Detection of aqueous VEGF concentrations before and after intravitreal injection of anti-VEGF antibody using low-volume sampling paper-based ELISA

Dysregulation of histone deacetylases in ocular diseases

Ocular diseases are a growing global concern and have a significant impact on the quality of life. Cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy are the most prevalent ocular diseases. Their prevalence and the global market size are also increasing. However, the available pharmacotherapy is currently limited. These diseases share common pathophysiological features, including neovascularization, inflammation, and/or neurodegeneration. Histone deacetylases (HDACs) are a class of enzymes that catalyze the removal of acetyl groups from lysine residues of histone and nonhistone proteins. HDACs are crucial for regulating various cellular processes, such as gene expression, protein stability, localization, and function. They have also been studied in various research fields, including cancer, inflammatory diseases, neurological disorders, and vascular diseases. Our study aimed to investigate the relationship between HDACs and ocular diseases, to identify a new strategy for pharmacotherapy. This review article explores the role of HDACs in ocular diseases, specifically focusing on diabetic retinopathy, age-related macular degeneration, and retinopathy of prematurity, as well as optic nerve disorders, such as glaucoma and optic neuropathy. Additionally, we explore the interplay between HDACs and key regulators of fibrosis and angiogenesis, such as TGF-β and VEGF, highlighting the potential of targeting HDAC as novel therapeutic strategies for ocular diseases.

Effect of Conbercept on Corneal Neovascularization in a Rabbit Model

OBJECTIVE

To study the efficacy of Conbercept for the treatment of corneal neovascularization (NV) in a rabbit model.

METHODS

NV was induced by placing sutures. Eight rabbits were used as a control. The other 136 rabbits were randomly divided into two equal groups, and 68 rabbits in each group were divided into four subgroups and given different treatments. Time-course photographs, histological examination, and enzyme-linked immunoassay ELISA analysis for vascular endothelial growth factor were performed at weeks 1, 2, and 3 after injection placement.

RESULTS

At weeks 1, 2, and 3 after injection placement, there was less expression of corneal NV and VEGF in the conbercept-treated groups than in the saline-treated control groups and less corneal NV and VEGF were expressed in the early treatment group than in the late treatment group. At weeks 2 and 3 after injection, there were fewer corneal NV (length and area) in the early intrastromal injection group with conbercept than in the early subconjunctival injection group with conbercept and a smaller diameter of corneal NV than in the late intrastromal injection group treated with conbercept. Histological examination showed a smaller diameter of corneal NV in all eyes in conbercept-treated groups 1 w after injection than before injection. Treatment with subconjunctival injection with conbercept led to a larger diameter at weeks 2 and 3 than at week 1.

CONCLUSIONS

Subconjunctival and intrastromal administrations of conbercept effectively inhibit corneal NV in rabbits, and the latter has the better effect. The effect is the best in the group with cornea intrastromal injection of conbercept 1 w after suture. Early administration of conbercept may successfully inhibit corneal NV in an animal model.

A single intravenous injection of cyclosporin A-loaded lipid nanocapsules prevents retinopathy of prematurity

Retinopathy of prematurity (ROP) is a retinal disease that threatens the vision of prematurely born infants. Severe visual impairment up to complete blindness is caused by neovascularization and inflammation, progressively destroying the immature retina. ROP primarily affects newborns in middle- and low-income countries with limited access to current standard treatments such as intraocular drug injections and laser- or cryotherapy. To overcome these limitations, we developed a nanotherapeutic that effectively prevents ROP development with one simple intravenous injection. Its lipid nanocapsules transport the antiangiogenic and anti-inflammatory cyclosporin A efficiently into disease-driving retinal pigment epithelium cells. In a mouse model of ROP, a single intravenous injection of the nanotherapeutic prevented ROP and led to normal retinal development by counteracting neovascularization and inflammation. This nanotherapeutic approach has the potential to bring about a change of paradigm in ROP therapy and prevent millions of preterm born infants from developing ROP.

Double Signal Amplification Strategy for Dual-Analyte Fluorescent Aptasensors for Visualizing Cancer Biomarker Proteins

The simultaneous analysis of diversified biomarkers with high sensitivity and in a point-of-care (POC) manner is of great significance for facile and early cancer diagnosis. Herein, we develop a target amplification-assisted ratiometric fluorescence assay (TARFA) platform integrating the dual-amplification strategy and colorimetric readout technology for sensitive and specific detection of two malignancy-associated biomarkers. Meanwhile, the NIR-excited alkaline-earth sulfide nanodots (ASNDs) with an ultrasmall (<10 nm) diameter and tunable emission wavelength are employed to replace commonly UV/visible light-excited fluorescent labels to minimize background interference from the sample matrix. Unique advantages of the ASNDs, together with superiority of consecutive signal amplification of enzymatic target recycling (ETR) and hybridization chain reaction (HCR), realize the pg/mL-range detection limit in specifically recognizing the vascular endothelial growth factor (VEGF) and soluble interleukin-6 receptors (sIL-6R). The combination detection of the dual analyte exhibits an improved sensitivity for cancer diagnosis. The addition of the target biomarkers leads to an increasingly ratiometric RGB signal, and quantification based on the ratio-dependent signal is more reliable rather than measuring the absolute RGB signals. Moreover, perceptible color transformation makes the TARFA platform competent for visual analysis of the target analytes as convenient as reading the pH indicator strip, and hue-based image analysis also improves the method with fine precision by quantitatively identifying the visual color. This work provides a new kind of NIR-excited aptasensing platform with a low detection limit, high throughput, and great portability, which also highlights the potential of the ASNDs in biomolecular fluorescent labeling.

A Multi-Epitope Fusion Protein-Based p-ELISA Method for Diagnosing Bovine and Goat Brucellosis

In recent years, the incidence of brucellosis has increased annually, causing tremendous economic losses to animal husbandry in a lot of countries. Therefore, developing rapid, sensitive, and specific diagnostic techniques is critical to control the spread of brucellosis. In this study, bioinformatics technology was used to predict the B cell epitopes of the main outer membrane proteins of Brucella, and the diagnostic efficacy of each epitope was verified by an indirect enzyme-linked immunosorbent assay (iELISA). Then, a fusion protein containing 22 verified epitopes was prokaryotically expressed and used as an antigen in paper-based ELISA (p-ELISA) for serodiagnosis of brucellosis. The multi-epitope-based p-ELISA was evaluated using a collection of brucellosis-positive and -negative sera collected from bovine and goat, respectively. Receiver operating characteristic (ROC) curve analysis showed that the sensitivity and specificity of detection-ELISA in diagnosing goat brucellosis were 98.85 and 98.51%. The positive and the negative predictive values were 99.29 and 98.15%, respectively. In diagnosing bovine brucellosis, the sensitivity and specificity of this method were 97.85 and 96.61%, with the positive and negative predictive values being identified as 98.28 and 97.33%, respectively. This study demonstrated that the B cell epitopes contained in major antigenic proteins of Brucella can be a very useful antigen source in developing a highly sensitive and specific method for serodiagnosis of brucellosis.

Facile open-well immunofluorescence enhancement with coplanar-electrodes-enabled optoelectrokinetics and magnetic particles

Electrokinetic manipulation has been proven powerful in enhancing the sensing capability of general-purpose biochips. However, the close-form configuration of biochips and the required use of low electric conductivity limit their practicability. In this study, an open-well microfluidic system facilitated with coplanar-electrodes-enabled optoelectrokinetic concentration and magnetic particles were therefore developed to overcome these challenges. The open side achieves optoelectrokinetic manipulation for biosignal enhancement, enabling free manual operations. Magnetic particles were employed in immunoassays to facilitate the rapid onsite separation of targets. A common cytokine biomarker found in many diseases, that is, tumor necrosis factor alpha (TNF-α), was used for assessing the immunosensing system. In addition to the benefits inherited from the immunoassays, the fluorescent signal enhanced by the optoelectrokinetic technique also featured rapid enhancement in 1 min and a limit of detection of as low as 2.9 pg/mL. The open-well architecture allowed the entire immunosensing process to be completed on site without frequent off-site washing. For a practical test, the TNF-α in human tear fluids was measured by the developed device and validated with a standard enzyme-linked immunosorbent assay (ELISA). The data show consistency in terms of trend. The developed open-well optoelectrokinetic device provides an insight into future facile clinical diagnoses. By simply modifying the surface linkers on the magnetic particles, the technique can be further extended to more other trace biomarker detections.

Durability of VEGF Suppression With Intravitreal Aflibercept and Brolucizumab: Using Pharmacokinetic Modeling to Understand Clinical Outcomes

Purpose

To investigate whether vascular endothelial growth factor (VEGF)–suppression durations contribute to our understanding of clinical trial outcomes by simulating vitreous molar concentrations (C_vm) of intravitreal aflibercept (IVT-AFL) and brolucizumab (IVT-BRO) using pharmacokinetic (PK) modeling.

Methods

A PK model simulated C_vm after single-dose IVT-AFL, IVT-BRO, and ranibizumab (IVT-RAN), and extrapolated intraocular VEGF-suppression thresholds and durations. Vitreous PK after multidose regimens used in studies of IVT-AFL versus IVT-BRO were simulated and compared with best-corrected visual acuity (BCVA) data.

Results

C_vm peaked higher (C_max) and decreased more quickly to the VEGF-suppression threshold and minimum (C_min) levels with IVT-BRO than with IVT-AFL, consistent with their molar doses calculated using molecular weights and vitreous half-lives (26 kDa and 115 kDa; 4.4–5.1 and 9.1–11 days, respectively). The mean VEGF suppression durations were 71 days for IVT-AFL 2 mg and 51 (48–59) days for IVT-BRO 6 mg. Based on dosing in OSPREY (matched dosing to week [w]32 for both agents; thereafter, IVT-AFL every eight weeks [q8w] and IVT-BRO q12w for the last two doses [w32→w44 and w44→w56]), IVT-BRO showed wider C_max-C_min fluctuations than IVT-AFL. The IVT-BRO C_min fell below the VEGF-suppression threshold at timepoints near w56, when decreases in BCVA were also observed. The IVT-AFL vitreous C_min remained above the suppression threshold through w56, where BCVA gains were maintained.

Conclusions

The PK-modeled mean VEGF-suppression duration for IVT-BRO was substantially shorter than that published for IVT-AFL and may not be sufficient to effectively suppress VEGF throughout q12w dosing.

Translational Relevance

The PK modeling suggests that more patients may be maintained on ≥q12w dosing with IVT-AFL than with IVT-BRO.

Small-volume detection: platform developments for clinically-relevant applications

Biochemical analysis of human body fluids is a frequent and fruitful strategy for disease diagnosis. Point-of-care (POC) diagnostics offers the tantalizing possibility of providing rapid diagnostic results in non-laboratory settings. Successful diagnostic testing using body fluids has been reported on in the literature; however, small-volume detection devices, which offer remarkable advantages such as portability, inexpensiveness, capacity for mass production, and tiny sample volume requirements have not been thoroughly discussed. Here, we review progress in this research field, with a focus on developments since 2015. In this review article, we provide a summary of articles that have detailed the development of small-volume detection strategies using clinical samples over the course of the last 5 years. Topics covered include small-volume detection strategies in ophthalmology, dermatology or plastic surgery, otolaryngology, and cerebrospinal fluid analysis. In ophthalmology, advances in technology could be applied to examine tear or anterior chamber (AC) fluid for glucose, lactoferrin, interferon, or VEGF. These approaches could impact detection and care for diseases including diabetic mellitus, dry-eye disease, and age-related maculopathy. Early detection and easy monitoring are critical approaches for improving overall care and outcome. In dermatology or plastic surgery, small-volume detection strategies have been applied for passive or interactive wound dressing, wound healing monitoring, and blister fluid analysis for autoimmune disease diagnosis. In otolaryngology, the analysis of nasal secretions and mucosa could be used to differentiate between allergic responses and infectious diseases. Cerebrospinal fluid analysis could be applied in neurodegenerative diseases, central neural system infection and tumor diagnosis. Other small-volume fluids that have been analyzed for diagnostic and monitoring purposes include semen and cervico-vaginal fluids. We include more details regarding each of these fluids, associated collection and detection devices, and approaches in our review.

Changes in aqueous and vitreous inflammatory cytokine levels in neovascular age-related macular degeneration: a systematic review and meta-analysis

Inflammatory cytokines are involved in the pathogenesis of neovascular age-related macular degeneration (nAMD) and have been shown to be useful as diagnostic and predictive biomarkers. Given the heterogeneity of data within the literature, we aimed to quantitatively summarize data related to inflammatory cytokines in nAMD. A systematic search without year limitation was performed up to 13 April 2020. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with nAMD. Data were extracted from 95 studies that encompassed 3105 study eyes with nAMD and 1209 control eyes. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with nAMD and controls. Among the 4314 eyes in 95 studies, aqueous concentrations (standard mean difference, 95% confidence interval and p-value) of MCP-1 (0.43, 0.09 to 0.77 and p = 0.01), MIG (0.63, 0.31 to 0.94 and p = 0.0001), TGF-β (0.45, 0.07 to 0.82 and p = 0.02) and VEGF (0.64, 0.31 to 0.98 and p = 0.0001) were significantly higher in patients with nAMD compared to healthy controls. No differences, failed sensitivity analyses or insufficient data were found between patients with nAMD and healthy controls for the concentrations of the remaining cytokines and with all vitreous samples. Previous studies had shown conflicting associations with nAMD for all 27 cytokines assessed. Our analysis indicates multiple candidate cytokines other than VEGF that are implicated in nAMD and adds clarity to the previous literature. This will help focus translational research in nAMD investigating biomarkers and therapeutic targets.

Turntable Paper-Based Device to Detect Escherichia coli

Escherichia coli has been known to cause a variety of infectious diseases. The conventional enzyme-linked immunosorbent assay (ELISA) is a well-known method widely used to diagnose a variety of infectious diseases. This method is expensive and requires considerable time and effort to conduct and complete multiple integral steps. We previously proposed the use of paper-based ELISA to rapidly detect the presence of E. coli. This approach has demonstrated utility for point-of-care (POC) urinary tract infection diagnoses. Paper-based ELISA, while advantageous, still requires the execution of several procedural steps. Here, we discuss the design and experimental implementation of a turntable paper-based device to simplify the paper-based ELISA protocols for the detection of E. coli. In this process, antibodies or reagents are preloaded onto zones of a paper-based device and allowed to dry before use. We successfully used this device to detect E. coli with a detection limit of 10⁵ colony-forming units (colony-forming unit [CFU])/mL.

Fibrotic Changes and Endothelial-to-Mesenchymal Transition Promoted by VEGFR2 Antagonism Alter the Therapeutic Effects of VEGFA Pathway Blockage in a Mouse Model of Choroidal Neovascularization

Many patients with wet age-related macular degeneration do not respond well to anti- vascular endothelial growth factor A (VEGFA) therapy for choroidal neovascularization (CNV), and the efficacy of anti-VEGFA decreases over time. We investigated the hypothesis that fibrotic changes, in particular via endothelial-to-mesenchymal transition (EndoMT), play a role in CNV and alter the therapeutic effects of VEGFA pathway blockage. Induction of EndoMT of primary human retinal endothelial cells led to a significantly reduced response to VEGFA at the level of gene expression, cellular proliferation, migration, and tube formation. Suppression of EndoMT restored cell responsiveness to VEGFA. In a mouse model of spontaneous CNV, fibrotic changes and EndoMT persisted as the CNV lesions became more established over time. VEGFA receptor-2 (VEGFR2) antagonism further induced fibrosis and EndoMT in the CNV. The combination of VEGFR2 antagonism and fibrosis/EndoMT inhibition was more effective than either individual treatment in reducing CNV. Our data indicate that fibrosis and EndoMT are involved in the progression of CNV, are exacerbated by VEGFR2 inhibition, and could provide an explanation for the reduced efficacy of anti-VEGFA treatment over time.

Ultrasensitive optofluidic enzyme-linked immunosorbent assay by on-chip integrated polymer whispering-gallery-mode microlaser sensors

Optical whispering-gallery-mode (WGM) microcavities offer great promise in ultrasensitive biosensors because of their unique ability to enable resonant recirculation of light to achieve strong light-matter interactions in microscale volumes. However, it remains a challenge to develop cost-effective, high-performance WGM microcavity-based biosensing devices for practical disease diagnosis applications. In this paper, we present an optofluidic chip that is integrated with directly-printed, high-quality-factor (Q) polymer WGM microlaser sensors for ultrasensitive enzyme-linked immunosorbent assay (ELISA). Optical 3D μ-printing technology based on maskless ultraviolet lithography is developed to rapidly fabricate high-Q suspended-disk WGM microcavities. After deposition with a thin layer of optical gain material, low-threshold WGM microlasers are fabricated and then integrated together with optical fibres upon a microfluidic chip to achieve an optofluidic device. With flexible microfluidic technology, on-chip, integrated, WGM microlasers are further modified in situ with biomolecules on surface for highly selective biomarker detection. It is demonstrated that such an optofluidic biochip can measure horseradish peroxidase (HRP)-streptavidin, which is a widely used catalytic molecule in ELISA, via chromogenic reaction at the concentration level of 0.3 ng mL-1. Moreover, it enables on-chip optofluidic ELISA of the disease biomarker vascular endothelial growth factor (VEGF) at the extremely low concentration level of 17.8 fg mL-1, which is over 2 orders of magnitude better than the ability of current commercial ELISA kits.

microRNA Expression Profile in the Vitreous of Proliferative Diabetic Retinopathy Patients and Differences from Patients Treated with Anti-VEGF Therapy

Purpose

microRNAs (miRNAs) mediate the pathological mechanisms of diabetic retinopathy. In this study, we compared miRNA expression profiles in the vitreous between patients with proliferative diabetic retinopathy (PDR) and patients with a macular hole as non-diabetic controls, and between PDR patients treated with anti-vascular endothelial growth factor (VEGF) therapy and untreated PDR patients.

Methods

Vitreous samples of non-diabetic and PDR patients were screened for miRNAs with quantitative polymerase chain reaction (qPCR) panels. miRNA candidates were validated in vitreous samples of a second, independent cohort. In addition, the effect of anti-VEGF therapy was investigated in the vitreous of a third study population consisting of PDR patients who had not received anti-VEGF therapy and PDR patients who had received preoperative anti-VEGF therapy.

Results

During screening, seven miRNAs were found to be significantly higher in the vitreous of PDR patients, whereas two miRNAs were found to be significantly lower compared with non-diabetic controls. Validating the expression of these miRNAs in a second cohort resulted in the identification of six miRNAs that were expressed at significantly higher rates in the vitreous of PDR patients: hsa-miR-20a-5p, hsa-miR-23b-3p, hsa-miR-142-3p, hsa-miR-185-5p, hsa-miR-326, and hsa-miR-362-5p. Among these six miRNAs, hsa-miR-23b-3p levels were lower in the anti-VEGF-treated group of PDR patients compared with untreated PDR patients.

Conclusions

In this study, we identified six miRNAs that are expressed more highly in PDR patients and one miRNA that is expressed at a lower levels in anti-VEGF-treated PDR patients.

Translational Relevance

miRNAs identified in the vitreous of PDR patients may improve our understanding of the mechanisms leading to PDR.

Enhanced performance of an electrochemical aptasensor for real-time detection of vascular endothelial growth factor (VEGF) by nanofabrication and ratiometric measurement

Achieving a biosensing interface without baseline drift caused by variables in matrix samples is essential for real-time detection of analytes. In this study, we developed a molecular beacon based electrochemical aptasensor to realize the ratiometric signal quantification of VEGF in serum by surface modification of nanocomposites of graphene oxide/methylene blue (GO/MB) and AuNPs followed by the attachment of ferrocene-labeled aptamer (aptamer-Fc) against VEGF. The presence of VEGF can trigger the configuration change of aptamer-Fc, resulting in the redox probe Fc being far away from the electrode surface to attenuate the electrochemical communication between electrode and Fc. Meanwhile, signal of MB also decreased due to the impediment of aptamer-Fc to electron transfer passage. The achieved GC-rGO/MB-AuNPs-aptamer-Fc sensing interface was successfully used for the sensitive detection of VEGF in real-time with a linear detection range 2-500 pg mL^-1 and detection limit of 0.1 pg mL^-1 based on ratiometric dual signal (Fc and MB) read-out. It was observed loading MB and AuNPs to the GO based sensing interface was favorable to enhance the analytical performance in terms of sensitivity and capability to effectively eliminate background interference. This electrochemical aptasensor provides a universal and reliable biosensing platform which is potential for real-time and sensitive tracking of various cytokines in vivo.

Paper-Based Detection Device for Alzheimer's Disease-Detecting β-amyloid Peptides (1-42) in Human Plasma

The diagnosis of Alzheimer's disease (AD) is frequently missed or delayed in clinical practice. To remedy this situation, we developed a screening, paper-based (P-ELISA) platform to detect β-amyloid peptide 1-42 (Aβ42) and provide rapid results using a small volume, easily accessible plasma sample instead of cerebrospinal fluid. The protocol outlined herein only requires 3 μL of sample per well and a short operating time (i.e., only 90 min). The detection limit of Aβ42 is 63.04 pg/mL in a buffer system. This P-ELISA-based approach can be used for early, preclinical stage AD screening, including screening for amnestic mild cognitive impairment (MCI) due to AD. It may also be used for treatment and stage monitoring purposes. The implementation of this approach may provide tremendous impact for an afflicted population and may well prompt additional and expanded efforts in both academic and commercial communities.

Two Potential Clinical Applications of Origami-Based Paper Devices

Detecting small amounts of analyte in clinical practice is challenging because of deficiencies in specimen sample availability and unsuitable sampling environments that prevent reliable sampling. Paper-based analytical devices (PADs) have successfully been used to detect ultralow amounts of analyte, and origami-based PADs (O-PADs) offer advantages that may boost the overall potential of PADs in general. In this study, we investigated two potential clinical applications for O-PADs. The first O-PAD we investigated was an origami-based enzyme-linked immunosorbent assay (ELISA) system designed to detect different concentrations of rabbit IgG. This device was designed with four wing structures, each of which acted as a reagent loading zone for pre-loading ELISA reagents, and a central test sample loading zone. Because this device has a low limit of detection (LOD), it may be suitable for detecting IgG levels in tears from patients with a suspected viral infection (such as herpes simplex virus (HSV)). The second O-PAD we investigated was designed to detect paraquat levels to determine potential poisoning. To use this device, we sequentially folded each of two separate reagent zones, one preloaded with NaOH and one preloaded with ascorbic acid (AA), over the central test zone, and added 8 µL of sample that then flowed through each reagent zone and onto the central test zone. The device was then unfolded to read the results on the test zone. The three folded layers of paper provided a moist environment not achievable with conventional paper-based ELISA. Both O-PADs were convenient to use because reagents were preloaded, and results could be observed and analyzed with image analysis software. O-PADs expand the testing capacity of simpler PADs while leveraging their characteristic advantages of convenience, cost, and ease of use, particularly for point-of-care diagnosis.

A Smartphone-based Diffusometric Immunoassay for Detecting C-Reactive Protein

In this study, we developed a portable smartphone-based diffusometry for analyzing the C-reactive protein (CRP) concentration. An optimized fluorescence microscopic add-on system for a smartphone was used to image the 300 nm fluorescent beads. Sequential nanobead images were recorded for a period and the image data were used for fluorescence correlation spectrometric (FCS) analysis. Through the analysis, the nanobeads' diffusion coefficient was obtained. Further, the diffusion coefficients of the anti-CRP-coated nanobeads, which were suspended in the samples with various CRP concentrations, were estimated using smartphone-based diffusometry. After 10 min of reaction, the anti-CRP-coated nanobeads in a higher CRP concentration solution led to a lower diffusion coefficient. Based on the experiments, a linear sensing range of 1~8 µg/mL was found.

Robust Covalent Coupling Scheme for the Development of FRET Aptasensor based on Amino-Silane-Modified Graphene Oxide

In recent years, numerous aptamers have been physisorbed on graphene oxide (GO) to develop fluorescence resonance energy transfer-based aptasensors using the fluorescence quenching property of GO. However, physisorbed aptasensors show poor signal reversibility and reproducibility as well as nonspecific probe displacement, and thereby are not suitable for many analytical applications. To overcome these problems when working with complex biological samples, we developed a facile and robust covalent surface functionalization technique for GO-based fluorescent aptasensors using a well-studied adenosine triphosphate binding aptamer (ABA). In the scheme, GO is first modified with amino-silane, and further with glutaraldehyde to create available carbonyl groups for the covalent attachment of a fluorophore and an amino dual modified ABA. The surface modification method was characterized by ζ-potential, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The linearity, sensitivity, selectivity, and reversibility of the resulting GO-based covalent aptasensor was determined and systematically compared with the physisorbed aptasensor. Although both sensors showed similar performance in terms of sensitivity and linearity, better selectivity and higher resistance to nonspecific probe displacement was achieved with the developed covalent ABA sensor. The surface modification technique developed here is independent of the aptamer sequence, and therefore could be used universally for different analytical applications simply by changing the aptamer sequence for the target biomolecule.

Intravitreal aflibercept versus bevacizumab for treatment of myopic choroidal neovascularization

The authors performed a retrospective and comparative study to compare the efficacy of intravitreal aflibercept and bevacizumab for patients with myopic choroidal neovascularization (mCNV). The patients with treatment-naïve mCNV received 1 + PRN intravitreal bevacizumab from March 2008 to February 2013, while from March 2013 to July 2016 patients were treated by 1 + PRN intravitreal aflibercept, all with monthly follow-up for 12 months. Primary outcome measures included change in central foveal thickness (CFT) in 1 mm by spectral-domain optic coherence tomography, and best corrected visual acuity (BCVA) at month 12. Complications after injections were recorded. The intra-group changes in CFT and BCVA were compared with Wilcoxon signed rank test, the between-group difference compared with Wilcoxon rank sum test. Fisher's exact test was used for categorical comparison between groups. Seventy-eight eyes of 78 patients were collected. There were 42 eyes in bevacizumab group, with mean age of 53.2 ± 5.4 years and 27 female patients of them. The mean BCVA significantly improved from baseline 0.56 ± 0.35 logMAR to 0.35 ± 0.35 logMAR at Month 12 after bevacizumab treatment (p < 0.001). The mean CFT significantly decreased from baseline 315.3 ± 25.6 μm to 253.7 ± 24.4 μm at Month 12 following intravitreal bevacizumab (p < 0.001). There were 36 eyes in aflibercept group, with mean age of 52.8 ± 6.8 years and 24 female patients of them. The mean BCVA significantly improved from baseline 0.61 ± 0.47 logMAR to 0.38 ± 0.41 logMAR at Month 12 after aflibercept treatment (p < 0.001). The mean CFT significantly decreased from baseline 328.2 ± 19.8 μm to 241.8 ± 27.2 μm at Month 12 following intravitreal aflibercept (p < 0.001). The baseline demographics, lens status, axial length, refractive errors, duration of symptoms, BCVA, and CFT did not differ significantly between groups (p > 0.05). There was no significant difference between bevacizumab and aflibercept groups in BCVA and CFT from Month 1 to Month 12 (p > 0.05). Injection number of aflibercept was 2.11 ± 0.41, less than that of bevacizumab (3.23 ± 0.38) during 12-month period (p = 0.01). There were no systemic thromboembolic event, elevated intraocular pressure, retinal detachment, or infectious endophthalmitis following injections in both groups. We concluded that both aflibercept and bevacizumab can effectively treat choroidal neovascularization in high myopes. Intravitreal aflibercept had similar efficacy but less treatment number than bevacizumab for mCNV during 12-month period.

Paper-Based Microfluidic Platforms for Understanding the Role of Exosomes in the Pathogenesis of Major Blindness-Threatening Diseases

Emerging roles of exosomes in the pathogenesis of major blindness-threatening diseases, such as age-related macular degeneration, glaucoma, and corneal dystrophy, were discovered by aqueous humor analysis. A new diagnostic method using cellulose-based devices and microfluidic chip techniques for the isolation of exosomes from aqueous humor is less cumbersome and saves time. This method will enable more investigations for aqueous humor analysis in the future.

Integration of a Genetically Encoded Calcium Molecular Sensor into Photopolymerizable Hydrogels for Micro-Optrode-Based Sensing

Genetically encoded molecular-protein sensors (GEMS) are engineered to sense and quantify a wide range of biological substances and events in cells, in vitro and even in vivo with high spatial and temporal resolution. Here, we aim to stably incorporate these proteins into a photopatternable matrix, while preserving their functionality, to extend the application of these proteins as spatially addressable optical biosensors. For this reason, we examined the fabrication of 3D hydrogel microtips doped with a genetically encoded fluorescent biosensor, GCaMP3, at the end of an optical fiber. Stable incorporation parameters of GCaMP3 into a photo-cross-linkable monomer matrix were investigated through a series of characterization and optimization experiments. Different precursor-solution formulations and irradiation parameters of in situ photopolymerization were tested to determine the factors affecting protein stability and sensor reproducibility during photoencapsulation. The microstructure and performance of hydrogel microtips were controlled by varying UV irradiation intensity as well as the molecular weight and concentration of the photocurable monomer, PEGDA (polyethylene glycol diacrylate), in precursor solution. Protein-doped hydrogel micro-optrodes (microtip sensors) were fabricated successfully and reproducibly at the distal end of optical fiber. Under optimized conditions, the bioactivity of GCaMP3 within a hydrogel matrix of micro-optrodes remained similar to that of the protein-free matrix in buffer. The limit of detection of protein optrodes for free calcium was also determined to be 4.3 nM. The hydrogel formulation and fabrication process demonstrated here using microtip optrodes can be easily adapted to other conformation-dependent protein biosensors and can be used in sensing applications.

Polypoidal Choroidal Vasculopathy

PURPOSE OF REVIEW

The goal of this paper is to review the recent literature of polypoidal choroidal vasculopathy (PCV) and provide an update on the epidemiology, pathophysiology, clinical findings, and management.

RECENT FINDINGS

Although indocyanine-green angiography (ICGA) is still the gold standard for diagnosis of PCV, the use of en face optical coherence tomography (OCT) and OCT angiography are useful tools in the diagnosis of PCV. Studies demonstrate superior treatment outcomes with combination photodynamic therapy (PDT) and anti-vascular endothelial growth factor (VEGF) therapy.

SUMMARY

PCV is a disease most commonly in Asians and African-Americans and presents with an orange-red nodule in the macula or the peripapillary region. While ICGA remains the most accurate method to diagnose PCV, newer non-invasive imaging modalities (eg. OCT-A and en face OCT) can be used to identify PCV lesions. The combination of PDT and anti-VEGF therapy is superior to either monotherapy. Future studies of OCT modalities and other anti-VEGF agents will be important in guiding PCV diagnosis and management, respectively.

Elevated angiopoietin 2 in aqueous of patients with neovascular age related macular degeneration correlates with disease severity at presentation

Angiopoietin 2 (ANG2) is a proangiogenic cytokine which may have an implication in neovascular age related macular degeneration (nAMD). In 24 eyes of 24 subjects presenting with treatment naïve nAMD and 26 eyes of 26 control patients, aqueous humor samples were collected at the time of intervention (intravitreal injection of anti-vascular endothelial growth factor or cataract extraction). Best corrected visual acuity (BCVA) with and central macular thickness (CMT) using optical coherence tomography (OCT) were measured before each injection in the nAMD group. Aqueous cytokine levels were determined by immunoassay using a multiplex array (Quansys Biosciences, Logan, UT). Levels of ANG2 in the aqueous were significantly higher in nAMD patients than those of the control group (p < 0.0001), so were hepatocyte growth factor (HGF), interleukin-8 (IL-8) and tissue inhibitor of metalloproteinase 1 (TIMP 1), all with p < 0.001. ANG2 correlated with worse BCVA (r = 0.44, p-value = 0.027) and greater CMT (r = 0.66, p-value < 0.0001) on optical coherence tomography (OCT). ANG2 is upregulated in patients with nAMD and correlates with severity of disease at presentation.