Difluoroboron Complexes Based on Benzimidazole-Phenolates as Blue Emitters.

Novel four-coordinated boron complexes (1-5) were synthesized via a reaction between BF3·CH3OH and benzimidazole-phenolate ligands (L1-L5), which are N,O-donors. These complexes exhibit intense blue emission in the solution and solid states accompanied by notable fluorescence quantum yields (ΦF). The study of the structure-property relation, through theoretical and experimental approaches, revealed a distinctive trend where compounds incorporating electron-donating substituents (methyl and ethoxy groups) in the phenolate moiety manifest shifts in emission wavelengths across the blue spectrum, concomitant with an increase in ΦF. Furthermore, the incorporation of an aromatic ring into the benzimidazole moiety considerably intensifies the rate of radiative relaxation from excited states. Notably, in the solid phase, either as a crystalline powder or loaded into polymer films, these modified complexes maintain or even surpass ΦF values observed in molecular solutions, ranging from 0.18 to 0.57, depending on the substitution. This characteristic makes these compounds attractive for applications in optoelectronics. All of the compounds were characterized using 1H, 13C, 11B, and 19F NMR, elemental analysis, and the molecular structures were corroborated through single-crystal X-ray diffraction analysis. Computational calculations via time-dependent density functional theory further elucidate the tunability of optical bandgaps through group substitution on ligands, aligning well with experimental observations.

Entangled Two-Photon Absorption in Transmission-Based Experiments: Deleterious Effects from Linear Optical Losses.

Recently different experimental schemes have been proposed to study the elusive phenomenon of entangled two-photon absorption (ETPA) in nonlinear materials. The attempts to detect ETPA using transmission-based schemes have led to results whose validity is currently under debate because the ETPA signal can be corrupted or emulated by artifacts associated with linear optical losses. The present work addresses the issue of linear losses and the corresponding artifacts in transmission-based ETPA experiments through a new approach that exploits the properties of a Hong-Ou-Mandel (HOM) interferogram. Here, we analyze solutions of rhodamine B (RhB), commonly used as a model of a nonlinear medium in ETPA studies. Then, by using the HOM interferometer as a sensing device, we first demonstrate the equivalence of the standard transmission vs pump power ETPA experiments, presented in many reports, with our novel approach of transmission vs two-photon temporal delay. Second, a detailed study of the effects of optical losses, unrelated to ETPA, over the HOM interferogram is carried out by: (1) characterizing RhB in solutions prepared with different solvents and (2) considering scattering losses introduced by silica nanoparticles used as a controlled linear loss mechanism. Our results clearly expose the deleterious effects of linear optical losses over the ETPA signal when standard transmission experiments are employed and show how, by using the HOM interferogram as a sensing device, it is possible to detect the presence of such losses. Finally, once we showed that the HOM interferogram discriminates properly linear losses, our study also reveals that under the specific experimental conditions considered here, which are the same as those employed in many reported works, the ETPA was not unequivocally detected.

Spectral Considerations of Entangled Two-Photon Absorption Effects in Hong-Ou-Mandel Interference Experiments.

Recently, different experimental methods intended to detect the entangled two-photon absorption (ETPA) phenomenon in a variety of materials have been reported. The present work explores a different approach in which the ETPA process is studied based on the changes induced in the visibility of a Hong-Ou-Mandel (HOM) interferogram. By using an organic solution of Rhodamine B as a model of nonlinear material interacting with entangled photons at ∼800 nm region produced by spontaneous parametric down-conversion (SPDC) Type-II, the conditions that make possible to detect changes in the visibility of a HOM interferogram upon ETPA are investigated. We support the discussion of our results by presenting a model in which the sample is considered as a spectral filtering function which fulfills the energy conservation conditions required by ETPA, allowing us to explain the experimental observations with good agreement. We believe that this work represents a new perspective to studying the ETPA interaction, by using an ultrasensitive quantum interference technique and a detailed mathematical model of the process.

Bimetallic Ruthenium Nitrosyl Complexes with Enhanced Two-Photon Absorption Properties for Nitric Oxide Delivery.

One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+ , where FT is a fluorenyl-substituted terpyridine ligand, and bpy the 2,2'-bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF-CC-TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis-RuNO2 and bis-RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one-photon absorption (OPA) correlates well with the TD-DFT computations. A spectacular effect is observed at two-photon absorption (TPA) with a large enhancement of the molecular cross-section (σTPA ), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA-based drug delivery.

Early implant placement in ridge preserved extraction sockets: A pre-clinical in vivo study.

OBJECTIVES: The aim was to analyse the outcomes of early implant placement after 6 and 12 weeks of healing in ridge preserved sites in a canine model. MATERIALS AND METHODS: Implants were placed in second maxillary incisors sites in 9 dogs 6 weeks after grafting of the sockets with 90% deproteinized bovine bone mineral in 10% collagen matrix (DBBMC) and closure with resorbable type I/III porcine collagen matrix (PCM). The implants were randomly assigned to 6 (T6) and 12 (T12) weeks of healing. RESULTS: The percentage of bone-to-implant contact (%BIC), old bone, new bone and residual DBBMC was similar between T6 and T12. In relation to the implant shoulder (IS), the original bone crest (IS-ROB) was more apical on the buccal than the palatal side. The regenerated bone crest (IS-C) and IS-ROB were similar between groups. However, the distance from IS to first bone-to implant contact (IS-fBIC) was significantly less in T12 compared with T6 (p = .022; Wilcoxon signed-rank test). The bucco-palatal ridge dimensions between T6 and T12 were similar. CONCLUSIONS: This study confirms that implants can successfully be placed early in ridge preserved maxillary second incisor sites and are osseointegrated by 6 weeks. There were significantly lower IS-fBIC values at 12 weeks than at 6 weeks on the buccal aspect. The original buccal bone crest underwent greater corono-apical resorption than the palatal crest. The %BIC, relative proportions of mineralized tissues and dimensions of the alveolar ridge demonstrated stability between 6 and 12 weeks of healing.

Core carbo-mer of an Extended Tetrathiafulvalene: Redox-Controlled Reversible Conversion to a carbo-Benzenic Dication.

carbo-Benzene is an aromatic molecule devised by inserting C2 units within each C-C bond of the benzene molecule. By integrating the corresponding carbo-quinoid core as bridging unit in a π-extended tetrathiafulvalene (exTTF), it is shown that a carbo-benzene ring can be reversibly formed by electrochemical reduction or oxidation. The so-called carbo-exTTF molecule was thus experimentally prepared and studied by UV-visible absorption spectroscopy and cyclic voltammetry, as well as by X-ray crystallography and by scanning tunneling microscopy (STM) on a surface of highly oriented pyrolytic graphite (HOPG). The molecule and its oxidized and reduced forms were subjected to a computational study at the density functional theory (DFT) level, supporting carbo-aromaticity as a driving force for the formation of the dication, radical cation, and radical anion. By allowing co-planarity of the dithiolylidene rings and carbo-quinoidal core, carbo-exTTFs present a promising new class of redox-active systems.

Modal interferometer based on a single mechanically induced long-period fiber grating and a nanoparticles-coated film section.

A modal interferometer by a single mechanically induced long-period fiber grating (MI-LPFG) using a half-length coating fiber is presented. The coating material used for this Letter is a film of silica nanoparticles doped with an organic chromophore. The silica nanoparticles, with diameters within the range of 40-50 nm, were deposited over 3.5 cm length of fiber by the dip-coating method, forming a film with a thickness between 500 and 1250 nm. Then the modal interferometer was implemented by inscribing the MI-LPFG over the coated fiber section and a similar fiber length of the uncoated fiber. The experimental results show high-contrast transmission bands, where the position and depth of the absorption envelope band are finely selected by the grating period, the pressure applied, and the film thickness. The novel modal interferometer architecture based on a single MI-LPFG, combined with a functionalized nanoparticles coating film, offers an attractive platform for the development of fiber sensors and other fiber-based devices.

Silole-Based Red Fluorescent Organic Dots for Bright Two-Photon Fluorescence In vitro Cell and In vivo Blood Vessel Imaging.

Robust luminescent dyes with efficient two-photon fluorescence are highly desirable for biological imaging applications, but those suitable for organic dots fabrication are still rare because of aggregation-caused quenching. In this work, a red fluorescent silole, 2,5-bis[5-(dimesitylboranyl)thiophen-2-yl]-1-methyl-1,3,4-triphenylsilole ((MesB)2 DTTPS), is synthesized and characterized. (MesB)2 DTTPS exhibits enhanced fluorescence efficiency in nanoaggregates, indicative of aggregation-enhanced emission (AEE). The organic dots fabricated by encapsulating (MesB)2 DTTPS within lipid-PEG show red fluorescence peaking at 598 nm and a high fluorescence quantum yield of 32%. Upon excitation at 820 nm, the dots show a large two-photon absorption cross section of 3.43 × 10(5) GM, which yields a two-photon action cross section of 1.09 × 10(5) GM. These (MesB)2 DTTPS dots show good biocompatibility and are successfully applied to one-photon and two-photon fluorescence imaging of MCF-7 cells and two-photon in vivo visualization of the blood vascular of mouse muscle in a high-contrast and noninvasive manner. Moreover, the 3D blood vasculature located at the mouse ear skin with a depth of over 100 µm can also be visualized clearly, providing the spatiotemporal information about the whole blood vascular network.

Effectiveness of Enteral Versus Oral Nutrition With a Medium-Chain Triglyceride Formula to Prevent Malnutrition and Growth Impairment in Infants With Biliary Atresia.

OBJECTIVES: The aim of this study was to compare the effectiveness of oral (PO) versus enteral nutrition (EN) medium-chain triglyceride (MCT) containing-formula to prevent malnutrition and growth impairment in infants with biliary atresia (BA) waiting for a liver transplant. METHODS: A total of 15 infants, 3 to 9 months old with BA were included. They were randomly assigned to either PO or EN. For 12 weeks, both groups received an MCT formula fortified with glucose polymers and corn oil to reach a caloric density between 0.8 and 1 kcal/mL. The formula given to the PO group was administered ad libitum and that given via EN was infused through a nasogastric tube to reach 140% of the energy intake recommended by the Dietary Recommended Intake guidelines. Protein intake was adjusted to 4 to 5 g/kg present weight. Outcome variables were growth and nutritional status evaluated periodically by anthropometric indicators. Biochemical and hematological variables were evaluated through the study. RESULTS: Baseline clinical, nutritional, biochemical, and hematological variables showed no differences between the study groups. Baseline length/age was <-2 SD in 10 of the 15 patients; in the PO group, it fell <-3 SD, whereas in the EN group, it remained stable. Head circumference z score dropped 0.6 SD in the PO group, whereas in the EN group it remained stable. Triceps skinfold values improved in the infants taking EN, P < 0.001. The frequency of adverse effects--respiratory infection and diarrhea--was higher in the EN group. No biochemical or hematological differences were observed between the study groups throughout the study. CONCLUSIONS: A 12-week EN trial with an MCT-fortified formula prevented malnutrition and growth impairment in infants with BA waiting for a liver transplant.

Strong Dipolar Effects on an Octupolar Luminiscent Chromophore: Implications on their Linear and Nonlinear Optical Properties.

Design parameters derived from structure-property relationships play a very important role in the development of efficient molecular-based functional materials with optical properties. Here, we report on the linear and nonlinear optical properties of a fluorene-derived dipolar system (DS) and its octupolar analogue (OS), in which donor and acceptor groups are connected by a phenylacetylene linkage, as a strategy to increase the number of delocalized electrons in the π-conjugated system. The optical nonlinear response was analyzed in detail by experimental and theoretical methods, showing that, in the octupolar system OS, the dipolar effects induced a strong two-photon absorption process whose magnitude is as large as 2210 GM at infrared wavelengths. Solvatochromism studies were implemented to obtain further insight on the charge transfer process. We found that the triple bond plays a fundamental role in the linear and nonlinear optical responses. The strong solvatochromism behavior in DS and OS was analyzed by using four empirical solvent scales, namely Lippert-Mataga, Kamlet-Taft, Catalán, and the recently proposed scale of Laurence et al., finding consistent results of strong solvent polarizability and viscosity dependence. Finally, the role of the acceptor groups was further studied by synthesizing the analogous compound 2DS, having no acceptor group.

Epidemiology and risk factors for infections due to AmpC ß-lactamase-producing Escherichia coli.

OBJECTIVES: To describe the prevalence and risk factors for infection due to AmpC ß-lactamase-producing Escherichia coli (AmpC-EC). METHODS: For the prevalence study, all clinical isolates of E. coli with reduced susceptibility to third-generation cephalosporins were prospectively included from June 2010 to November 2011. For risk factor analysis, a case-control study was conducted. Cases were patients with an infection due to AmpC-EC. Controls were patients infected with cephalosporin-susceptible E. coli, matched 1 : 2. Detection of blaAmpC genes was done with a multiplex AmpC-PCR, and hyperproduction of E. coli chromosomal blaAmpC by quantitative RT-PCR. Alteration of the blaAmpC promoter was studied by PCR and sequencing. RESULTS: We identified 243 (1.1%) AmpC-EC strains out of 21 563 clinical isolates. Three cases with strains carrying ESBLs, 18 strains that were considered due to colonization and 8 cases lost to clinical follow-up were excluded. Finally, 214 cases were included in the analysis. Ninety-one cases (42.5%) and 269 (62.8%) controls were strictly community acquired (P < 0.001). Thirty-five (16.3%) cases and 186 controls (43.5%) did not have any identifiable risk factor (P < 0.001). Among cases, 158 (73.8%) were found to harbour an acquired AmpC (73.4% CMY-2). Previous use of fluoroquinolones [OR 2.6 (95% CI 1.12-3.36); P = 0.008] was independently associated with AmpC-EC in the multivariate analysis. CONCLUSIONS: Prevalence of AmpC in E. coli remains low in our area. Plasmid acquisition (CMY type) represents the main mechanism of AmpC production. A high proportion of community-acquired isolates and patients with no identifiable risk factors were found. Previous use of fluoroquinolones was identified as a risk factor.

Difluorenyl carbo-Benzenes: Synthesis, Electronic Structure, and Two-Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores.

The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (C-C bonds for 3 a, C-C=C-C expanders for 3 b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections σ2PA. Z-scan measurements (under NIR femtosecond excitation) indeed showed that the C≡C expansion results in an approximately twofold increase in the σ2PA value, from 336 to 656 GM (1 GM = 10(-50) cm(4) s molecule(-1) photon(-1)) at λ = 800 nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of σ2PA(λi), in which λi = 2 hc/Ei, h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated σ2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z-scan results.

Morphine produces immunosuppressive effects in nonhuman primates at the proteomic and cellular levels.

Morphine has long been known to have immunosuppressive properties in vivo, but the molecular and immunologic changes induced by it are incompletely understood. To explore how these changes interact with lentiviral infections in vivo, animals from two nonhuman primate species (African green monkeys and pigtailed macaques) were provided morphine and studied using a systems biology approach. Biological specimens were obtained from multiple sources (e.g. lymph node, colon, cerebrospinal fluid, and peripheral blood) before and after the administration of morphine (titrated up to a maximum dose of 5 mg/kg over a period of 20 days). Cellular immune, plasma cytokine, and proteome changes were measured and morphine-induced changes in these parameters were assessed on an interorgan, interindividual, and interspecies basis. In both species, morphine was associated with decreased levels of Ki-67(+) T-cell activation but with only minimal changes in overall T-cell counts, neutrophil counts, and NK cell counts. Although changes in T-cell maturation were observed, these varied across the various tissue/fluid compartments studied. Proteomic analysis revealed a morphine-induced suppressive effect in lymph nodes, with decreased abundance of protein mediators involved in the functional categories of energy metabolism, signaling, and maintenance of cell structure. These findings have direct relevance for understanding the impact of heroin addiction and the opioids used to treat addiction as well as on the potential interplay between opioid abuse and the immunological response to an infective agent.

Levels of circulating myeloid subpopulations and of heme oxygenase-1 do not predict CD4(+) T cell recovery after the initiation of antiretroviral therapy for HIV disease.

The level (or frequency) of circulating monocyte subpopulations such as classical (CD14(hi)CD16(-)) and non-classical (CD14(dim)CD16(+)) monocytes varies during the course of HIV disease progression and antiretroviral therapy (ART). We hypothesized that such variation and/or differences in the degree to which these cells expressed the immunoregulatory enzyme, heme oxygenase-1 (HO-1), would be associated with CD4(+) T cell recovery after the initiation of ART. This hypothesis was tested in a cross-sectional study of four groups of HIV-infected subjects, including those who were seronegative, untreated virologic controllers [detectable viral load (VL) of <1000 copies/mL], untreated virologic non-controllers [VL > 10,000 copies/mL], and ART-mediated virologic controllers [VL < 75 copies/mL]. A longitudinal analysis of ART-treated subjects was also performed along with regression analysis to determine which biomarkers were associated with and/or predictive of CD4(+) T cell recovery. Suppressive ART was associated with increased levels of classical monocyte subpopulations (CD14(hi)CD16(-)) and decreased levels of non-classical monocyte populations (CD14(dim)CD16(+)). Among peripheral blood mononuclear cells (PBMCs), HO-1 was found to be most highly up-regulated in CD14(+) monocytes after ex vivo stimulation. Neither the levels of monocyte subpopulations nor of HO-1 expression in CD14(+) monocytes were significantly associated with the degree of CD4(+) T cell recovery. Monocyte subpopulations and HO-1 gene expression were, however, restored to normal levels by suppressive ART. These results suggest that the level of circulating monocyte subpopulations and their expression of HO-1 have no evident relationship to CD4(+) T cell recovery after the initiation of ART.

Ocular and nasal allergy symptom burden in America: the Allergies, Immunotherapy, and RhinoconjunctivitiS (AIRS) surveys.

Previous nationwide surveys of allergies in the United States have focused on nasal symptoms, but ocular symptoms are also relevant. This study determines the effects of ocular and nasal allergies on patients' lives. Telephone surveys of randomly selected U.S. households (the patient survey) and health care providers (provider survey) were conducted in the United States in 2012. Study participants were 2765 people ≥5 years of age who had ever been diagnosed with nasal or ocular allergies and 500 health care providers in seven specialties. Respondents to the patient survey reported a bimodal seasonal distribution of allergy symptoms, with peaks in March to May and September. Nasal congestion was the most common of the symptoms rated as "extremely bothersome" (39% of respondents), followed by red, itchy eyes (34%; p = 0.84 for difference in extreme bothersomeness of nasal and ocular symptoms). Twenty-nine percent of respondents reported that their or their child's daily life was impacted "a lot" when allergy symptoms were at their worst. Workers rated their mean productivity at 29% lower when allergy symptoms were at their worst (p < 0.001 compared with no symptoms). Providers reported that itchy eyes was the symptom causing most patients to seek medical treatment by pediatricians (73%), ophthalmologist/optometrists (72%), and nurse practitioners or physician assistants (62%), whereas nasal congestion was the symptom causing most patients to seek treatment from otolaryngologists (85%), allergist/immunologists (79%), and family medicine practitioners (64%). Ocular and nasal allergy symptoms substantially affected patients' lives and were comparable in their impact.

Advancing Primary Ciliary Dyskinesia Diagnosis through High-Speed Video Microscopy Analysis.

Primary ciliary dyskinesia (PCD) is an inherited disorder that impairs motile cilia, essential for respiratory health, with a reported prevalence of 1 in 16,309 within Hispanic populations. Despite 70% of Puerto Rican patients having the RSPH4A [c.921+3_921+6del (intronic)] founder mutation, the characterization of the ciliary dysfunction remains unidentified due to the unavailability of advanced diagnostic modalities like High-Speed Video Microscopy Analysis (HSVA). Our study implemented HSVA for the first time on the island as a tool to better diagnose and characterize the RSPH4A [c.921+3_921+6del (intronic)] founder mutation in Puerto Rican patients. By applying HSVA, we analyzed the ciliary beat frequency (CBF) and pattern (CBP) in native Puerto Rican patients with PCD. Our results showed decreased CBF and a rotational CBP linked to the RSPH4A founder mutation in Puerto Ricans, presenting a novel diagnostic marker that could be implemented as an axillary test into the PCD diagnosis algorithm in Puerto Rico. The integration of HSVA technology in Puerto Rico substantially enhances the PCD evaluation and diagnosis framework, facilitating prompt detection and early intervention for improved disease management. This initiative, demonstrating the potential of HSVA as an adjunctive test within the PCD diagnostic algorithm, could serve as a blueprint for analogous developments throughout Latin America.

Characterizing patients hospitalized without an acute care indication: A retrospective cohort study.

BACKGROUND: Hospitalizations by patients who do not meet acute inpatient criteria are common and overburden healthcare systems. Studies have characterized these alternate levels of care (ALC) but have not delineated prolonged (pALC) versus short ALC (sALC) stays. OBJECTIVE: To descriptively compare pALC and sALC hospitalizations-groups we hypothesize have unique needs. DESIGNS, SETTINGS, AND PARTICIPANTS: A retrospective study of hospitalizations from March-April 2018 at an academic safety-net hospital. MAIN OUTCOME AND MEASURES: Levels of care for pALC (>3 days) and sALC (1-3 days) were determined using InterQual©, an industry standard utilization review tool for determining the clinical appropriateness of hospitalization. We examined sociodemographic and clinical characteristics. RESULTS: Of 2365 hospitalizations, 215 (9.1%) were pALC, 277 (11.7%) were sALC, and 1873 (79.2%) had no ALC days. There were 17,683 hospital days included, and 28.3% (n = 5006) were considered ALC. Compared to patients with sALC, those with pALC were older and more likely to be publicly insured, experience homelessness, and have substance use or psychiatric comorbidities. Patients with pALC were more likely to be admitted for care meeting inpatient criteria (89.3% vs. 66.8%, p < .001), had significantly more ALC days (median 8 vs. 1 day, p < .001), and were less likely to be discharged to the community (p < .001). CONCLUSIONS: Patients with prolonged ALC stays were more likely to be admitted for acute care, had greater psychosocial complexity, significantly longer lengths of stay, and unique discharge needs. Given the complexity and needs for hospitalizations with pALC days, intensive interdisciplinary coordination and resource mobilization are necessary.

Trends in Nanoparticles for Leishmania Treatment: A Bibliometric and Network Analysis.

Leishmaniasis is a neglected tropical illness with a wide variety of clinical signs ranging from visceral to cutaneous symptoms, resulting in millions of new cases and thousands of fatalities reported annually. This article provides a bibliometric analysis of the main authors' contributions, institutions, and nations in terms of productivity, citations, and bibliographic linkages to the application of nanoparticles (NPs) for the treatment of leishmania. The study is based on a sample of 524 Scopus documents from 1991 to 2022. Utilising the Bibliometrix R-Tool version 4.0 and VOSviewer software, version 1.6.17 the analysis was developed. We identified crucial subjects associated with the application of NPs in the field of antileishmanial development (NPs and drug formulation for leishmaniasis treatment, animal models, and experiments). We selected research topics that were out of date and oversaturated. Simultaneously, we proposed developing subjects based on multiple analyses of the corpus of published scientific literature (title, abstract, and keywords). Finally, the technique used contributed to the development of a broader and more specific "big picture" of nanomedicine research in antileishmanial studies for future projects.

Two-photon absorption-based delivery of nitric oxide from ruthenium nitrosyl complexes.

Since the discovery of the numerous physiological roles exhibited by nitric oxide (NO), ruthenium nitrosyl (RuNO) complexes have been regarded as one of the most promising NO donors, stable, well tolerated by the body and capable of releasing NO locally and quantitatively, under light irradiation. This release can be achieved by two-photon absorption (TPA) processes, which allow the irradiation to be performed in the near infrared domain, where light has its maximum depth of penetration in biological tissues. This review provides a short introduction on the biological properties of NO, on RuNO complexes with photo-releasing capabilities, and on the origin of TPA properties in molecules. Then, the RuNO complexes with TPA capabilities are thoroughly discussed either as monometallic or polymetallic species.