Monolithic integrated optoelectronic chip for vector force detection.

Sensors with a small footprint and real-time detection capabilities are crucial in robotic surgery and smart wearable equipment. Reducing device footprint while maintaining its high performance is a major challenge and a significant limitation to their development. Here, we proposed a monolithic integrated micro-scale sensor, which can be used for vector force detection. This sensor combines an optical source, four photodetectors, and a hemispherical silicone elastomer component on the same sapphire-based AlGaInP wafer. The chip-scale optical coupling is achieved by employing the laser lift-off techniques and the flip-chip bonding to a processed sapphire substrate. This hemispherical structure device can detect normal and shear forces as low as 1 mN within a measurement range of 0-220 mN for normal force and 0-15 mN for shear force. After packaging, the sensor is capable of detecting forces over a broader range, with measurement capabilities extending up to 10 N for normal forces and 0.2 N for shear forces. It has an accuracy of detecting a minimum normal force of 25 mN and a minimum shear force of 20 mN. Furthermore, this sensor has been validated to have a compact footprint of approximately 1.5 mm2, while maintaining high real-time response. We also demonstrate its promising potential by combining this sensor with fine surface texture perception in the fields of compact medical robot interaction and wearable devices.

Associations of CSF BACE1 with amyloid pathology, neurodegeneration, and cognition in Alzheimer's disease.

Β-site amyloid precursor protein (APP) cleaving enzyme (BACE1) is a crucial protease in the production of amyloid-ß (Aß) in Alzheimer's disease (AD) patients. However, the side effects observed in clinical trials of BACE1 inhibitors, including reduction in brain volume and cognitive worsening, suggest that the exact role of BACE1 in AD pathology is not fully understood. To further investigate this, we examined cerebrospinal fluid (CSF) levels of BACE1 and its cleaved product sAPPß that reflects BACE1 activity in the China Aging and Neurodegenerative Disorder Initiative cohort. We found significant correlations between CSF BACE1 or sAPPß levels and CSF Aß40, Aß42, and Aß42/Aß40 ratio, but not with amyloid deposition detected by 18F-Florbetapir PET. Additionally, CSF BACE1 and sAPPß levels were positively associated with cortical thickness in multiple brain regions, and higher levels of sAPPß were linked to increased cortical glucose metabolism in frontal and supramarginal areas. Interestingly, individuals with higher baseline levels of CSF BACE1 exhibited slower rates of brain volume reduction and cognitive worsening over time. This suggests that increased levels and activity of BACE1 may not be the determining factor for amyloid deposition, but instead, may be associated with increased neuronal activity and potentially providing protection against neurodegeneration in AD.

The relationship between potassium levels and 28-day mortality in sepsis patients: Secondary data analysis using the MIMIC-IV database.

Objective: The goal of the research is to investigate the link between serum potassium levels and death after 28 days in sepsis patients, utilizing an extensive sample of patients from the multi-center Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Current research on serum potassium levels and 28-day mortality in sepsis patients is questionable. This study adds to the growing body of evidence linking serum potassium levels to the 28-day possibility of death in patients with sepsis. Methods: We collected 349,08 patients with sepsis from the retrospective cohort MIMIC-IV database, using serum potassium level on the first day of admission to the intensive care unit as the exposure variable and mortality at 28 days as the outcome variable. And controlled for confounding characteristics including gender, age, ethnicity, and vital signs during admission. Results: Serum potassium has a U-shaped connection with 28-day mortality in patients suffering from sepsis. The turning point was 4.10 mmol/L (95 % confidence interval: 4.03 to 4.22). Serum potassium and 28-day mortality were negatively linked on the inflection point's left side (OR: 0.72; 95 % CI: 0.63 to 0.83, P < 0.0001); on the opposing side of the point of inflexion, serum potassium was enthusiastically attached to 28-day mortality. (OR: 1.13; 95 % CI: 1.06 to 1.21, P < 0.0001). Conclusion: The research conducted found that too high or too low potassium levels were linked to a 28-day risk of mortality in humans with sepsis.

Knowledge, attitudes, and practices (KAPs) regarding tick-borne rickettsial disease among medical staff in endemic areas of China.

Tick-borne rickettsial disease (TBRD) is a perilous acute infection that often eludes diagnosis in its early stages. The triad of knowledge, attitudes, and practices (KAPs) among medical professionals is key to reducing missed diagnosis rates. Therefore, a meticulous evaluation of KAPs is imperative. This study aimed to delve into the understanding of TBRD and explore the beliefs and practices related to personal prevention methods among individuals in Lu'an, a hotspot for TBRD. During the summer months of 2023, convenience sampling was employed by circulating a confidential questionnaire to 1,206 participants in the endemic regions of China. This questionnaire painted a comprehensive picture of the participants' sociodemographic profiles and their KAPs levels vis-à-vis TBRD. The findings revealed that participants scored a mere 55.78% in knowledge, while their attitudes and practices garnered impressive scores of 90.09% and 90.83%, respectively. Upon further analysis using multiple linear regression, several intriguing patterns emerged. Male participants, employed in the Infectious Disease Department, held vice-senior or higher titles, or had prior medical training demonstrated superior knowledge scores. On the other hand, medical personnel who were younger than 30, possessed graduate degrees or higher qualifications, and had training excelled in attitudes and practices. Notably, when employing the Boston Consulting Group (BCG) matrix, a significant distribution of medical personnel was observed across the four quadrants. Specifically, 37.43%, 13.19%, 19.61%, and 29.77% fell into the first, second, third, and fourth quadrants. This survey underscores the commendable attitudes and practices of medical staff towards TBRD in endemic regions of China. However, their knowledge level remains wanting and demands urgent improvement.

Impact of Phosphorylation at Various Sites on the Active Pocket of Human Ferrochelatase: Insights from Molecular Dynamics Simulations.

Ferrochelatase (FECH) is the terminal enzyme in human heme biosynthesis, catalyzing the insertion of ferrous iron into protoporphyrin IX (PPIX) to form protoheme IX (Heme). Phosphorylation increases the activity of FECH, and it has been confirmed that the activity of FECH phosphorylated at T116 increases. However, it remains unclear whether the T116 site and other potential phosphorylation modification sites collaboratively regulate the activity of FECH. In this study, we identified a new phosphorylation site, T218, and explored the allosteric effects of unphosphorylated (UP), PT116, PT218, and PT116 + PT218 states on FECH in the presence and absence of substrates (PPIX and Heme) using molecular dynamics (MD) simulations. Binding free energies were evaluated with the MM/PBSA method. Our findings indicate that the PT116 + PT218 state exhibits the lowest binding free energy with PPIX, suggesting the strongest binding affinity. Additionally, this state showed a higher binding free energy with Heme compared to UP, which facilitates Heme release. Moreover, employing multiple analysis methods, including free energy landscape (FEL), principal component analysis (PCA), dynamic cross-correlation matrix (DCCM), and hydrogen bond interaction analysis, we demonstrated that phosphorylation significantly affects the dynamic behavior and binding patterns of substrates to FECH. Insights from this study provide valuable theoretical guidance for treating conditions related to disrupted heme metabolism, such as various porphyrias and iron-related disorders.

Efficacy and Safety of High-Viscosity Bone Cement in Percutaneous Vertebroplasty for Kummell's Disease.

Background: To analyze and evaluate the clinical outcomes of using high-viscosity bone cement compared to low-viscosity bone cement in percutaneous vertebroplasty (PVP) for treatment of Kummell's disease. Methods: From July 2017 to July 2019, 68 Kummell's disease patients who underwent PVP were chosen and separated into 2 groups: H group (n = 34), were treated with high-viscosity bone cement and L group (n = 34), treated with low-viscosity bone cement during treatment. The operation time, number of fluoroscopy tests done, and amount of bone cement perfusion were recorded for both groups. Clinical outcomes were compared, by measuring their Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Kyphosis Cobb's angle, vertebral height compression rate, and other complications. Results: High-viscosity group showed less operation time and reduced number of fluoroscopy tests than the low-viscosity group (P < 0.05). When compared to preoperative period, both groups' VAS and ODI scores were significantly reduced at 1 day and 1 year postoperatively (P < 0.05). The vertebral height compression rate and Cobb's angle were significantly lower (P < 0.05) in both groups after surgery compared with those before surgery (P < 0.05). The cement leakage rate in group H was 26.5%, which was significantly lower than that in group L, which was 61.8% (P < 0.05). Conclusions: High-viscosity and low-viscosity bone cement in PVP have similar clinical efficacy in reducing pain in patients during the treatment, but in contrast, high-viscosity bone cement shortens the operative time, reduces number of fluoroscopy views and vertebral cement leakage and improves surgical safety.

A fluorescent terbium-metal-organic framework material for high-sensitivity detection of vomitoxin and oxytetracycline hydrochloride in water.

A unique luminescent lanthanide metal-organic framework (LnMOF)-based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC-HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M-1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb-MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern-Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC-HCL with a detection limit of 0.039 µM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC-HCL in water.

Non-equilibrium compression achieving high sensitivity and linearity for iontronic pressure sensors.

Flexible pressure sensors with high sensitivity and linearity are highly desirable for robot sensing and human physiological signal detection. However, the current strategies for stabilizing axial microstructures (e.g., micro-pyramids) are mainly susceptible to structural stiffening during compression, thereby limiting the realization of high sensitivity and linearity. Here, we report a bending-induced non-equilibrium compression process that effectively enhances the compressibility of microstructures, thereby crucially improving the efficiency of interfacial area growth of electric double layer (EDL). Based on this principle, we fabricate an iontronic flexible pressure sensor with vertical graphene (VG) array electrodes. Ultra-high sensitivity (185.09 kPa-1) and linearity (R2 = 0.9999) are realized over a wide pressure range (0.49 Pa-66.67 kPa). It also exhibits remarkable mechanical stability during compression and bending. The sensor is successfully employed in a robotic gripping task to recognize the targets of different materials and shapes based on a multilayer perception (MLP) neural network. It opens the door to realizing haptic sensing capabilities for robotic hands and prosthetic limbs.

Aging-induced tRNAGlu-derived fragment impairs glutamate biosynthesis by targeting mitochondrial translation-dependent cristae organization.

Mitochondrial cristae, infoldings of the mitochondrial inner membrane, undergo aberrant changes in their architecture with age. However, the underlying molecular mechanisms and their contribution to brain aging are largely elusive. Here, we observe an age-dependent accumulation of Glu-5'tsRNA-CTC, a transfer-RNA-derived small RNA (tsRNA), derived from nuclear-encoded tRNAGlu in the mitochondria of glutaminergic neurons. Mitochondrial Glu-5'tsRNA-CTC disrupts the binding of mt-tRNALeu and leucyl-tRNA synthetase2 (LaRs2), impairing mt-tRNALeu aminoacylation and mitochondria-encoded protein translation. Mitochondrial translation defects disrupt cristae organization, leading to damaged glutaminase (GLS)-dependent glutamate formation and reduced synaptosomal glutamate levels. Moreover, reduction of Glu-5'tsRNA-CTC protects aged brains from age-related defects in mitochondrial cristae organization, glutamate metabolism, synaptic structures, and memory. Thus, beyond illustrating a physiological role for normal mitochondrial cristae ultrastructure in maintaining glutamate levels, our study defines a pathological role for tsRNAs in brain aging and age-related memory decline.

Germline RECQL gene mutations in Chinese patients with breast cancer.

Introduction: Breast cancer is the most common malignant tumor in women, seriously threatening health and survival. TP-dependent DNA helicase Q1 (RECQL) is a breast cancer susceptibility gene with possible familial links. However, RECQL gene mutations among Chinese women with breast cancer have not been evaluated. Therefore, this study assessed RECQL mutations and their relationships with clinicopathological and epidemiological characteristics in Chinese women with breast cancer. Method: Clinical information was also obtained via the hospital information system and a follow-up questionnaire. Peripheral venous blood (2 mL) was extracted from all patients and stored at -80°C for future use; the early venous blood samples were from our hospital's sample bank. RECQL gene sequencing were performed by the Shanghai Aishe Gene Company (China). Results: We found that a RECQL mutation is a susceptibility factor for breast cancer. Moreover, patients with RECQL mutations were more likely to have a family history of breast cancer than those without. Also, patients with RECQL variants of uncertain significance (VUS) were less likely to develop invasive ductal carcinoma than those without. In addition, unexplained RECQL mutations occurred more often in patients with human epidermal growth factor receptor 2+ breast cancer than in those with other subtypes. Discussion: These results provide a basis for creating screening criteria specific to Chinese women. However, the frequency of RECQL mutations was low, and the number of pathogenic mutations was too small and could not be analyzed. Thus, more extensive, long-term studies that include other functional experiments are needed to verify these results.

Giant vesicles form in physiological saline and encapsulate pDNA by the modified electroformation method.

Giant vesicles (GVs) are used to study the structures and functions of cells and cell membranes. Electroformation is the most commonly used method for GV preparation. However, the electroformation of GVs is hindered in highly concentrated ionic solutions, limiting their application as cell models for research under physiological conditions. In this study, giant multilayer vesicles were successfully generated in physiological saline using a modified electroformation device by adding an insulating layer between the two electrode plates. The influence of the electric frequency and strength on the electroformation of GVs in physiological saline was explored, and a possible mechanism for this improvement was assessed. It has been shown that an insulating layer between the two electrodes can improve the electroformation of GVs in physiological saline by increasing the electrical impedance, which is weakened by the saline solution, thereby restoring the reduced effective electric field strength. Furthermore, macromolecular plasmid DNA (pDNA) was successfully encapsulated in the electroformed GVs of the modified device. This modified electroformation method may be useful for generating eukaryotic cell models under physiological conditions.

Characteristics of Spinal Morphology According to the Global Alignment and Proportion (GAP) Score in a Diverse, Asymptomatic Cohort: Multi-Ethnic Alignment Normative Study.

STUDY DESIGN: Multi-Ethnic Alignment Normative Study (MEANS) cohort: prospective, cross-sectional, multicenter. OBJECTIVE: To analyze the distribution of GAP scores in the MEANS cohort and compare the spinal shape via stratification by GAP alignment category, age, and country. SUMMARY OF BACKGROUND DATA: The GAP score has been used to categorize spinal morphology and prognosticate adult spinal deformity surgical outcomes and mechanical complications. We analyzed a large, multiethnic, asymptomatic cohort to assess the distribution of GAP scores. METHODS: Four hundred sixty-seven healthy volunteers without spinal disorders were recruited in five countries. Sagittal radiographic parameters were measured via the EOS imaging system. The GAP total and constituent factor scores were calculated for each patient. Kruskal-Wallis rank sum test was performed to compare variables across groups, followed by the post hoc Games-Howell test. Fisher exact test was used to compare categorical variables. The significance level was set to P <0.05. RESULTS: In the MEANS cohort, 13.7% (64/467) of volunteers were ≥60 years old, and 86.3% (403/467) were <60 years old. 76.9% (359/467) was proportioned, 19.5% (91/467) was moderately disproportioned, and 3.6% (17/467) was severely disproportioned. There was no significant difference in the frequency of proportioned, moderately, or severely disproportioned GAP between subjects from different countries ( P =0.060). Those with severely disproportioned GAP alignment were on average 14.5 years older ( P =0.016), had 23.1° lower magnitude lumbar lordosis (LL) ( P <0.001), 14.2° higher pelvic tilt ( P <0.001), 13.3° lower sacral slope ( P <0.001), and 24.1° higher pelvic-incidence (PI)-LL mismatch ( P <0.001), 18.2° higher global tilt ( P <0.001) than those with proportioned GAP; thoracic kyphosis and PI were not significantly different ( P >0.05). CONCLUSIONS: The GAP system applies to a large, multiethnic, asymptomatic cohort. Spinal alignment should be considered on a spectrum, as 19.5% of the asymptomatic volunteers were classified as moderately disproportioned and 3.6% severely disproportioned. Radiographic malalignment does not always indicate symptoms or pathology. LEVEL OF EVIDENCE: 3.

Toxicity Assessment of Environmental Liquid Crystal Monomers: A Bacteriological Investigation on Escherichia coli and Staphylococcus epidermidis.

The widespread existence of liquid crystal monomers (LCMs) in various environmental matrices has been demonstrated, yet studies on the toxicological effects of LCMs are considerably scarce and are urgently needed to be conducted to assess the adverse impacts on ecology and human health. Here, we conducted a bacteriological study on two representative human commensal bacteria, Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis), to investigate the effect of LCMs at human-relevant dosage and maximum environmental concentration on growth, metabolome, enzymatic activity, and mRNA expression. Microbial growth results exhibited that the highest inhibition ratio of LCMs on S. epidermidis reached 33.6% in our set concentration range, while the corresponding data on E. coli was only 14.3%. Additionally, LCMs showed more dose-dependent toxicity to S. epidermidis rather than E. coli. A novel in vivo solid-phase microextraction (SPME) fiber was applied to capture the in vivo metabolites of microorganisms. In vivo metabolomic analyses revealed that dysregulated fatty acid metabolism-related products of both bacteria accounted for >50% of the total number of differential substances, and the results also showed the species-specific and concentration-dependent metabolic dysregulation in LCM-exposed bacteria. The determination of enzymatic activity and mRNA relative expression levels related to oxidative stress confirmed our speculation that the adverse effects were related to the oxidative metabolism of fatty acids. This study complements the gaps in toxicity data for LCMs against bacteria and provides a new and important insight regarding metabolic dysregulation induced by environmental LCMs in human commensal bacteria.

The first dorsal metacarpal artery flaps versus reverse homodigital dorsal flaps for thumb reconstruction: a systematic review and meta-analysis.

PURPOSE: This review was performed to systematically compare the effectiveness and safety of the first dorsal metacarpal artery flaps (FDMAF) and reverse homodigital dorsal flaps (RHDF) for thumb reconstruction. METHODS: All literatures, which compared FDMAF versus RHDF for thumb reconstruction, were acquired through a comprehensive search in multiple databases from inception until 31st August 2022. A meta-analysis was performed using the Cochrane Collaboration's RevMan 5.4 software. RESULTS: A total of 19 articles were retrieved, comprising 396 patients in the FDMAF group and 423 patients in the RHDF group. The pooled estimates suggested that there were no significant differences in venous congestion, complications about flap necrosis and reduced range of motion (ROM) of thumb, static 2-point discrimination (S-2PD) between the two groups. On the other hand, patients in the RHDF group had less vascular crisis (odds ratio [OR] = 3.15, 95%CI, 1.31-7.56), complications about poor cortical reorientation (OR = 440.02, 95%CI, 91.97-2105.27) and higher satisfaction rate (OR = 0.56, 95% CI, 0.33-0.96) than those in the FDMAF group. CONCLUSIONS: The two surgical procedures were both safe and reliable since no significant differences were found in flap necrosis between the two groups. However, the patients in the RHDF group had less complications about vascular crisis, poor cortical reorientation and higher satisfaction rate. Accordingly, we thought RHDF may be more superior for thumb reconstruction than FDMAF.

Characteristics of Spinal Morphology According to the "Current" and "Theoretical" Roussouly Classification Systems in a Diverse, Asymptomatic Cohort: Multi-Ethnic Alignment Normative Study (MEANS).

STUDY DESIGN: Cross-sectional cohort study. OBJECTIVE: To classify spinal morphology using the "current" and "theoretical" Roussouly systems and assess sagittal alignment in an asymptomatic cohort. METHODS: 467 asymptomatic volunteers were recruited from 5 countries. Radiographic parameters were measured via the EOS imaging system. "Current" and "theoretical" Roussouly classification was assigned with sagittal whole spine imaging using sacral slope (SS), pelvic incidence (PI), and the lumbar apex. One-way analysis of variance (ANOVA) was performed to compare subject characteristics across Roussouly types, followed by post hoc Bonferroni correction. RESULTS: Volunteers were categorized into 4 groups (Types 1-4) and 1 subgroup (Type 3 AP) using the "current" and "theoretical" Roussouly systems. The mean PI in "current" Roussouly groups was 40.8° (Type 1), 43.6° (Type 2), 52.4° (Type 3), 62.4° (Type 4), and 43.7° (Type 3AP). The mean PI in "theoretical" Roussouly groups was 36.5° (Type 1), 39.1°(Type 2), 52.5° (Type 3), 67.3° (Type 4), and 51.0° (Type 3AP). The difference in PI between "current" and "theoretical" Roussouly types was significant for Type 1 (P = .02), Type 2 (P < .001), Type 4 (P < .001), and Type 3AP (P < .001). 34.7% of subjects had a "current" Roussouly type different from the "theoretical" type. Type 3 theoretical shape had the most frequent mismatch, constituting 61.1% of the mismatched subjects. 51.5% of mismatched Type 3 become "current" Type 4. CONCLUSION: The distribution of Roussouly types differs depending on whether the "current" or "theoretical" classification are employed. A sizeable proportion of volunteers exhibited current and theoretical type mismatch, highlighting the need to interpret sagittal alignment cautiously when utilizing the Roussouly system.

Arthroscopic wafer procedure versus ulnar shortening osteotomy for ulnar impaction syndrome: a systematic review and meta-analysis.

PURPOSE: This study aimed to systematically compare the efficacy and safety of arthroscopic wafer procedure (AWP) versus ulnar shortening osteotomy (USO) for ulnar impaction syndrome (UIS) treatment. METHODS: All the studies included in this meta-analysis compared the efficacy of AWP to USO for UIS and were acquired through a comprehensive search across multiple databases. The meta-analysis was performed by calculating the effect sizes with the Cochrane Collaboration's RevMan 5.4 software. RESULTS: A total of 8 articles were included in this analysis, comprising 148 cases in the AWP group and 163 cases in the USO group. The pooled estimates indicated no significant differences in combined Darrow's Criteria or Modified Mayo Wrist Score, Modified Mayo Wrist Score, DASH scores, grip strength, VAS score, and postoperative ulnar variation. On the other hand, the patients in the AWP group exhibited fewer complications (OR = 0.17, 95%CI 0.05-0.54, P = 0.003) and a lower reoperation rate (OR = 0.12, 95%CI 0.05-0.28, P < 0.00001) than those in the USO group. CONCLUSIONS: The two surgical techniques were both effective in treating UIS but the AWP group showed fewer complications and a lower reoperation rate. Therefore, AWP may present a superior alternative for UIS treatment.

Bipoladien A, a Sesterterpenoid Containing an Undescribed 5/8/5/7 Carbon Skeleton from Bipolaris maydis.

Bipoladiens A-E (1-5), five new ophiobolin-derived sesterterpenoids, and a known compound 6 (bipolaricin R) were isolated from the cultures of the phytopathogenic fungus Bipolaris maydis. Their structures and absolute configurations were elucidated based on comprehensive spectroscopic analyses, HRESIMS, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction analyses. Notably, compound 1 has an undescribed tetracyclic 5/8/5/7 fused carbon skeleton, and compound 2 possesses a rare multicyclic caged ring system. The biosynthetic pathway of 1 was proposed starting from 6 via a series of oxidation and cyclization reactions. Compound 6 showed excellent antiproliferation and apoptosis induction effects against A549 cell line. Additionally, compounds 5 and 6 exhibited noticeable antimicrobial ability against Bacillus cereus, Staphylococcus aureus, and Staphylococcus epidermidis. These findings not only developed the chemical and bioactivities diversities of ophiobolin-sesterterpenoid but also provided an idea to boost the application of natural products in the control of food pathogens.

Cation-π Interactions Greatly Influence Ion Transportability of the Light-Driven Sodium Pump KR2: A Molecular Dynamics Study.

Krokinobacter eikastus rhodopsin 2 (KR2) is a typical light-driven sodium pump. Although wild-type KR2 exhibits high Na+ selectivity, mutagenesis performed on the residues constituting the entrance enables permeation of K+ and Cs+, while the underlying mechanism remains elusive. This study presents a comprehensive molecular dynamics investigation, including force field optimization, metadynamics, and alchemical free energy methods, to explore the N61L/G263F mutant of KR2, which exhibits transportability for K+ and Cs+. The introduced Phe263 residue can directly promote ion binding at the entrance through cation-π interactions, while the N61L mutation can enhance ion binding at Phe46 by relieving steric hindrance. These results suggest that cation-π interactions may significantly influence the ion transportability and selectivity of KR2, which can provide important insights for protein engineering and the design of artificial ion transporters.