Vital Staining Research Articles

Safety Profile of Lutein- Versus Triamcinolone Acetonide-Based Vitreous Staining.

To assess the safety profile of a new lutein-based vitreous dye (LB-VD) formulation compared with various triamcinolone acetonide (TA) formulations with and without subsequent exposure to perfluorodecalin (PFD) in vitro. Human adult retinal pigment epithelial cells (ARPE-19) were treated with the following formulations: undiluted preserved TA (TA-BA), diluted preserved TA (D-TA-BA), preservative-free TA (TA-PF), and LB-VD. First, cell tolerability was evaluated with MTT, LDH, and ATPlite assays after 1, 5, and 30 minutes of exposure to each tested formulation. Then, cells were sequentially exposed to formulations and PFD. After 24 hours of exposure to PFD, cell tolerability was evaluated through MTT and ATPlite assays. Among the formulations tested, LB-VD showed the highest levels of cell viability, cell metabolism, and cell proliferation and induced the lowest release of LDH, whereas the TA-based formulations demonstrated a cytotoxic effect on ARPE-19 cells in vitro. After subsequent 24-hour exposure to PFD, a greater reduction of cell viability was noted for all the formulations; however, this reduction was not significant only for the combination LB-VD-PFD, which was the best tolerated condition. LB-VD showed a better safety profile compared with all TA-based formulations, even when used in combination with PFD. In surgical practice, LB-VD may be preferred to TA-based formulations for vitreous staining in the light of its more favorable safety profile.

Inactivation of Giardia intestinalis cysts in water using a sonochemical method based on mid-high-frequency waves

Giardia intestinalis is a pollutant of food and water, resistant to conventional disinfection treatments and its elimination requires effective methods action. Herein, mid-high-frequency ultrasound (375 kHz), which produces HO• and H2O2, was used as an alternative method of treatment to inactivate Giardia intestinalis cysts in water. The effect of ultrasound power (4.0, 11.2, 24.4 W) on the sonogeneration of radicals was tested, showing that 24.4 W was the condition most favorable to treat the parasite. The viability of the protozoan cysts was evaluated using the immunofluorescence technique and vital stains, showing this protocol was useful to quantify the parasite. The sonochemical method (at 375 kHz and 24.4 W) was applied at different treatment times (10, 20, and 40 min). A significant decrease in the protozoan concentration (reduction of 52.4% of viable cysts) was observed after 20 min of treatment. However, the extension of treatment time up to 40 min did not increase the inactivation. Disinfecting action was associated with attacks on the Giardia intestinalis cyst by sonogenerated HO• and H2O2 (which may induce structural damage, even the cell lysis). For future work is recommended to test combinations with UVC or Fenton process to enhance the inactivating action of this method.•Mid-high-frequency ultrasound produces HO• and H2O2 profitable to inactivate Giardia intestinalis.•Immunofluorescence technique and vital stains allowed us to quantify the parasite viability.•Giardia intestinalis cysts concentration decreased by 52.4% after only 20 min of sonication.

Use of light-emitting diode fluorescence microscopy to detect acid-fast bacilli in sputum as proficient alternative tool in the diagnosis of pulmonary tuberculosis in countries with limited resource settings.

Despite recent advances in the development of more sensitive technologies for the diagnosis of tuberculosis (TB), in resource-limited settings, the diagnosis continues to rely on sputum smear microscopy. This is because smear microscopy is simple, cost-efficient and the most accessible tool for the diagnosis of TB. Our study evaluated the performance of light-emitting diode fluorescence microscopy (LED-FM) using auramine/rhodamine (auramine) and the fluorescein di-acetate (FDA) vital stain in the diagnostic of pulmonary TB in Bamako, Mali. Sputum smear microscopy was conducted using the FDA and auramine/rhodamine staining procedures on fresh samples using LED-FM to evaluate the Mycobacterium TB (MTB) metabolic activity and to predict contagiousness. Mycobacterial culture assay was utilized as a gold standard method. Out of 1401 TB suspected patients, 1354 (96.65%) were retrieved from database, which were MTB complex culture positive, and 47 (3.40%) were culture negative (no mycobacterial growth observed). Out of the 1354 included patients, 1343 (95.86%), were acid-fast bacillus (AFB) positive after direct FDA staining, 1352 (96.50%) AFB positive after direct Auramine, and 1354 (96.65%) AFB positive with indirect auramine after digestion and centrifugation. Overall, the FDA staining method has a sensitivity of 98.82%, while the sensitivity of Auramine with direct observation was 99.48%, and 99.56% with the indirect examination. This study showed that, using fresh sputum both auramine/rhodamine and FDA are highly sensitive methods in diagnosing pulmonary TB and could be easily used in countries with limited resource settings.

Absence of Synergistic Effect of Toluidine Blue and Cytomorphometry in Discriminating Dysplasia in Oral Exfoliative Cytology

Numerous tools and techniques such as vital stain, autofluorescence, exfoliative cytology, histomorphometry, etc. were explored in the detection of dysplasia, but have variable sensitivity and specificity. The present study evaluated the effect of toluidine blue in increasing the accuracy of histomorphometry analysis in detection of the dysplasia in OPMDs on exfoliative cytology. An experimental, observational, cross-sectional research was performed on patients attending dental hospitals and in

Optimization of postoperative protocol and diagnosis of inflammatory complications of post-extraction wounds at the stages of prosthetic rehabilitation

Was to optimize the protocol for postoperative orthopedic management and diagnosis of wound healing zones in patients after multiple teeth extractions. At the Department of Orthopedic Dentistry and Orthodontics, Ryazan State Medical University, orthopedic treatment of 30 patients was carried out after the extraction of upper teeth. Patients were divided into 3 groups depending on the used immediate prostheses: (I) traditional, (II) having a shock-absorbing polypropylene mesh in their design, (III) having a drug reservoir made of elastic plastic and a ring made of monomer-free plastic in the region of the closing borders prosthesis. To assess the effectiveness of treatment, patients on days 5, 10, 20 underwent diagnostic supravital staining of the mucous membrane using an iodine-containing solution, planimetric control, and computerized capillaroscopy. In group I by the end of the observation period a pronounced dynamics of inflammation persisted in 30% of cases, the objective signs of which amounted to 12.5±2.06 mm2 of the area of the positive indicator of supravital staining, while in group II it was 7.2±2.09, in group III - 8.3±1.41 mm2 (p≤0.05). According to the results of supravital staining and capillaroscopy at day 20, in group II morphological and objective indicators of inflammation productivity were significantly higher than in group III: the density of the vascular network in group II was 52.5±2.17, in group III - 46.3±2.4 capillary loops/µm2, staining area 7.2±2.09 and 8.3±1.41 mm2, respectively (p≤0.05). More active wound healing in patients of group II was achieved by optimizing the design of the immediate prosthesis. An accessible and objective assessment of the severity of inflammation using vital staining allows you to accurately assess the dynamics of wound healing with a blurred or unexpressed clinical picture and timely suggest the features of inflammation to correct the course of treatment.

Coumarin-based acid dye for fluorescent staining of calcium carbonate particles

Vital fluorescence staining of calcium-containing structures in calcifying organisms is a powerful tool for the study of biocalcification. The main dyes used in this field have green or red fluorescence, which may be overlapped with the fluorescence of chlorophyll and other organic substances. We synthesized a novel coumarin-based fluorescent dye QA2 that stains calcium carbonate and calcium phosphate. The fluorescence of this dye depends from environment, it is enhanced in non-polar medium with a shift of the emission maximum to the blue spectrum region. Small vaterite and calcium phosphate particles adsorb QA2 on the surface and exhibit predominantly green fluorescence, while low surface area calcite crystals are stained in bulk and show additional intense blue fluorescence. The ability of the QA2 dye to generate blue fluorescence of calcium carbonate may be useful for tracking calcium carbonate formation at living organisms in the presence of green and red fluorescent organic substances.

Efficacy of tissue autofluorescence and tissue vital staining in evaluation of potentially malignant oral disorders - A comparative pilot study

Efficacy of tissue autofluorescence and tissue vital staining in evaluation of potentially malignant oral disorders - A comparative pilot study

Germination and viability of wild sunflower species seeds stored at room temperature and low humidity for 38 years

The effects of prolonged storage on the germination and viability of seeds of sunflower crop wild relatives stored under less-than-optimal conditions in working genebanks is not known. Seeds of two wild annual species, Helianthus annuus (common wild sunflower) and annual H. petiolaris (prairie sunflower), were stored at room temperature (20 to 22°C) and low humidity of ∼ 22% in the laboratory for 38 years. Germination of stored annual sunflower seeds was 5.5%, while that of prairie sunflower seeds was 0.75%, compared with the germination of freshly harvested seeds of 34.7 and 18.5%, respectively. Tetrazolium, a vital stain, indicated that the seeds were alive. The viability equations were used to predict final viability of the stored seeds. Using the three tests of viability (germination with and without gibberellic acid, and tetrazolium staining), all appeared to underestimate the actual condition of the stored seeds of annual sunflower, but provided better predictions for prairie sunflower. This study indicated that wild sunflower seeds can be stored at less than ideal conditions in working genebanks where viability decreases over time reducing germination, but gibberellic acid treatment can sustainably increase germination to produce a number of plants to maintain the genetic integrity of the original stored seeds often used in long-term prebreeding programmes.

Discomfort During Instillation Of Antihypertensives And Ocular Surface Condition In Glaucoma Patients

Background — An increase in the frequency of manifestations of dry eye syndrome (DES), against the background of hypotensive therapy, leads to a decrease in treatment adherence. After reformulation in the composition of a preservative-free preparation of a carbonic anhydrase inhibitor (CAI) (sodium benzoate was added), patient complaints of burning sensation during instillation became more frequent, which was the reason for our study. Objective — To evaluate the effect of sodium benzoate on the course of DES during local hypotensive therapy of glaucoma. Methods and Results — Group 1 consisted of 21 eyes with glaucoma receiving hypotensive therapy, Group 2 (20 eyes) included patients with suspected glaucoma not receiving therapy. Patients underwent standard diagnostic methods and examination of the ocular surface condition: tear break-up time test sensu Norn, Schirmer test, vital staining with lissamine green, and a survey based on the Ocular Surface Disease Index (OSDI) questionnaire. When a preservative-free CAI in combination therapy was replaced with the CAI containing sodium benzoate, no statistically significant change in IOP occurred after four weeks of treatment (p> 0.05). In both groups, the indicators characterizing the ocular surface condition did not change statistically significantly over the observation period. Conclusion — Replacement of preservative-free CAI in combination therapy of glaucoma with CAI with sodium benzoate does not lead to statistically significant changes in intraocular pressure. The ocular surface condition does not change statistically significantly over a month of observation. Instillation discomfort is not related to the pH of the preparation.

The biological effect of a combination of platelet lysate and amniotic membrane in buccal epithelium culture

Purpose: To study the biological effect of a combination of platelet lysate and amniotic membrane, preserved by various techniques, on human buccal epithelium culture. Materials and methods. Human amnion transplants were preserved using 3 methods: silicate drying, lyophilization, cryopreservation. The blood of healthy volunteers was used as a source of platelets. Platelet-rich plasma (PRP) with a platelet content over 1000 thousand/mcl and more was isolated from the donors blood, frozen at -80 °С and defrosted at 0–4 °С to prepare platelet lysate. Growth-stimulating effect of the amnion transplants was studied in different groups: control group 1 — without amnion and without PRP lysate; control group 2 — PRP lysate without amnion; experimental group 1 — amnion without PRP lysate; experimental group 2 — amnion samples combined with PRP lysate. The study was carried out on the example of human buccal epithelium culture of 3–5 passages. The dynamics of cell growth was evaluated after 1, 2 and 3 days from the moment of seeding. The number of cells and their viability were evaluated using original methods based on vital cell staining and their examination in a fluorescent microscope. Results. All samples of preserved amnions were non-toxic and did not damage the structural and functional characteristics of the buccal epithelium. On the other hand, the use of amnion without PRP lysate did not have a growth-stimulating effect on cells. Among the amnion samples combined with PRP lysate, the combination of lyophilized amnion and PRP lysate was the most effective during the entire study period. Conclusions. Silicate drying, lyophilization and cryopreservation of the amniotic membrane makes it possible to obtain biocompatible and non-toxic transplants, based on human amnion. Lyophilized amnions are the most optimal for saturating PRP lysate. The combination of lyophilized amnion and PRP lysate stimulates cell growth in vitro without violating their structural integrity.

Divergent tooth development mechanisms of Mexican tetra fish (Astyanax mexicanus) of Pachón cave origin

The Mexican tetra (Astyanax mexicanus) is one of the fresh water teleost fish models in evolutionary developmental biology. The existence of two morphs: eyed, pigmented surface fish and blind depigmented cavefish from multiple cave populations, provides a unique system to study adaptive radiation. Compared to the adult surface fish, cavefish have large oral jaws with an increased number of structurally-complex teeth. Early tooth development has not been studied in detail in cavefish populations. In this study, bone-stained growth series and vital dye staining was used to trace the development and replacement of dentitions in Pachón cavefish. Our results show that first tooth eruption was delayed in cavefish compared to the surface fish. In particular, the first tooth eruption cycle persisted until 35 days post fertilization (dpf). Unlike surface fish, there are multicuspid teeth in cavefish first generation dentition. In addition to the teeth in the marginal oral jaw bones, Pachón cavefish have teeth in the ectopterygoid bone of the palatine roof. Next, we characterised the expression of ectodysplasin signalling pathway genes in tooth-forming regions of surface and cavefish. Interestingly, higher expression of Eda and Edar was found in cavefish compared to the surface fish. The altered ectodysplasin expression needs further investigation to confirm the different molecular mechanisms for tooth development in the oral and pharyngeal regions of surface fish and cavefish.

Cultivation and Imaging of S. latissima Embryo Monolayered Cell Sheets Inside Microfluidic Devices.

The culturing and investigation of individual marine specimens in lab environments is crucial to further our understanding of this highly complex ecosystem. However, the obtained results and their relevance are often limited by a lack of suitable experimental setups enabling controlled specimen growth in a natural environment while allowing for precise monitoring and in-depth observations. In this work, we explore the viability of a microfluidic device for the investigation of the growth of the alga Saccharina latissima to enable high-resolution imaging by confining the samples, which usually grow in 3D, to a single 2D plane. We evaluate the specimen's health based on various factors such as its growth rate, cell shape, and major developmental steps with regard to the device's operating parameters and flow conditions before demonstrating its compatibility with state-of-the-art microscopy imaging technologies such as the skeletonisation of the specimen through calcofluor white-based vital staining of its cell contours as well as the immunolocalisation of the specimen's cell wall. Furthermore, by making use of the on-chip characterisation capabilities, we investigate the influence of altered environmental illuminations on the embryonic development using blue and red light. Finally, live tracking of fluorescent microspheres deposited on the surface of the embryo permits the quantitative characterisation of growth at various locations of the organism.

Characteristics of pulsed electric field cardiac ablation porcine treatment zones with a focal catheter.

Pulsed electric field (PEF) therapies employ punctuated energy delivery to kill cells in a volume of tissue through mechanisms that are not dependent on thermal processes. A key component to successful cardiac ablation procedures is ensuring the generation of transmural, contiguous ablation zones, which requires in-depth knowledge regarding treatment sizes for a given therapeutic application. In this study, a series of acute treatments were delivered to porcine ventricles, where triphenyl tetrazolium chloride (TTC) vitality stain was used to identify treatment effect sizes for the three focal monopolar CENTAURI PEF cardiac ablation energy settings. Treatment depths were 5.7, 7.2, and 8.2 mm for the 19, 22, and 25 A energy settings, respectively. Gross pathology indicated umbral zones of hemorrhage surrounded by pale avital TTC-negative-negative tissue, which contrasted significantly from radiofrequency ablation (RF) controls. Histologically, treatment zones are identified by regions of contraction band necrosis and cardiomyocytolysis, which contrasted with RF control lesions composed primarily of coagulation necrosis. Together, these data indicate the ability for focal monopolar PEF treatments to generate deep treatment zones in cardiac ablation without incurring the gross or histological coagulative characteristics of RF thermal lesions.

Bivalve Oocyte Inviability Revealed Using a Simple Staining Technique

Photo 1. Cerastoderma edule (Linnaeus, 1758). (A) Emerged animals at low tide, (B) submerged animals with foot (F) and inhalant (IS) and exhalent (ES) siphons deployed. Animals in (A) and (B) are in their 3rd year (two annual growth rings are visible, corresponding to periostracal thickening) and thus both sexually mature. (C) Oocytes (OC) double-stained with Neutral Red vital stain and Trypan Blue mortal stain. Left, normal oocyte, right, dead oocyte. TB, undissolved Trypan Blue stain. (D) Oocytes stained with Neutral Red only; normal oocytes (NO) stain red, while dead oocytes do not stain. The TB stain proved effective, but cumbersome and costly to use in routine studies, while the more convenient and cost-efficient Neutral Red stain alone provided the same information. Photo credit: D. Chérel. These photographs illustrate the article “Evolutionary and ecological insights from vital staining of bivalve oocytes: A Red Queen at the sweepstakes?” by Peter G. Beninger, Daphné Chérel, Gaël Le Pennec, and Sandra E. Shumway published in Ecosphere. https://doi.org/10.1002/ecs2.4047

Tunable Polymeric Mixed Micellar Nanoassemblies of Lutrol F127/Gelucire 44/14 for Oral Delivery of Praziquantel: A Promising Nanovector against Hymenolepis nana in Experimentally-Infected Rats.

Hymenolepiasis represents a parasitic infection of common prevalence in pediatrics with intimidating impacts, particularly amongst immunocompromised patients. The present work aimed to snowball the curative outcomes of the current mainstay of hymenolepiasis chemotherapy, praziquantel (PRZ), through assembly of polymeric mixed micelles (PMMs). Such innovative nano-cargo could consolidate PRZ hydrosolubility, extend its circulation time and eventually upraise its bioavailability, thus accomplishing a nanoparadigm for hymenolepiasis tackling at lower dose levels. For consummating this goal, PRZ-PMMs were tailored via thin-film hydration technique integrating a binary system of Lutrol F127 and Gelucire 44/14. Box-Behnken design was planned for optimizing the nanoformulation variables employing Design-Expert® software. Also, in Hymenolepis nana-infected rats, the pharmacodynamics of the optimal micellar formulation versus the analogous crude PRZ suspension were scrutinized on the 1st and 3rd days after administration of a single oral dose (12.5 or 25 mg/kg). Moreover, in vitro ovicidal activity of the monitored formulations was estimated utilizing Fuchsin vital stain. Furthermore, the in vivo pharmacokinetics were assessed in rats. The optimum PRZ-PMMs disclosed conciliation between thermodynamic and kinetic stability, high entrapment efficiency (86.29%), spherical nanosized morphology (15.18 nm), and controlled-release characteristics over 24 h (78.22%). 1H NMR studies verified PRZ assimilation within the micellar core. Additionally, the in vivo results highlighted a significant boosted efficacy of PRZ-PMMs manifested by fecal eggs output and worm burden reduction, which was clearly evident at the lesser PRZ dose, besides a reversed effect for the intestinal histological disruptions. At 50 µg/mL, PRZ-PMMs increased the percent of non-viable eggs to 100% versus 47% for crude PRZ, whilst shell destruction and loss of embryo were only clear with the applied nano-cargo. Moreover, superior bioavailability by 3.43-fold with elongated residence time was measured for PRZ-PMMs compared to PRZ suspension. Practically, our results unravel the potential of PRZ-PMMs as an oral promising tolerable lower dose nanoplatform for more competent PRZ mass chemotherapy.

Stains and dyes in Ophthalmology

Stains and dyes are very effective diagnostic and therapeutic tools in ophthalmology. Although non-invasive, diagnostic dyes are objectively used to directly visualize, identify and track microscopic ocular structures for anterior, as also posterior segment disorders. These are very useful, both for anterior and posterior segment disorders. Diagnosis and management of retinal vascular disorders have been revolutionised, ever since the introduction of fluorescein. It is used in an array of disorders of the anterior segment also. The term staining is used to describe epithelial disruption and other pathophysiological changes which can be seen when we use the dyes topically. The dyes used topically are called vital stains.

Endocytoscopic Observation of Esophageal Lesions: Our Own Experience and a Review of the Literature.

This review outlines the process of the development of the endocytoscope (EC) with reference to previously reported studies including our own. The EC is an ultra-high-magnification endoscope capable of imaging at the cellular level. The esophagus is the most suitable site for EC observation because it is amenable to vital staining. The diagnosis of esophageal lesions using EC is based on nuclear density and nuclear abnormality, allowing biopsy histology to be omitted. The observation of nuclear abnormality requires a magnification of ×600 or higher using digital technology. Several staining methods have been proposed, but single staining with toluidine blue or methylene blue is most suitable because the contrast at the border of a cancerous area can be easily identified. A three-tier classification of esophageal lesions visualized by EC is proposed: Type 1 (non-cancerous), Type 2 (endocytoscopic borderline), and Type 3 (cancerous). Since characteristic EC images reflecting pathology can be obtained from non-cancerous esophageal lesions, a modified form of classification with four additional characteristic non-cancerous EC features has also been proposed. Recently, deep-learning AI for analysis of esophageal EC images has revealed that its diagnostic accuracy is comparable to that of expert pathologists.

Options to optimize the orthopedic treatment protocol to prevent inflammatory complications at the immediate prosthetic stage in patients after multiple teeth extraction

BACKGROUND: Simultaneous multiple loss of teeth significantly increases the need for immediate orthopedic treatment in dental patients, often with the use of removable immediate dentures due to general somatic pathologies and local Dental Prostheses System features.
 AIM: The study aimed to optimize the orthopedic treatment protocol for patients after multiple teeth extractions.
 MATERIAL AND METHODS: As part of the study, the orthopedic preparation of 18 patients was conducted for further permanent prosthetics. Patients underwent tooth extraction in the upper or lower jaw amounting to the formation of included, combined, or terminal dentition defects. The following were used for patient treatment: a standard protocol for immediate prosthetics, a modified protocol, including an improved method of vital mucous membrane staining of the prosthetic bed in the surgical intervention area using standard and immediate original design prostheses. The treatment option effectiveness was evaluated based on the results of diagnostic monitoring of wound healing zones in the prosthetic bed area of immediate prostheses, including visual-palpation assessment, vital oral mucosa staining with an iodine-containing diagnostic solution to control inflammation, and a modified Doppler observation method.
 RESULTS: Study results revealed that all patients, who used standard immediate prostheses without considering the diagnostic control of inflammation areas, had objective signs of inflammation up to the 20th day of treatment with low microcirculation dynamics in the wound healing area. In 4 out of 6 patients using standard immediate prostheses, considering inflammation control, the vital staining indicators by day 20 indicated a possible trend toward chronic inflammation development in the prosthetic bed area, which was confirmed by an unstable microcirculation picture. The severity of inflammatory changes was insignificant in patients who received the original design of the immediate prosthesis, starting from the 7th day of observation and minimal by the 20th day. At this time the hemodynamics are physiologically normal.
 CONCLUSIONS: Based on the study results, the orthopedic rehabilitation protocols effectiveness, with the use of a modified design based on the immediate prosthesis and permanent diagnostic, mucous membrane staining of the prosthetic bed was established to detect inflammatory complications in the wound healing areas.

In vitro effect of bioscaffolds on viability and insulin‑producing function of human islets of Langerhans

The culture of islets of Langerhans with bioscaffolds – extracellular matrix (ECM) mimetics – can provide a native microenvironment suitable for islets. This is one of the main conditions for creating a pancreatic tissue equivalent.Objective: to compare the secretory capacity of viable human pancreatic islets in monoculture (control group) and cultured in the presence of two bioscaffolds: biopolymer collagen-based hydrogel scaffold (experimental group 1) and tissue-specific scaffold from decellularized deceased donor pancreas (experimental group 2).Materials and methods. Islets of Langerhans were isolated from the caudal pancreas using a collagenase technique. The viability of cultured islets was accessed by vital fluorescence staining, while secretory capacity was evaluated by enzyme-linked immunosorbent assay (ELISA).Results. Pancreatic islets cultured with bioscaffolds showed no signs of degradation and fragmentation, they remained viable throughout the entire period of observation (7 days). The monoculture of islets showed significant destructive changes during this period. Basal insulin levels in experimental groups 1 and 2 increased by 18.8% and 39.5% on day 1 of culture compared to the control group, by 72.8% and 102.7% on day 4 of incubation, and by 146.4% and 174.6% on day 7, respectively. The insulin secretion level of islets with tissue-specific scaffolds was 17.4% higher than that when cultured with biopolymer collagen-based scaffolds.Conclusion. Biopolymer and tissue-specific ECM mimetics contribute not only to preservation of the viability of isolated islets of Langerhans but also maintain their insulin secretion capacity for 7 days at a higher level in comparison with monoculture. The experiments revealed that the use of a tissue-specific scaffold for the creation of a pancreatic tissue equivalent has slight potential advantage over biopolymer scaffold.

Evaluating disinfection performance of ultraviolet light-emitting diodes against the microalga Tetraselmis sp.: Assay methods, inactivation efficiencies, and action spectrum

Ultraviolet light-emitting diodes (UV-LEDs) are among the most compact devices and safest technologies in water disinfection systems. However, the validation of different assay methods to evaluate the disinfection performance of different wavelengths (265, 280, 285, and 300 nm) of UV-LEDs toward marine microalgae remains poorly characterized. In this study, several detection assays, namely the culture-based most probable number (MPN) assay, membrane integrity-based vital stain (VS) assay, chlorophyll fluorescence assay, and photochemical efficiency assay, were compared to assess the viability of the marine microalga Tetraselmis sp., with results indicating the MPN assay to be the most sensitive. In addition, this study compared the inactivation kinetics, inactivation efficiency, and energy efficiency of Tetraselmis sp. under different UV wavelengths, as assessed by the VS and MPN assays. The fluence-response curves of Tetraselmis sp. varied with assay and wavelength, with Geeraerd's model fitting all fluence-response microalgal inactivation curves. The results showed a non-significant difference in inactivation efficiency among different wavelengths of UV-LEDs (except for 300 nm) when using the VS assay. On the contrary, significant differences among all wavelengths were observed with respect to inactivation efficiency when using the MPN assay. The wavelength of 265 nm exhibited maximum inactivation efficiency, whereas 285 nm achieved optimal energy efficiency. The UV action spectrum of Tetraselmis sp. exhibited the peak at 265 nm, a finding which matched well with the absorbance spectrum of DNA. The observations from this study provide a theoretical basis and technical support for the application of the emerging UV-LED light sources in the algicidal treatment of marine water.