Kinase PIM1 governs ferroptosis to reduce retinal microvascular endothelial cell dysfunction triggered by high glucose.

Previous studies have implicated targeting Pim-1 proto-oncogene, serine/threonine kinase (PIM1) as a preventive measure against high glucose-induced cellular stress and apoptosis. This study aimed to reveal the potential role and regulatory mechanism of PIM1 in diabetic retinopathy. Human retinal microvascular endothelial cells (hRMECs) underwent high glucose induction, and fluctuations in PIM1 levels were assessed. By overexpressing PIM1, its effects on the levels of inflammatory factors, oxidative stress indicators, migration and tube formation abilities, tight junction protein expression levels, and ferroptosis in hRMECs were identified. Afterwards, hRMECs were treated with the ferroptosis-inducing agent erastin, and the effect of erastin on the above PIM1 regulatory functions was focused on. PIM1 was downregulated upon high glucose, and its overexpression inhibited the inflammatory response, oxidative stress, cell migration, and tube formation potential in hRMECs, whereas elevated tight junction protein levels. Furthermore, PIM1 overexpression reduced intracellular iron ion levels, lipid peroxidation, and levels of proteins actively involved in ferroptosis. Erastin treatment reversed the impacts of PIM1 on hRMECs, suggesting the mediation of ferroptosis in PIM1 regulation. The current study has yielded critical insights into the role of PIM1 in ameliorating high glucose-induced hRMEC dysfunction through the inhibition of ferroptosis.

Auxetic piezoelectric effect in heterostructures.

Inherent symmetry breaking at the interface has been fundamental to a myriad of physical effects and functionalities, such as efficient spin-charge interconversion, exotic magnetic structures and an emergent bulk photovoltaic effect. It has recently been demonstrated that interface asymmetry can induce sizable piezoelectric effects in heterostructures, even those consisting of centrosymmetric semiconductors, which provides flexibility to develop and optimize electromechanical coupling phenomena. Here, by targeted engineering of the interface symmetry, we achieve piezoelectric phenomena behaving as the electrical analogue of the negative Poisson's ratio. This effect, termed the auxetic piezoelectric effect, exhibits the same sign for the longitudinal (d33) and transverse (d31, d32) piezoelectric coefficients, enabling a simultaneous contraction or expansion in all directions under an external electrical stimulus. The signs of the transverse coefficients can be further tuned via in-plane symmetry anisotropy. The effects exist in a wide range of material systems and exhibit substantial coefficients, indicating potential implications for all-semiconductor actuator, sensor and filter applications.

Management of Pseudophakic Malignant Glaucoma Using Modified Nd:YAG Laser Treatment Methodology Through Surgical Preset Iridectomy.

INTRODUCTION: The use of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser to treat malignant glaucoma (MG) has been described in the literature since the 1980s. However, the technique has been reported to have a short-term effect, with a notable relapse rate. In the present study, we report the efficacy and durability of a modified Nd:YAG laser treatment methodology for treatment of pseudophakic or aphakic MG. METHODS: Patients with chronic angle-closure glaucoma and deemed at high risk of developing post-operative MG received prophylactic peripheral iridectomy during their conventional operation beginning in 2017. When the diagnosis of pseudophakic or aphakic MG was confirmed, a thorough Nd:YAG laser capsulo/zonulo-hyaloido-vitreolysis (CZHV) was performed through iridectomy, along with standardized pre- and post-laser medications. This retrospective case series includes 14 eyes of 11 patients with MG who had surgical preset iridectomy and modified Nd:YAG laser CZHV between 2017 and 2022. Outcome measures included resolution and recurrence of MG and incidence of treatment complications. RESULTS: The mean follow-up was 27.1 ± 15.0 months (range, 12-48). Long-term resolution of MG was obtained in all included eyes at the end of the follow-up. Six eyes (42.9%) achieved long-term resolution with a single Nd:YAG laser intervention. Eight eyes (57.1%) achieved long-term resolution following two to three laser interventions, with two eyes (14.3%) experiencing recurrence. There was no complication during the follow-up. At the final visit, a significant reduction (P = 0.0001) in the mean intraocular pressure (IOP) was observed (13.1 ± 2.8 mmHg) compared to presentation (21.4 ± 6.3 mmHg). CONCLUSION: The modified Nd:YAG laser treatment methodology is a minimally invasive option to manage pseudophakic or aphakic MG with sustained effectiveness. Reduced inflammatory reactions due to prophylactic peripheral iridectomy, rapid diagnosis, and timely treatment initiation have all contributed to the favorable outcomes associated with this modified treatment methodology.

Giant bulk piezophotovoltaic effect in 3R-MoS2.

Given its innate coupling with wavefunction geometry in solids and its potential to boost the solar energy conversion efficiency, the bulk photovoltaic effect (BPVE) has been of considerable interest in the past decade1-14. Initially discovered and developed in ferroelectric oxide materials2, the BPVE has now been explored in a wide range of emerging materials, such as Weyl semimetals9,10, van der Waals nanomaterials11,12,14, oxide superlattices15, halide perovskites16, organics17, bulk Rashba semiconductors18 and others. However, a feasible experimental approach to optimize the photovoltaic performance is lacking. Here we show that strain-induced polarization can significantly enhance the BPVE in non-centrosymmetric rhombohedral-type MoS2 multilayer flakes (that is, 3R-MoS2). This polarization-enhanced BPVE, termed the piezophotovoltaic effect, exhibits distinctive crystallographic orientation dependence, in that the enhancement mainly manifests in the armchair direction of the 3R-MoS2 lattice while remaining largely intact in the zigzag direction. Moreover, the photocurrent increases by over two orders of magnitude when an in-plane tensile strain of ~0.2% is applied, rivalling that of state-of-the-art materials. This work unravels the potential of strain engineering in boosting the photovoltaic performance, which could potentially promote the exploration of novel photoelectric processes in strained two-dimensional layered materials and their van der Waals heterostructures.

Effect of pupil dilation on biometry measurements and intraocular lens power in eyes with high myopia.

Purpose: The present study sought to evaluate the effects of pupil dilation on ocular parameter measurements and intraocular lens (IOL) power calculation using IOLMaster in highly myopic cataract patients. Materials and methods: A total of 233 eyes were included in this prospective study and assigned to four groups based on range of axial length (AL) as follows: group A:26-28 mm, group B:28-30 mm, group C:30-32 mm, and group D:32-36 mm. Flattest and steepest keratometry (K1 and K2), AL, anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WtW) were determined using IOLMaster before and after administration of topical tropicamide. The corresponding IOL powers were calculated using Sanders-Retzlaff-Kraff/theoretical (SRK/T), Haigis, and Barrett Universal II formulas. Results: Variations in AL, K1 and K2 following dilation were not significant (P > 0.05 in all groups). The results showed that ACD increased significantly after dilation (P = 0.000 in all groups), whereas LT decreased significantly after dilation (P = 0.000, 0.000, 0.001, and 0.003). Post-dilation WtW increased significantly in Group A, B, and C (P = 0.001, 0.001, and 0.025) but not in Group D. When IOL power was calculated as a discrete variable, significant differences were observed between pre- and post-dilation IOL power. Conclusion: Pupil dilation in cataract eyes with high myopia does not cause significant changes in AL and K. However, it significantly increases ACD as well as WtW values and significantly decreases the LT value. Surgeons should evaluate the effect of pupil dilation on IOL power prediction as the present findings show extreme cases. Notably, Barrett Universal II formula had the best concordance between different pupil conditions in long eyes.

Bond engineering of molecular ferroelectrics renders soft and high-performance piezoelectric energy harvesting materials.

Piezoelectric materials convert mechanical stress to electrical energy and thus are widely used in energy harvesting and wearable devices. However, in the piezoelectric family, there are two pairs of properties that improving one of them will generally compromises the other, which limits their applications. The first pair is piezoelectric strain and voltage constant, and the second is piezoelectric performance and mechanical softness. Here, we report a molecular bond weakening strategy to mitigate these issues in organic-inorganic hybrid piezoelectrics. By introduction of large-size halide elements, the metal-halide bonds can be effectively weakened, leading to a softening effect on bond strength and reduction in polarization switching barrier. The obtained solid solution C6H5N(CH3)3CdBr2Cl0.75I0.25 exhibits excellent piezoelectric constants (d33 = 367 pm/V, g33 = 3595 × 10-3 Vm/N), energy harvesting property (power density is 11 W/m2), and superior mechanical softness (0.8 GPa), promising this hybrid as high-performance soft piezoelectrics.

Comparison of clinical outcomes of conbercept versus ranibizumab treatment for retinopathy of prematurity: a multicentral prospective randomised controlled trial.

PURPOSE: To compare the recurrence rate and surgical complications of retinopathy of prematurity (ROP) between patients treated with intravitreal injection of conbercept (IVC) and intravitreal injection of ranibizumab (IVR) within 6 months. METHODS: A multicentral prospective, randomised controlled trial was applied from May 2017 to February 2019 for the infants diagnosed as aggressive posterior-ROP, zone I or posterior zone II treatment-requiring ROP by binocular indirect ophthalmoscope and RetCam3. These infants were assigned to randomly receive either intravitreal injection of 0.25 mg conbercept or 0.25 mg ranibizumab. The recurrence rate, fundus fluorescence angiography (FFA) and surgical complications were examined during the follow-up period of 6 months. Recurrent eyes were retreated by laser or another intravitreal injection within the 72 hours. RESULTS: A total of 30 infant patients (60 eyes) underwent IVC and 30 patients (60 eyes) underwent IVR. A total of 10 eyes (16.67%) in the IVC group and 14 eyes (23.34%) in the IVR group developed recurrence. There was no significant statistical difference in the recurrence rate between the two groups (χ2=0.83, p=0.36). The postmenstrual age (PMA) at first injection was (34.60±3.47) weeks in IVC and (35.14±1.76) in IVR group. In recurrent cases, the mean PMA at second treatment were (43.31±3.85) and (43.43±3.89) weeks in the IVC and IVR group, respectively. The period between two treatments was (8.71±6.62) for the IVC and (8.29±2.56) weeks for the IVR group. All these results showed no significant statistical difference between these two groups. The fluorescein leakage were observed in the eyes of recurrent infants by FFA. There were no other complications in the two groups except for complicated cataract in three eyes. CONCLUSION: Both IVC and IVR are effective therapies for the treatment of ROP. Conbercept is a new option for treating ROP.

Surgical membranectomy with modified incision and capsulotomy microscissors for persistent pupillary membrane.

BACKGROUND: To evaluate the visual outcome and complications of surgical membranectomy with modified incision and capsulotomy microscissors in patients with persistent pupillary membrane (PPM). METHODS: We enrolled eight eyes with PPM in six patients and performed surgical membranectomy with modified incision located near the limbus and corresponding to the middle of the densest membrane strands. Strands near the collarette of the iris were then cut using capsulotomy microscissors and thick strands were removed with capculorhexis forceps. Complications during or after surgery were evaluated, and uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were compared pre- and post-surgery. RESULTS: The mean age of the patients at surgery was 9.5±3.4 years (range, 5.3 to 13.8 years). Bilateral PPMs were found in two patients, small anterior capsular cataracts not locating on the visual axis in three eyes, and deprivational amblyopia in four eyes. There were no traumatic cataracts, endophthalmitis, corneal opacities, or other complications in patients during or after modified surgical membranectomy. After a mean follow-up period of 5.8±0.4 (range, 5.0 to 6.0) months, UCVA was significantly improved from 0.23±0.14 to 0.36±0.20(P=0.026), and BCVA was also significantly improved from 0.32±0.22 pre-operatively to 0.56±0.25 post-operatively (P=0.006). CONCLUSIONS: Surgical membranectomy with modified incision and capsulotomy microscissors may be a safe approach to clear the visual axis of patients with PPM. However further treatments were needed in amblyopic eyes after surgery.

Emerging Opportunities for 2D Semiconductor/Ferroelectric Transistor-Structure Devices.

Semiconductor technology, which is rapidly evolving, is poised to enter a new era for which revolutionary innovations are needed to address fundamental limitations on material and working principle level. 2D semiconductors inherently holding novel properties at the atomic limit show great promise to tackle challenges imposed by traditional bulk semiconductor materials. Synergistic combination of 2D semiconductors with functional ferroelectrics further offers new working principles, and is expected to deliver massively enhanced device performance for existing complementary metal-oxide-semiconductor (CMOS) technologies and add unprecedented applications for next-generation electronics. Herein, recent demonstrations of novel device concepts based on 2D semiconductor/ferroelectric heterostructures are critically reviewed covering their working mechanisms, device construction, applications, and challenges. In particular, emerging opportunities of CMOS-process-compatible 2D semiconductor/ferroelectric transistor structure devices for the development of a rich variety of applications are discussed, including beyond-Boltzmann transistors, nonvolatile memories, neuromorphic devices, and reconfigurable nanodevices such as p-n homojunctions and self-powered photodetectors. It is concluded that 2D semiconductor/ferroelectric heterostructures, as an emergent heterogeneous platform, could drive many more exciting innovations for modern electronics, beyond the capability of ubiquitous silicon systems.

Inhibiting the Piezo1 channel protects microglia from acute hyperglycaemia damage through the JNK1 and mTOR signalling pathways.

AIM: Diabetes is a high-risk factor for neurocognitive dysfunction. Diabetic acute hyperglycaemia accompanied by high osmotic pressure can induce immune cell dysfunction, but its mechanism of action in brain microglia remains unclear. This study aimed to evaluate the role of the mechanically sensitive ion channel Piezo1 in the dysfunction of microglia in acute hyperglycaemia. MATERIALS AND METHODS: To construct an in vitro acute hyperglycaemia model using the BV2 microglial cell line, Piezo1 in microglia was inhibited by GsMTx4 and siRNA, and the changes in microglial function were further evaluated. KEY FINDINGS: High concentrations of glucose upregulated the expression of Piezo1, led to weakened cell proliferation and migration, and reduced the immune response to inflammatory stimulating factors (Aß and LPS). Additionally, LPS upregulated Piezo1 in BV2 microglial cultures in vitro. The activation of Piezo1 channels increased the intracellular Ca2+ concentration and reduced the phosphorylation of JNK1 and mTOR. Inhibiting Piezo1 did not affect cell viability at average glucose concentrations but improved acute HCG-induced cell damage and increased the phosphorylation of JNK1 and mTOR, suggesting that the latter modification may be a potential downstream mechanism of Piezo1. SIGNIFICANCE: Piezo1 is necessary for microglial damage in acute hyperglycaemia and may become a promising target to treat hyperglycaemic brain injury.

Changes in the Incidence of Retinopathy of Prematurity in Extremely Low Birth Weight Infants in South China From 2004 to 2018.

PURPOSE: To report the changes in incidence and risk factors of retinopathy of prematurity (ROP) in extremely low birth weight (ELBW) infants over a 15-year period in South China. METHODS: The medical records of ELBW infants were retrospectively reviewed through established database of Shenzhen Screening for ROP Cooperative Group. The incidence and severity of ROP were compared among three successive 5-year periods (P1: 2004-2008, P2: 2009-2013, P3: 2014-2018). Gestational age, birth weight, plurality, mode of delivery and gender were analyzed as risk factors for ROP in ELBW infants. RESULTS: Among the 1099 included ELBW infants, 557 (50.7%) had ROP, and 328 (29.9%) had severe ROP. The highest incidence of ROP (87.5%) and severe ROP (82.5%) were seen in P1. From P2 to P3, the incidence of ROP and severe ROP increased from 45.9% to 50.3% for ROP (P < .05) and from 26.4% to 28.3% for severe ROP (P < .05), respectively. Multivariate logistic regression analysis found only gestational age has a significant effect on the incidence of ROP and severe ROP. CONCLUSIONS: From 2004 to 2018, the incidence of ROP and severe ROP in ELBW infants in South China was 50.7% and 29.9%, respectively. Controlling for the other risk factors, only gestational age was statistically associated with ROP in ELBW infants.

Photovoltaic and flexible deep ultraviolet wavelength detector based on novel ß-Ga2O3/muscovite heteroepitaxy.

Flexible and self-powered deep ultraviolet (UV) photodetectors are pivotal for next-generation electronic skins to enrich human life quality. The fabrication of epitaxial ß-Ga2O3 thin films is challenging on flexible substrates due to high-temperature growth requirements. Herein, ß-Ga2O3 ([Formula: see text] 0 1) films are hetero-epitaxially grown on ultra-thin and environment-friendly muscovite mica which is the first time ß-Ga2O3 epitaxy growth on any flexible substrate. Integration of Gallium oxide with muscovite enables high-temperature processing as well as excellent flexibility compared to polymer substrates. Additionally, the metal-semiconductor-metal (MSM) photodetector on ß-Ga2O3 layer shows an ultra-low dark current of 800 fA at zero bias. The photovoltaic peak responsivity of 11.6 µA/W is obtained corresponding to very weak illumination of 75 µW/cm2 of 265 nm wavelength. Thermally stimulated current (TSC) measurements are employed to investigate the optically active trap states. Among these traps, trap with an activation energy of 166 meV dominates the persistence photocurrent in the devices. Finally, photovoltaic detectors have shown excellent photocurrent stability under bending induced stress up to 0.32%. Hence, this novel heteroepitaxy opens the new way for flexible deep UV photodetectors.

Piezoelectric and pyroelectric effects induced by interface polar symmetry.

Interfaces in heterostructures have been a key point of interest in condensed-matter physics for decades owing to a plethora of distinctive phenomena-such as rectification1, the photovoltaic effect2, the quantum Hall effect3 and high-temperature superconductivity4-and their critical roles in present-day technical devices. However, the symmetry modulation at interfaces and the resultant effects have been largely overlooked. Here we show that a built-in electric field that originates from band bending at heterostructure interfaces induces polar symmetry therein that results in emergent functionalities, including piezoelectricity and pyroelectricity, even though the component materials are centrosymmetric. We study classic interfaces-namely, Schottky junctions-formed by noble metal and centrosymmetric semiconductors, including niobium-doped strontium titanium oxide crystals, niobium-doped titanium dioxide crystals, niobium-doped barium strontium titanium oxide ceramics, and silicon. The built-in electric field in the depletion region induces polar structures in the semiconductors and generates substantial piezoelectric and pyroelectric effects. In particular, the pyroelectric coefficient and figure of merit of the interface are over one order of magnitude larger than those of conventional bulk polar materials. Our study enriches the functionalities of heterostructure interfaces, offering a distinctive approach to realizing energy transduction beyond the conventional limitation imposed by intrinsic symmetry.

Comparison of OCT angiography in children with a history of intravitreal injection of ranibizumab versus laser photocoagulation for retinopathy of prematurity.

PURPOSE: To compare the foveal microvascular structure characteristics in children with a history of intravitreal injection of ranibizumab (IVR) versus laser photocoagulation (LP) for retinopathy of prematurity by optical coherence tomography angiography (OCTA). METHODS: In this cross-sectional study, a total of 17 children (28 eyes) underwent IVR and 20 children (37 eyes) underwent LP were recruited. The age of doing OCTA examination of the two groups are 5.4±1.1 years and 6.3±1.8 years, respectively (p=0.07). Spectral-domain OCTA was performed for all the eyes with a scan size of 3×3 mm. The data of the superficial retinal layer were analysed. The foveal avascular zone (FAZ) and vessel density (including vessel length density (VLD) and perfusion density (PD)) were measured using the software of OCTA (Cirrus AngioPlex 5000, Carl Zeiss, Meditec, Dubin, California, USA). The central foveal thicknesses (CFT) were measured by cross-sectional OCT. RESULTS: In the central fovea, the retinal VLD and PD of patients with IVR were 13.82±2.99 mm/mm2 and 0.25±0.05 mm2/mm2, respectively, which were significantly lower than those of the LP group (15.64±2.71 mm/mm2 and 0.28±0.05 mm2/mm2, p=0.01 and p=0.006). The FAZ area of patients with IVR and LP were 0.13±0.09 mm2 and 0.09±0.07 mm2, respectively (p=0.048). The CFT of patients with IVR and LP were 200.7±16.7 µm and 220.9±22.7 µm, respectively (p<0.01). The logarithm of the minimal angle of resolution best-corrected visual acuity of patients with IVR and LP were 0.2±0.1 and 0.1±0.1, respectively (p=0.01). There was no significant difference in the parafoveal and foveal VLD and PD, FAZ morphological index and spherical equivalent refraction (SER) between the two groups. CONCLUSION: The IVR might contribute to microvascular changes in the macular zone, such as reducing the central foveal VLD and PD, while the LP might contribute to microstructural changes, such as smaller FAZ and thicker CFT.

Targeted Blood Metabolomic Study on Retinopathy of Prematurity.

Purpose: This study aims at exploring alterations of major metabolites and metabolic pathways in retinopathy of prematurity (ROP) infants and identifying biomarkers that may merit early diagnosis of ROP. Methods: We analyzed targeted metabolites from 81 premature infants (<34 weeks of gestational age), including 40 ROP cases (15 males and 25 females, birth weight 1.263 ± 0. 345 kg, gestational age 31.20 ± 4.62 weeks) and 41 cases (30 males, 11 females, birth weight 1.220 ± 0.293 kg, gestational age 30.96 ± 4.17 weeks) of well-matched non-ROP controls. Metabolites were measured by ultra-performance liquid chromatography-tandem mass spectrometry. Standard multivariate and univariate analysis was performed to interpret metabolomic results. Results: Glycine, glutamate, leucine, serine, piperidine, valine, tryptophan, citrulline, malonyl carnitine (C3DC), and homocysteine were identified as the top discriminant metabolites. In particular, discriminant concentrations of C3DC and glycine were also confirmed by univariate analysis as statistically significant different between ROP and non-ROP infants. Conclusions: This study gained an insight into the metabolomic aspects of ROP development. We suggest that higher blood levels of C3DC and glycine can be promising biomarkers to predict the occurrence, but not the severity of ROP.

Evaluation of Corneal Curvature and Astigmatism in Patients with Persistent Pupillary Membrane by Partial Coherence Interferometry Measurements.

PURPOSE: To evaluate and compare the corneal curvature and astigmatism in patients with persistent pupillary membrane (PPM) and healthy controls by partial coherence interferometry. METHODS: This study included 14 eyes (9 patients) with PPM and 16 eyes (16 subjects) without PPM or other ocular disease, which were age and gender matched. The horizontal corneal radius of curvature (hCRC), vertical CRC (vCRC), average CRC (aveCRC), corneal astigmatic vectors (CAV), and axis were recorded using partial coherence interferometry. Uncorrected visual acuity and best corrected visual acuity (BCVA) were also recorded using a logMAR chart. RESULTS: In the PPM group, the vCRC (45.46 ± 0.52 D) was significantly larger than that in the control group (44.05 ± 0.24 D) (p = 0.009). The aveCRC in the PPM group (43.90 ± 0.46 D) was also significantly larger than that in the control group (43.34 ± 0.23 D) (p = 0.018). In the PPM group, the hCRC (42.35 ± 0.41 D) was significantly smaller than that in the control group (42.63 ± 0.24 D) (p = 0.049). The astigmatisms were with-the-rule in both groups. The absolute value of CAV in PPM group (3.17 ± 0.23 D) was significantly higher than that of control (1.36 ± 0.09 D) (p = 0.001). BCVA (0.42 ± 0.08) in PPM group was significantly worse than that in control (0.90 ± 0.03) (p = 0.009). CONCLUSIONS: The larger vertical and smaller horizontal corneal curvature resulted in higher corneal astigmatism with the rule, which is a characteristic feature in patients with PPM. More attention should be paid to astigmatism status and correction treatment for these patients.

Artificial Optoelectronic Synapses Based on Ferroelectric Field-Effect Enabled 2D Transition Metal Dichalcogenide Memristive Transistors.

Neuromorphic visual sensory and memory systems, which can perceive, process, and memorize optical information, represent core technology for artificial intelligence and robotics with autonomous navigation. An optoelectronic synapse with an elegant integration of biometric optical sensing and synaptic learning functions can be a fundamental element for the hardware-implementation of such systems. Here, we report a class of ferroelectric field-effect memristive transistors made of a two-dimensional WS2 semiconductor atop a ferroelectric PbZr0.2Ti0.8O3 (PZT) thin film for optoelectronic synaptic devices. The WS2 channel exhibits voltage- and light-controllable memristive switching, dependent on the optically and electrically tunable ferroelectric domain patterns in the underlying PZT layer. These devices consequently show the emulation of optically driven synaptic functionalities including both short- and long-term plasticity as well as the implementation of brainlike learning rules. Integration of these rich synaptic functionalities into one single artificial optoelectronic device could allow the development of future neuromorphic electronics capable of optical information sensing and learning.

Strain-gradient mediated local conduction in strained bismuth ferrite films.

It has been recently shown that the strain gradient is able to separate the light-excited electron-hole pairs in semiconductors, but how it affects the photoelectric properties of the photo-active materials remains an open question. Here, we demonstrate the critical role of the strain gradient in mediating local photoelectric properties in the strained BiFeO3 thin films by systematically characterizing the local conduction with nanometre lateral resolution in both dark and illuminated conditions. Due to the giant strain gradient manifested at the morphotropic phase boundaries, the associated flexo-photovoltaic effect induces on one side an enhanced photoconduction in the R-phase, and on the other side a negative photoconductivity in the morphotropic [Formula: see text]-phase. This work offers insight and implication of the strain gradient on the electronic properties in both optoelectronic and photovoltaic devices.