Selectivity Filter Research Articles

PUFA stabilizes a conductive state of the selectivity filter in IKs channels.

In cardiomyocytes, the KCNQ1/KCNE1 channel complex mediates the slow delayed-rectifier current (IKs), pivotal during the repolarization phase of the ventricular action potential. Mutations in IKs cause long QT syndrome (LQTS), a syndrome with a prolonged QT interval on the ECG, which increases the risk of ventricular arrhythmia and sudden cardiac death. One potential therapeutical intervention for LQTS is based on targeting IKs channels to restore channel function and/or the physiological QT interval. Polyunsaturated fatty acids (PUFAs) are potent activators of KCNQ1 channels and activate IKs channels by binding to two different sites, one in the voltage sensor domain - which shifts the voltage dependence to more negative voltages - and the other in the pore domain - which increases the maximal conductance of the channels (Gmax). However, the mechanism by which PUFAs increase the Gmax of the IKs channels is still poorly understood. In addition, it is unclear why IKs channels have a very small single-channel conductance and a low open probability or whether PUFAs affect any of these properties of IKs channels. Our results suggest that the selectivity filter in KCNQ1 is normally unstable, contributing to the low open probability, and that the PUFA-induced increase in Gmax is caused by a stabilization of the selectivity filter in an open-conductive state.

PUFA stabilizes a conductive state of the selectivity filter in IKs channels

In cardiomyocytes, the KCNQ1/KCNE1 channel complex mediates the slow delayed-rectifier current (IKs), pivotal during the repolarization phase of the ventricular action potential. Mutations in IKs cause long QT syndrome (LQTS), a syndrome with a prolonged QT interval on the ECG, which increases the risk of ventricular arrhythmia and sudden cardiac death. One potential therapeutical intervention for LQTS is based on targeting IKs channels to restore channel function and/or the physiological QT interval. Polyunsaturated fatty acids (PUFAs) are potent activators of KCNQ1 channels and activate IKs channels by binding to two different sites, one in the voltage sensor domain – which shifts the voltage dependence to more negative voltages – and the other in the pore domain – which increases the maximal conductance of the channels (Gmax). However, the mechanism by which PUFAs increase the Gmax of the IKs channels is still poorly understood. In addition, it is unclear why IKs channels have a very small single-channel conductance and a low open probability or whether PUFAs affect any of these properties of IKs channels. Our results suggest that the selectivity filter in KCNQ1 is normally unstable, contributing to the low open probability, and that the PUFA-induced increase in Gmax is caused by a stabilization of the selectivity filter in an open-conductive state.

Cryo-EM structure of the heteromeric TRPC1/TRPC4 channel.

Transient receptor potential (TRP) ion channels have a crucial role as cellular sensors, mediating diverse physical and chemical stimuli. The formation of heteromeric structures expands the functionality of TRP channels; however, their molecular architecture remains largely unknown. Here we present the cryo-electron microscopy structures of the human TRPC1/TRPC4 heteromer in the apo and antagonist-bound states, both consisting of one TRPC1 subunit and three TRPC4 subunits. The heteromer structure reveals a distinct ion-conduction pathway, including an asymmetrically constricted selectivity filter and an asymmetric lower gate, primarily attributed to the incorporation of TRPC1. Through a structure-guided electrophysiological assay, we show that both the selectivity filter and the lower part of the S6 helix participate in deciding overall preference for permeating monovalent cations. Moreover, we reveal that the introduction of one lysine residue of TRPC1 into the tetrameric central cavity is enough to render one of the most important functional consequences of TRPC heteromerization: reduced calcium permeability. Our results establish a framework for addressing the structure-function relationship of the heteromeric TRP channels.

You are the main character: attribution and visibility on TikTok

ABSTRACT Hypertext theory from the 1990s and database theory from the 2000s still provide a useful foundation for explaining new authoring practices on the video-sharing platform TikTok, but this earlier literature may underestimate the importance of labour. Because hyperlinking is automated on the platform whenever composers select filters, hashtags, audio clips, and author references to other videos for “stitching” and “dueting” to remix from pre-existing databases of material, TikTok is characterised by rich attributional practices of citation. At the same time, the site’s users are keenly aware that search and recommendation algorithms may not showcase their published materials and that additional labour may be required for their contributions to be visible in the larger hyperlinked matrix of database participation. Users may also choose to de-link their content or the content of others. Case studies are drawn from variations of the 2020 “main character” meme, a 2023 moral panic about a supposedly dangerous TikTok “boat jumping” “trend”, and Ukrainian “war influencers”.

Noise filter using a periodic system of dual Helmholtz resonators

This study investigates noise reduction using a periodic arrangement of dual Helmholtz resonators and explores the introduction of defects within this periodic structure. The transfer matrix method was employed to carry out theoretical research. The computations of the interface response function approach results are verified, and consistent outcomes are demonstrated. The simulation results highlight the distinctive dual resonance frequencies of dual Helmholtz resonators. By differentiating dual Helmholtz resonators from traditional Helmholtz resonators, prospective applications for low-frequency noise reduction are envisioned. In this contribution, introducing defects in the middle of perfect dual Helmholtz resonators adds more value to the acoustic filter. In particular, the first neck and cavity of the defective dual Helmholtz resonator. This study shows that introducing a 2D-defect into identical dual Helmholtz resonators can improve the transmission of defect modes by taking advantage of the advantageous interaction of the resonant modes. In such arrangements, the entire structure functioned as a potent selective filter.

A Non-Invasive and DNA-free Approach to Upregulate Mammalian Voltage-Gated Calcium Channels and Neuronal Calcium Signaling via Terahertz Stimulation.

Mammalian voltage-gated calcium channels (CaV) play critical roles in cardiac excitability, synaptic transmission, and gene transcription. Dysfunctions in CaV are implicated in a variety of cardiac and neurodevelopmental disorders. Current pharmacological approaches to enhance CaV activity are limited by off-target effects, drug metabolism issues, cytotoxicity, and imprecise modulation. Additionally, genetically-encoded channel activators and optogenetic tools are restricted by gene delivery challenges and biosafety concerns. Here a novel terahertz (THz) wave-based method to upregulate CaV1.2, a key subtype of CaV, and boost CaV1-mediated Ca2+ signaling in neurons without introducing exogenous DNA is presented. Using molecular dynamics simulations, it is shown that 42.5 THz (7.05µm, 1418cm-1) waves enhance Ca2+ conductance in CaV1.2 by resonating with the stretching mode of the -COO- group in the selectivity filter. Electrophysiological recordings and Ca2+ imaging confirm that these waves rapidly, reversibly, and non-thermally increase calcium influx of CaV1.2 in HEK293 cells and induce acute Ca2+ signals in neurons. Furthermore, this irradiation upregulates critical CaV1 signals, including CREB phosphorylation and c-Fos expression, in vitro and in vivo, without raising significant biosafety risks. This DNA-free, non-invasive approach offers a promising approach for modulating CaV gating and Ca2+ signaling and treating diseases characterized by deficits in CaV functions.

Using syringe filtration after lab-scale adsorption processes potentially overestimates PFAS adsorption removal efficiency from non-conventional irrigation water.

The adsorption process, known for its cost-effectiveness and high efficiency, has been extensively investigated at the laboratory scale for removing per- and polyfluoroalkyl substances (PFAS) from non-conventional irrigation water. However, a syringe filtration step is commonly used when quantifying PFAS removal during this adsorption process, potentially leading to PFAS retention onto the filters and an overestimate of adsorption removal efficiency. Here, we assessed the retention of three prevalent PFAS (i.e., perfluorooctanoic acid [PFOA], perfluorooctane sulfonic acid [PFOS], and perfluorobutanoic acid [PFBA]) on six syringe filters. When filtering distilled deionized water spiked with 1µg/L and 100µg/L of each PFAS, we observed the highest and lowest PFAS recovery percentages by mixed cellulose ester (MCE) (0.20µm, 25mm; 97±11%, 101±4.8%) and polytetrafluoroethylene (0.45µm, 13mm; 61±37%, 80±28%), respectively. Under the initial concentration of 1µg/L and 100µg/L, PFOS had recovery percentages of 55±25% and 68±24%, significantly lower than 96±12% and 99±5% for PFOA and 95±8% and 97±4% for PFBA, highlighting the importance of PFAS functional groups. PFAS recovery percentage increased with filtration volume in the order of 80±28% (1mL)<85±21% (5mL)<90±18% (10mL). Using MCE to filter treated municipal wastewater spiked with 1µg/L and 100µg/L of each PFAS, we found recovery percentages>90% for all three PFAS. Our study underscores the significance of syringe filter selection and potential overestimate of PFAS removal efficacy by the lab-scale adsorption processes.

Constitutive sodium permeability in a C. elegans two-pore domain potassium channel

Two-pore domain potassium (K2P) channels play a central role in modulating cellular excitability and neuronal function. The unique structure of the selectivity filter in K2P and other potassium channels determines their ability to allow the selective passage of potassium ions across cell membranes. The nematode C. elegans has one of the largest K2P families, with 47 subunit-coding genes. This remarkable expansion has been accompanied by the evolution of atypical selectivity filter sequences that diverge from the canonical TxGYG motif. Whether and how this sequence variation may impact the function of K2P channels has not been investigated so far. Here, we show that the UNC-58 K2P channel is constitutively permeable to sodium ions and that a cysteine residue in its selectivity filter is responsible for this atypical behavior. Indeed, by performing in vivo electrophysiological recordings and Ca2+ imaging experiments, we demonstrate that UNC-58 has a depolarizing effect in muscles and sensory neurons. Consistently, unc-58 gain-of-function mutants are hypercontracted, unlike the relaxed phenotype observed in hyperactive mutants of many neuromuscular K2P channels. Finally, by combining molecular dynamics simulations with functional studies in Xenopus laevis oocytes, we show that the atypical cysteine residue plays a key role in the unconventional sodium permeability of UNC-58. As predicting the consequences of selectivity filter sequence variations in silico remains a major challenge, our study illustrates how functional experiments are essential to determine the contribution of such unusual potassium channels to the electrical profile of excitable cells.

Crown-Ether-Based Artificial K+ Selective Ionic Filter.

In this study, we have successfully synthesized bis (cholesterol-dibenzo-18-crown-6-ether)-pillar[5]arene compound 1 through a click reaction, which could spontaneously insert into lipid bilayers to form ion channel due to the membrane anchor cholesterol group and show significant transport activity of K+ superior to Na+, with a permeability ratio of K+/Na+ equal to 4.58. Compound 1 two crown ether modules act as selective filters similar to natural K+ channel, which are determined to 1:2 binding stoichiometry to K+ by Job's plot and NMR titration. This structurally unambiguously unimolecule artificial channel provides ideas for constructing highly K+/Na+ selective molecular filters.

A fitness distribution law for amino-acid replacements.

The effect of replacing the amino acid at a given site in a protein is difficult to predict. Yet, evolutionary comparisons have revealed highly regular patterns of interchangeability between pairs of amino acids, and such patterns have proved enormously useful in a range of applications in bioinformatics, evolutionary inference, and protein design. Here we reconcile these apparently contradictory observations using fitness data from over 350,000 experimental amino acid replacements. Almost one-quarter of the 20 × 19 = 380 types of replacements have broad distributions of fitness effects (DFEs) that closely resemble the background DFE for random changes, indicating an overwhelming influence of protein context in determining mutational effects. However, we also observe that the 380 pair-specific DFEs closely follow a maximum entropy distribution, specifically a truncated exponential distribution. The shape of this distribution is determined entirely by its mean, which is equivalent to the chance that a replacement of the given type is fitter than a random replacement. In this type of distribution, modest deviations in the mean correspond to much larger changes in the probability of falling in the far right tail, so that modest differences in mean exchangeability may result in much larger differences in the chance of a highly fit mutation. Indeed, we show that under the assumption that purifying selection filters out the vast majority of mutations, the maximum entropy distributions of fitness effects inferred from deep mutational scanning experiments predict the characteristic patterns of amino acid change observed in molecular evolution. These maximum entropy distributions of mutational effects not only provide a tuneable model for molecular evolution, but also have implications for mutational effect prediction and protein engineering.

Comparative exploration on EEG signal filtering using window control methods

Electroencephalography (EEG) is used to monitor brain activity. The brain signals consist of different frequency band signals delta, theta, alpha, beta, and gamma waves. The signals are affected by external noise which reduces the quality of the EEG signal due to which it becomes difficult to do further processing of EEG signals like feature extraction or extraction of meaningful features from EEG signal. Therefore, it becomes important to filter the noise from the EEG signal before feature extraction or classification of the EEG signal. The research article presents an overview of different types of windowing filter techniques like Rectangular, Bartlett, Hamming, Hanning, and Kaiser windows applied for finite impulse response (FIR) behavior which is used for EEG signal processing for different brain waves processed in different frequency bands. The comparative analysis is carried out in terms of the response time of brain frequency bands for different windowing filter techniques using the MATLAB 2023 signal processing simulation tool. The novelty of the work lies in estimating minimum latency and appropriate filter selection for various typical EEG waves, since the EEG signals are pre-supposed in the hardware chip design, noise elimination is the first step in high-performance computing applications. The Bartlett window band stop has an optimal response time of 12.666 s for delta waves, a highpass filter with a response time of 16.187 s for theta waves, a bandpass with a response time of 13.122 s for alpha waves, a highpass filter with a response time of 17.866 s for beta waves, and a highpass filter with a response time of 13.797 s for gamma waves. The Barlett window FIR filter is well-suited for EEG applications.

Bulk acoustic wave—Solidly mounted resonator with a-SiOCN:H as low-Z material

Bulk acoustic wave (BAW) filters have been proven to be of high demand in today's low power RF front-ends for mobile communication devices. Within the launch of 5G applications worldwide, especially in the region of new radio (nr-1) up to 6 GHz, defined frequency bands require filters of wide bandwidths, while simultaneously featuring steep edges and high out-of-band rejection. Due to the coexistence with 4G LTE (long term evolution) wireless standards as well as advanced data transfer concepts such as carrier aggregation, the increasing complexity of antenna systems forces the implementation of highly selective acoustic filters. In contrast to the widely used surface acoustic wave (SAW) technology, BAW filters appear with superior performance for frequencies above 1 GHz. This work describes the fabrication of a BAW-solidly mounted resonator (BAW-SMR) with a tailored material system of a-SiOCN:H as a low impedance (low-Z) material integrated within its acoustic Bragg mirror. A direct comparison to the widely used low-Z material of SiO2 with an acoustic impedance of around 13 MRayl is demonstrated by two equal resonator stacks by replacing only the uppermost low-Z thin film of the acoustic reflector. A single-mask design was chosen with platinum as a bottom electrode to ensure the most equal growth conditions for the piezoelectric aluminum nitride (AlN) layers on both reflectors’ surfaces featuring either the tailored a-SiOCN:H or standard SiO2. The a-SiOCN:H thin films were deposited by plasma-enhanced chemical vapor deposition and the according acoustic impedance was priorly depicted to 7.1 MRayl, which could be exploited to achieve an increase in the effective coupling coefficient beyond 7% as well as a resonator bandwidth of more than 60 MHz.

Novel gain-of-function mutants identify a critical region within CFTR membrane-spanning domain 2 controlling cAMP-dependent and ATP-independent channel activation

CFTR is an anion channel that has evolved from the mold of an ABC transporter. It possesses specific structural features, including a lateral portal between the cytoplasmic extensions of its transmembrane helices TM4 and TM6. This TM4-TM6 portal is lined by basic residues attracting anions from the cytosol towards the intracellular vestibule. Even though a symmetric, open portal is not observed at the level of the TM10/TM12 interface, basic amino acids are also present at this level, exposed to solvent in the vicinity of the regulatory R region, whose phosphorylation enables channel activation. Here, using all-atom molecular dynamics simulations in combination with functional and biochemical assays, we investigate the importance of these basic amino acids (R1158 and R1030), and of a neighboring aromatic amino acid (W846) in the regulation of CFTR activity. Results indicate that mutation of these amino acids globally increased channel activity and enabled channel opening by potentiators without the need to elevate cAMP levels. These effects (i) were observed even when the binding site of the potentiator VX-770 was mutated, revealing a probable independent mechanism, and (ii) were additive to one gain-of-function mutant within the selectivity filter. Taken together, our results indicate that the region of the membrane-spanning domain 2 (MSD2), symmetric to the lateral portal located between MSD1 TM4 and TM6, is a novel critical actor of CFTR regulation.

Optimizing gene selection for Alzheimer’s disease classification: A Bayesian approach to filter and embedded techniques

Alzheimer’s disease (AD) classification, which is crucial for identifying AD-associated genes, relies heavily on effective feature selection (FS) to tackle the curse of dimensionality. Traditional methods like filter, wrapper, and embedded techniques have their drawbacks, including ignoring feature independence, sensitivity to classifier choices, and high computational costs. Hybrid approaches combining these methods seek to harness their collective strengths but face challenges, particularly in selecting the optimal number of features from each method. This selection is typically manual or requires time-intensive k-fold cross-validation (KFCV), significantly increasing computational demands and complicating the process with the need for extensive parameter optimization across families, thereby escalating the complexity and resource requirements of model development. To overcome these challenges, this work proposes a framework for optimal FS and classification in AD using a combination of filter and embedded techniques, enhanced with hyperparameter tuning. Firstly, gene expression data (GED) from the AD Neuroimaging Initiative (ADNI) is preprocessed. Then, Chi-square filter selection is applied to decrease correlated features. Next, Logistic Regression with ElasticNet penalty (LREN) is employed to further refine the feature set. Finally, Bayesian Optimization (BO) is introduced to automatically determine the optimal number of features (k for Chi-square and max_features for LREN), iteratively evaluating different combinations to find the set that maximizes model accuracy. The selection process is used primarily in the function of BO to tune automatically the (k and max_features while minimizing the number of features and maximizing the accuracy of the Support Vector Machine (SVM). The SVM was used as a classifier to overcome the problem of embedded selection sensitivity to the model of selection. The tuned features are then used to select relevant features from the ADNI dataset and fitted to different models. We evaluated the performance of five classifiers—logistic regression (LR), SVM, Ridge Classifier (RC), stochastic gradient descent classifier (SGD), and Gaussian Naïve Bayes(GNB) across various metrics. Among these, SVM achieved 100% performance in all metrics. This approach significantly reduced the FS time and the number of initial features to 0.6% and 0.02%, respectively. Notably, it identified 6 out of 20 selected features as directly AD-related. Comparative analysis reveals that the proposed method outperforms existing approaches on the ADNI dataset and other datasets. Statistical tests were conducted to assess the significance of the results compared to other methods, confirming a significant improvement and underscoring the effectiveness of the proposed framework in optimal FS and biological relevance confirmation.

Introduction of oblique plane waves through a forcing source term in Euler equations

The propagation of shock waves generated by a transonic flow at the tip of a propeller blade is numerically calculated in order to determine the pressure footprint on an aircraft fuselage. An academic case is first proposed to validate the methodology. An incoming signal is built up as oblique harmonic plane waves. The signal is introduced in the computational domain using a Gaussian volume forcing term in the conservation of mass and energy equations. The Euler equations are solved in two dimensions using finite-difference schemes with low dispersion and dissipation. Selective filtering has also been integrated in the algorithm to remove grid-to-grid oscillations. The numerical solution is compared to an analytical solution based on the tailored Green function. An illustration for a realistic open rotor is then considered. The pressure signal near the blade tip, determined from a preliminary RANS simulation, is introduced using a volume source in a solver of the Euler equations.

Diatom frustule-inspired elastic metamaterials

Although a universally accepted definition of elastic metamaterials does not exist yet, the latter are often associated to man-made or artificially engineered media possessing properties typically not available in Nature. Pioneering studies have recently demonstrated that complex structural organizations, often arranged in a periodic and/or gradient manner and spanning multiple length scales, typically found in many biological systems, exhibit extraordinary absorption/reflection functionalities enhanced by local resonances or Bragg scattering mechanisms. This has opened the road to new designs of bio-inspired metamaterial. In this context, here we investigate the elastic dynamic response of diatom frustules, i.e., the exoskeleton structures of photosynthetic algae ubiquitously present throughout the planet in water environments. Firstly, we analyse and record their structural arrangement in nano- and micro- scales by using the Scanning Electro Microscopy (SEM) and the optical profilometer. The results of the analysis are transferred to the metamaterial design. Secondly, through numerical models, we show the possibility of certain frustule-inspired geometries to behave as frequency selective elastic filters thanks to the presence of elastic bandgaps. The work herein contributes to the perspective of elastic metamaterials inspired by Nature.

A conserved H-bond network in human aquaporin-1 is necessary for native folding and oligomerization

Aquaporins (AQPs) are α-helical transmembrane proteins that conduct water through membranes with high selectivity and permeability. For human AQP1, in addition to the functional Asn-Pro-Ala motifs and the aromatic/Arg selectivity filter within the pore, there are several highly conserved residues that form an expansive hydrogen-bonding network. Prior solid-state nuclear magnetic resonance studies and structural conservation analysis have detailed which residues may be involved in this network. We explored this network by mutating the sidechains or backbones involved in hydrogen-bonding, generating the following mutants: N127A, V133P, E142A, T187A, R195A, S196A. The fold and stability of these mutants were assessed with attenuated total reflection Fourier transform infra-red spectroscopy coupled with hydrogen/deuterium exchange upon increasing temperature. We found that replacement of any of the chosen residues to alanine leads to either partial instability or outright misfolding at room temperature, with the latter being most pronounced for the N127A, V133P, T187A, and R195A mutants. Deconvolution analysis of the amide I band revealed considerable secondary structure deviations, with some mutants exhibiting new random coil and β-sheet structures. We also found that some of these mutations potentially disrupt the oligomerization of human AQP1. BN-PAGE and DLS data provides evidence towards the loss of tetramers within most of the mutants, meanwhile only the S196A mutant retains tetrameric organization. The molecular dynamics simulation of the wild-type, and the N127A, E142A, and T187A mutants show that these mutations result in major rearrangements of intra- and inter-monomer hydrogen-bond networks. Overall, we show that specific point mutations that perturb hydrogen-bonding clusters result in severe misfolding in hAQP1 and disruption of its oligomerization. This data provides valuable insight into the structural stability of human aquaporin-1 and has implications towards other members of the AQP family, as these networks are largely conserved among a variety of human and non-mammalian AQP homologs.

Highly selective tri-wideband bandpass filter with adjustable passbands for high-performance space-based assets applications

A straightforward approach to designing a tri-wideband bandpass filter employing an E-shaped stepped impedance resonator loaded by an open-circuited tri-section stepped impedance stub (OSLTSIR) is explored in this paper. Upon analysis, it is ascertained that this resonator offers a distinct advantage by providing increased degrees of freedom for adjusting resonant frequencies, and the strength to generate transmission zeros at lower/upper stopbands. Capitalizing on these attributes, a tri-band bandpass filter is examined by combining this OSLTSIR with a half-wavelength resonator. The incorporation between the OSLTSIRs gives rise to creating a dual-wide band, while the introduced λ/2 resonators led to split the second passband into two, yielding in tri-band performance. The resultant filter operates at 8.25 GHz, 11.1 GHz, and 15.35 GHz with wide fractional bandwidths of 25.57 %, 18.45 %, and 24.6 %, respectively. Resonant frequencies and bandwidth can be controlled with substantial flexibility. The Experimental assessments confirm the existence of seven transmission zeros, showcasing high selectivity and good isolation. Besides, the fabricated structure maintains a compact size of (6.2 × 8.4) mm, about 0.12 λg2. The close agreement between the simulated and measured findings verifies its applicability for space-based asset applications.

Selective IR wavelengths multichannel filter based on the one-dimensional topological photonic crystals comprising hyperbolic metamaterial

In this research article, we have theoretically introduced a one-dimensional topological photonic crystal (1D TPC) design to provide a better stability due to imperfections and fluctuations in geometry compared to the traditional PC structures. The considered structure is designed by the combination of two different PCs, i.e., PC1 and PC2. PC1 consists of two layers of silicon (Si) and magnesium fluoride (MgF2), while PC2 contains a multilayer stack of MgF2 and hyperbolic metamaterial (HMM). Interestingly, the HMM layer is introduced as a composite of a dielectric material of indium arsenide (InAs), and nanocomposite of Ag nanoparticles inside a hosting medium of Y2O3. The foundations of our theoretical framework are based on Effective Medium Theory (EMT), the Transfer Matrix Method (TMM), and the Maxwell-Garnett model. Our research primarily focuses on utilizing our design as a pass/stop band filter for near-infrared (NIR) applications. Notably, this proposed design exhibits significant stability in the face of imperfections and variations. Our numerical findings highlight the influence of several geometric parameters including the refractive index of hosting medium for Ag nanoparticles, thicknesses, and filling fraction on the characteristics of the resulting filter. Remarkably, the results also reveal the emergence of multiple resonance peaks that maintain high stability against geometric tolerances. We believe our work presents a finite photonic crystal (PC) whose wave localization properties are resilient to random geometric imperfections, making it suitable for NIR filtering applications.

Prevention of Sunlight-Induced Cell Damage by Selective Blue-Violet-Light-Filtering Lenses in A2E-Loaded Retinal Pigment Epithelial Cells.

Blue light accelerates retinal aging. Previous studies have indicated that wavelengths between 400 and 455 nm are most harmful to aging retinal pigment epithelia (RPE). This study explored whether filtering these wavelengths can protect cells exposed to broad sunlight. Primary porcine RPE cells loaded with 20 µM A2E were exposed to emulated sunlight filtered through eye media at 1.8 mW/cm2 for 18 h. Filters selectively filtering out light over 400-455 nm and a dark-yellow filter were interposed. Cell damage was measured by apoptosis, hydrogen peroxide (H2O2) production, and mitochondrial membrane potential (MMP). Sunlight exposure increased apoptosis by 2.7-fold and H2O2 by 4.8-fold, and halved MMP compared to darkness. Eye Protect SystemTM (EPS) technology, filtering out 25% of wavelengths over 400-455 nm, reduced apoptosis by 44% and H2O2 by 29%. The Multilayer Optical Film (MOF), at 80% of light filtered, reduced apoptosis by 91% and H2O2 by 69%, and increased MMP by 73%, overpassing the dark-yellow filter. Photoprotection increased almost linearly with blue-violet light filtering (400-455 nm) but not with total blue filtering (400-500 nm). Selective filters filtering out 25% (EPS) to 80% (MOF) of blue-violet light offer substantial protection without affecting perception or non-visual functions, making them promising for preventing light-induced retinal damage with aesthetic acceptance for permanent wear.