounds.

Water and oxygen are ubiquitous present in ambient conditions. This work studies the unique oxygen, trace water and a volatile organic compound (VOC) acetaldehyde redox chemistry in a hydrophobic and aprotic ionic liquid (IL), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([Bmpy] [NTf2]) by cyclic voltammetry and potential step methods. One electron oxygen reduction leads to superoxide radical formation in the IL. Trace water in the IL acts as a protic species that reacts with the superoxide radical. Acetaldehyde is a stronger protic species than water for reacting with the superoxide radical. The presence of trace water in the IL was also demonstrated to facilitate the electro-oxidation of acetaldehyde, with similar mechanism to that in the aqueous solutions. A multiple-step coupling reaction mechanism between water, superoxide radical and acetaldehyde has been described. The unique characteristics of redox chemistry of acetaldehyde in [Bmpy][NTf2] in the presence of oxygen and trace water can be controlled by electrochemical potentials. By controlling the electrode potential windows, several methods including cyclic voltammetry, potential step methods (single-potential, double-potential and triple-potential step methods) were established for the quantification of acetaldehyde. Instead of treating water and oxygen as frustrating interferents to ILs, we found that oxygen and trace water chemistry in [Bmpy][NTf2] can be utilized to develop innovative electrochemical methods for electroanalysis of acetaldehyde.

Nanocomposite-Based Photodynamic Therapy Strategies for Deep Tumor Treatment.

Photodynamic therapy (PDT), as an emerging clinically approved modality, has been used for treatment of various cancer diseases. Conventional PDT strategies are mainly focused on superficial lesions because the wavelength of illumination light of most clinically approved photosensitizers (PSs) is located in the UV/VIS range that possesses limited tissue penetration ability, leading to ineffective therapeutic response for deep-seated tumors. The combination of PDT and nanotechnology is becoming a promising approach to fight against deep tumors. Here, the rapid development of new PDT modalities based on various smartly designed nanocomposites integrating with conventionally used PSs for deep tumor treatments is introduced. Until now many types of multifunctional nanoparticles have been studied, and according to the source of excitation energy they can be classified into three major groups: near infrared (NIR) light excited nanomaterials, X-ray excited scintillating/afterglow nanoparticles, and internal light emission excited nanocarriers. The in vitro and in vivo applications of these newly developed PDT modalities are further summarized here, which highlights their potential use as promising nano-agents for deep tumor therapy.

Harness arsenic in medicine: current status of arsenicals and recent advances in drug delivery.

INTRODUCTION: Arsenicals have a special place in the history of human health, acting both as poison and medicine. Having been used to treat a variety of diseases in the past, the success of arsenic trioxide (ATO) in treating acute promyelocytic leukemia (APL) in the last century marked its use as a drug in modern medicine. To expand their role against cancer, there have been clinical uses of arsenicals worldwide and progress in the development of drug delivery for various malignancies, especially solid tumors. AREAS COVERED: In this review, conducted on Google Scholar [1977-2024], we start with various forms of arsenicals, highlighting the well-known ATO. The mechanism of action of arsenicals in cancer therapy is then overviewed. A summary of the research progress in developing new delivery approaches (e.g. polymers, inorganic frameworks, and biomacromolecules) in recent years is provided, addressing the challenges and opportunities in treating various malignant tumors. EXPERT OPINION: Reducing toxicity and enhancing therapeutic efficacy are guidelines for designing and developing new arsenicals and drug delivery systems. They have shown potential in the fight against cancer and emerging pathogens. New technologies and strategies can help us harness the potency of arsenicals and make better products.

Freezing process influences cake appearance of a lyophilized amorphous protein formulation with low solid content and high fill configuration.

Low solid content and high fill drug product configuration pose special challenges for achieving elegant cake appearance after lyophilization. In this study, such a configuration for a protein formulation required lyophilization within a narrow primary drying operating space to obtain elegant cakes. Freezing process optimization was explored as a solution. A Design of Experiment (DoE) approach was used to evaluate the effect of shelf cooling rate, annealing temperature, and their interaction on cake appearance. The slope of product resistance (Rp) vs. dried layer thickness (Ldry) was used as the quantitative response because elegant cake appearance correlated with a lower initial Rp and positive slope. As the Rp vs. Ldry slope can be experimentally established within the first 1/6th of the total primary drying duration, partial lyophilization runs were executed, allowing for rapid screening. The DoE model revealed that a slow cooling rate (≤0.3 °C/min) and high annealing temperature (≥-10 °C) resulted in a better cake appearance. Furthermore, X-ray micro-computed tomography showed that elegant cakes exhibited uniform porous structure and larger pores, while inelegant cakes showed dense top layers with smaller pores. With the optimized freezing process, the primary drying operating space was broadened with improved cake appearance and batch homogeneity.

Synergistic Phototherapy-Molecular Targeted Therapy Combined with Tumor Exosome Nanoparticles for Oral Squamous Cell Carcinoma Treatment.

Oral squamous cell carcinoma (OSCC) contributes to more than 90% of all oral malignancies, yet the performance of traditional treatments is impeded by limited therapeutic effects and substantial side effects. In this work, we report a combinational treatment strategy based on tumor exosome-based nanoparticles co-formulating a photosensitizer (Indocyanine green) and a tyrosine kinase inhibitor (Gefitinib) (IG@EXOs) for boosting antitumor efficiency against OSCC through synergistic phototherapy-molecular targeted therapy. The IG@EXOs generate distinct photothermal/photodynamic effects through enhanced photothermal conversion efficiency and ROS generation, respectively. In vivo, the IG@EXOs efficiently accumulate in the tumor and penetrate deeply to the center of the tumor due to passive and homologous targeting. The phototherapy effects of IG@EXOs not only directly induce potent cancer cell damage but also promote the release and cytoplasmic translocation of Gefitinib for achieving significant inhibition of cell proliferation and tumor angiogenesis, eventually resulting in efficient tumor ablation and lymphatic metastasis inhibition through the synergistic phototherapy-molecular targeted therapy. We envision that the encouraging performances of IG@EXOs against cancer pave a new avenue for their future application in clinical OSCC treatment.

A pH-Activatable Copper-Biomineralized Proenzyme for Synergistic Chemodynamic/Chemo-Immunotherapy against Aggressive Cancers.

Artificial enzymes have demonstrated therapeutic benefits against diverse malignant tumors, yet their antitumor potencies are still severely compromised by non-selective catalysis, low atomic-utilization efficiency, and undesired off-target toxicity. Herein, it is reported that peroxidase-like biomineralized copper (II) carbonate hydroxide nanocrystals inside single albumin nanocages (CuCH-NCs) act as a pH-activatable proenzyme to achieve tumor-selective and synergistic chemodynamic/chemo-immunotherapy against aggressive triple-negative breast cancers (TNBCs). These CuCH-NCs show pH-sensitive Cu2+ release, which spontaneously undergoes glutathione (GSH)-mediated reduction into Cu+ species for catalyzing the evolution of H2 O2 into hydroxyl radicals (·OH) in a single-atom-like manner to cause chemodynamic cell injury, and simultaneously activates non-toxic disulfiram to cytotoxic complex for yielding selective chemotherapeutic damage via blocking cell proliferation and amplifying cell apoptosis. CuCH-NCs exhibit considerable tumor-targeting capacity with deep penetration depth, thus affording preferable efficacy against orthotopic breast tumors through synergistic chemodynamic/chemotherapy, together with good in vivo safety. Moreover, CuCH-NCs arouse distinct immunogenic cell death effect and upregulate PD-L1 expression upon disulfiram combination, and thus synergize with anti-PD-L1 antibody to activate adaptive and innate immunities, together with relieving immunosuppression, finally yielding potent antitumor efficacy against both primary and metastatic TNBCs. These results provide insights into smart and high-performance proenzymes for synergistic therapy against aggressive cancers.

Holographically Activatable Nanoprobe via Glutathione/Albumin-Mediated Exponential Signal Amplification for High-Contrast Tumor Imaging.

Glutathione (GSH)-activatable probes hold great promise for in vivo cancer imaging, but are restricted by their dependence on non-selective intracellular GSH enrichment and uncontrollable background noise. Here, a holographically activatable nanoprobe caging manganese tetraoxide is shown for tumor-selective contrast enhancement in magnetic resonance imaging (MRI) through cooperative GSH/albumin-mediated cascade signal amplification in tumors and rapid elimination in normal tissues. Once targeting tumors, the endocytosed nanoprobe effectively senses the lysosomal microenvironment to undergo instantaneous decomposition into Mn2+ with threshold GSH concentration of ≈ 0.12 mm for brightening MRI signals, thus achieving high contrast tumor imaging and flexible monitoring of GSH-relevant cisplatin resistance during chemotherapy. Upon efficient up-regulation of extracellular GSH in tumor via exogenous injection, the relaxivity-silent interstitial nanoprobe remarkably evolves into Mn2+ that are further captured/retained and re-activated into ultrahigh-relaxivity-capable complex by stromal albumin in the tumor, and simultaneously allows the renal clearance of off-targeted nanoprobe in the form of Mn2+ via lymphatic vessels for suppressing background noise to distinguish tiny liver metastasis. These findings demonstrate the concept of holographic tumor activation via both tumor GSH/albumin-mediated cascade signal amplification and simultaneous background suppression for precise tumor malignancy detection, surveillance, and surgical guidance.

Organic-Inorganic Hybrid Cuprous Halide Scintillators for Flexible X-ray Imaging.

Recently, organic-inorganic hybrid scintillators have received more and more attention because of their merits of easy preparation, good stability, and nontoxicity. Considering the high cost of traditional inorganic scintillators, here we describe experimental investigations of a low-cost zero-dimensional scintillator comprising organic-inorganic hybrid cuprous halide and its capabilities for sensitive X-ray detection and flexible X-ray imaging. This scintillator is synthesized using a facile antisolvent diffusion method with large scalability (50 g). The crystal structure shows an unreported plane rhombus cuprous halide core, which also demonstrates outstanding photoluminescence with a high quantum yield (99.5%), excellent radioluminescence with an efficient internal light yield (25 000 photon/MeV), and sensitive X-ray response with a low detection limit (40.4 nGy/s). The organic-inorganic hybrid chemical feature allows the fabrication of a flexible film based on this scintillator for fine-resolution X-ray radiography. These advantages endow our organic-inorganic hybrid scintillator with promising potential in wearable and portable medical devices.

Comparative electrochemical scanning tunneling microscopy study of nonionic fluorosurfactant zonyl FSN self-assembled monolayers on Au(111) and Au(100): a potential-induced structural transition.

We investigate the structure of nonionic fluorosurfactant zonyl FSN self-assembled monolayers on Au(111) and Au(100) in 0.05 M H(2)SO(4) as a function of the electrode potential by electrochemical scanning tunneling microscopy (ECSTM). On Au(111), a (3(1/2) × 3(1/2))R30° arrangement of the FSN SAMs is observed, which remains unchanged in the potential range where the redox reaction of FSN molecules does not occur. On Au(100), some parallel corrugations of the FSN SAMs are observed, which originate from the smaller distance and the repulsive interaction between FSN molecules to make the FSN molecules deviate from the bridging sites, and ECSTM reveals a potential-induced structural transition of the FSN SAMs. The experimental observations are rationalized by the effect of the intermolecular interaction. The smaller distance between molecules on Au(100) results in the repulsive force, which increases the probability of structural change induced by external factors (i.e., the electrode potential). The appropriate distance and interactions of FSN molecules account for the stable structure of FSN SAMs on Au(111). Surface crystallography may influence the intermolecular interaction through changing the molecular arrangements of the SAMs. The results benefit the molecular-scale understanding of the behavior of the FSN SAMs under electrochemical potential control.

Single-walled carbon nanotubes coupled with near-infrared laser for inactivation of bacterial cells.

In this study, single-walled carbon nanotubes (SWCNTs) coupled with near infrared (NIR) laser treatment to enhance SWCNT's antimicrobial activity were studied. Salmonella, agram-negative pathogenic bacteria, was used as a model bacteria in this study. We found that NIR treatment (800 nm, 475 mW, for 20 min) to bacterial suspension with 50 microg/ml SWCNTs reduced the cell growth by approximately 55.5% compared with the cell sample with 50 microg/ml SWCNTs alone. Determined by the plating method, the viable cell number in the SWCNTs-NIR treated samples reduced by 2.2 log, while SWCNTs alone only had 0.7 log reduction. Imaging analysis of bacterial cells with and without NIR treatment correlated well with the growth and viable cell reduction measurement. We also found that the enhancement of SWCNTs' antimicrobial activity by NIR treatment was related to the NIR power, the NIR treatment time, and SWCNTs' concentration. The localized heating of SWCNTs under NIR treatment was the likely mechanism to enhance the antimicrobial efficiency of SWCNTs beyond its intrinsic antimicrobial activity. The results of this study suggested that SWCNTs-NIR treatment has the potential to be an effective antimicrobial method.