Direct response of liquid crystal to pH changes for wide range pH sensing via the whispering gallery mode.

pH sensing is essential in various fields including healthcare, environmental monitoring, food safety, and agriculture. In this Letter, we propose a method for a wide-range pH measurement based on the direct response of liquid crystal (LC) to pH variations via the whispering gallery mode (WGM). The liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) is selected for its excellent optoelectronic properties and the birefringence of 5CB microdroplets serving as spherical resonators. This sensor achieves wide-range pH sensing without any intermediaries. Polarized optical microscopy (POM) and WGM provide a qualitative morphological analysis and accurate quantitative spectral measurements. Under alkaline conditions (pH 7.6 to 13.3), POM images of 5CB microdroplets show a complete transition from bipolar to radial structures, with an average sensitivity of 1.78 nm/pH of redshift in WGM spectra. In acidic conditions (pH 6.65 to 1.5), structural changes observed by POM are minor, with a sensitivity of 1.06 nm/pH of blueshift in WGM spectra. This difference is attributed to the varying refractive indices of HCl and NaOH solutions. This method offers a reference for theoretical studies on pH and LC interactions and holds promise for the development of LC-based pH sensors.

A Molecular Switch-Integrated Nanoplatform Enables Photo-Unlocked Antibacterial Drug Delivery for Synergistic Abscess Therapy.

Drug delivery systems (DDSs) capable of sequential multistage drug release are urgently needed for antibacterial applications. Herein, a molecular switch-integrated, photo-responsive nanoplatform is reported based on hollow mesoporous silica nanospheres (HMSN) loaded with silver nanoparticles (Ag NPs), vancomycin (Van), and hemin (HAVH) for bacteria elimination and abscess therapy. Upon near-infrared (NIR) light irradiation, the molecular switch, hemin, can effuse from the mesopores of HMSN, triggering the release of pre-loaded Ag+ and Van, which enables photothermal-modulated drug release and synergistic photothermal-chemo therapy (PTT-CHT). The HAVH_NIR irreversibly disrupts the bacterial cell membrane, facilitating the penetration of Ag+ and Van. It is found that these compounds restrain the transcription and translation of ribosomes and lead to rapid bacterial death. Furthermore, hemin can effectively inhibit excessive inflammatory responses associated with the treatment, promoting accelerated wound healing in a murine abscess model. This work presents a new strategy for antibacterial drug delivery with high controllability and extendibility, which may benefit the development of smart multifunctional nanomedicine for diseases not limited to bacterial infections.

Antimicrobial Zeolitic Imidazolate Frameworks with Dual Mechanisms of Action.

The horizontal transfer of drug-resistant genes and the formation of biofilm barriers have threatened the therapeutic efficacy of conventional antibiotic drugs. Development of non-antibiotic agents with high delivery efficiency through bacterial biofilms is urgently required. A pyrithione (PT)-loading zeolitic imidazolate framework (ZIF-8@PT) is synthesized to destroy biofilms and improve the sensitivity of bacteria to PT. ZIF-8@PT can target and destroy the biofilm as well as the cell membrane, promoting the intracellular delivery of PT and possibly its interaction with SmpB, a protein that could regulate the drug resistance of bacteria. ZIF-8@PT effectively suppresses abdominal infections induced by multiresistant Aeromonas veronii C4 in rodent models without systemic toxicity. ZIF-8@PT promises wide applications in treating infections caused by multidrug-resistant bacteria through a dual mechanism of action.

Compact fiber sensor for pH measurement based on the composite effect of hydrogel deformation and LC refractive index variation.

A novel, to the best of our knowledge, type of compact pH fiber sensor combined with a hydrogel based on the whispering gallery mode (WGM) is proposed and integrates a liquid crystal (LC) microdroplet in a capillary in a compact structure as small as 180 µm. In the research, the hydrogel performs both as a supporting frame and a responsive material that causes morphological deformation of the LC microdroplet with pH variation. Moreover, a new phenomenon of pH-induced LC refractive index variation is observed and applied in the pH measurement, so that the acid itself can also lead the LC microdroplet structure transition. Thus, the WGM method is applied to detect the composite effect simultaneously to improve the sensing capability. The sensitivity of the sensor in the pH range from 4.55 to 6.86 reaches 3.19 nm/pH. The response time is short, within 60 s. The simple and compact structure of the sensor reduces the cost and enhances the stability, which is of great potential for biomedical pH measurement.

Super-compact shearography based on a single diffractive optical element with 3-in-1 phase mask.

This Letter communicates a new, to the best of our knowledge, designing framework of shearography. The three elementary functional parts of quantitative shearography, namely imaging, shearing, and phase shifting, are integrated into a single diffractive optical element (DOE), named a 3-in-1 phase mask. The idea breaks through the conventional designing routine of shearography, and converts it from the combination of individual optical elements to the spatial manipulation of phase. The slicing, splicing, and alternating strategy is proposed to generate the 3-in-1 phase mask from a given number of sequenced Fresnel lenses and a modified echelle grating. The operating component is merely a DOE, which renders the optics naturally coaxial. The delivered shearography system enjoys a super-compact configuration, a high level of robustness and stability, and the potential for implementing outside optics laboratories. Crucial system parameters, e.g., shear amount, shear direction, working distance, can be readily shifted on call by re-making the 3-in-1 phase mask. The future of the present idea is in its shape and seems promising with lithography, micromachining, and metasurfaces.

Ultra-low sample consumption consecutive-detection method for biochemical molecules based on a whispering gallery mode with a liquid crystal microdroplet.

Ultra-low sample consumption detection has many applications in molecular biology, bioanalytical chemistry, and medical science. In this Letter, a novel, to the best of our knowledge, simple type of ultra-low sample consumption detection method based on a whispering gallery mode is proposed as a means to realize consecutive detection with a liquid crystal (LC) microdroplet for biochemical molecule detection, using deoxyribonucleic acid (DNA) as a model biomarker. The sensor consists of a 105-µm-core multimode fiber fused with a hollow capillary tube, with the LC microdroplet suspended stably in the testing solution. Its application to the detection of salmon sperm DNA yielded an adjustable measurement range of 3.75-11.25 µg/ml and a sensitivity of 0.33 nm/µg/ml. The test solution required as little as 3 nl of the sample, and the limit of detection was 1.32 µg/ml, which corresponds to the effective detection of as little as 3.96 pg of DNA. This method has great potential for application in the ultra-low sample consumption detection of biochemical molecules.

All fiber compact bending sensor with high sensitivity based on a multimode fiber embedded chirped long-period grating.

We investigated and prepared a chirped long-period grating for high sensitivity bending measurement. The novel fiber structure is composed of the multimode fiber (MMF) with fixed length and gradually longer single-mode fiber using the continuous splicing method. The powerful ability of refractive index modulation in the MMF renders the miniaturization of the sensor. The total length of the sensor is 3.45 mm. Chirped period arrangement is adopted to improve the bending sensitivity. Through numerical calculation, the chirp coefficient is determined, and the clear resonance peaks are obtained using the wavelength scanning. The experimental results of several samples show that the maximum bending sensitivity is 53.68nm/m-1 at 0-1.803m-1. With the advantages of small size and high sensitivity, the sensor is especially suitable for bending sensing with a micro-structure.

The ethics and politics of patient-physician mistrust in contemporary China.

Focusing on the shared sense of victimization and disadvantage-ness by both patients and doctors/medical workers in cases of medical conflicts, this paper aims to examine the current patient-doctor tensions in the larger context of moral transformation in Chinese society since the 1980s. Although the decline of public trust in certain aspects is closely associated with the impact of commodification and commercialization of medical sector during the past two decades, other factors play important role as well. In the case of patient-doctor tension, mutual disrespect and mistrust also result from the ongoing process of individualization and the remaking of moral self, in which the individual demand for respect, dignity, and trust seem to have unexpectedly and ironically contributed to the rise of tensions and conflicts between patients and doctors as well as other medical workers.

The Chinese path to individualization.

This article explores the rise of the individual and the consequential individualization of society which should be viewed as a reflexive part of China's state-sponsored quest for modernity. It traces the origin of the individualization process to the Maoist era, arguing that some collectivist programmes of social engineering and the socialist path of modernization under Maoism ironically resulted in a partial individualization of Chinese society. Examining profound social changes during the three decades of the post-Mao reforms, the article reveals a number of similarities with the individualization process in Western Europe but also demonstrates some important differences. In the last section, the theoretical implications of the Chinese case in light of Ulrich Beck's theory of individualization and second modernity are discussed.