Tamper-Proof Time-Temperature Indicator for Inspecting Ultracold Supply Chain

Hydrogen Bond-Mediated Self-Shielded Moisture-Responsive Structural Color for Time-Temperature Indicating

Effective monitoring of the time-temperature history of biological reagents, chemical drugs, and perishable foods during cold chain storage is crucial for ensuring their quality and efficacy. Time-temperature indicators (TTIs) are developed to assess the cumulative impact of time and temperature on product quality. However, current indicators face challenges related to complex wrapping procedures, narrow tracking ranges, susceptibility to photobleaching, and pre-use instability, hampering widespread use. Herein, the first moisture-responsive 1D photonic crystal (1DPC) TTIs featuring robust structural colors, customizable time-temperature ranges, and reliable renewability are demonstrated. The indicators exhibit distinct color-changing responsiveness toward water vapor, which remains observable after prolonged storage at low temperatures. Significantly, the moisture responsiveness gradually diminishes at elevated temperatures over time due to ambient water-induced hydrogen bond formation, effectively shielding the indicator from external stimuli. This property enables the naked-eye inspection of product efficacy during cold chain storage. Additionally, the endowed flexibility of the TTI facilitates its easy attachment to targets, functioning as a convenient indicator label. Remarkably, the indicator can be stably stored for an extended period at room temperature before use, thereby showcasing substantial market potential.

Design and Characterization of a New Formulation for the Delivery of COVID-19-mRNA Vaccine to the Nasal Mucosa

Chitosan, a natural polysaccharide derived from chitin, possesses biocompatibility, biodegradability, and mucoadhesive characteristics, making it an attractive material for the delivery of mRNA payloads to the nasal mucosa and promoting their uptake by target cells such as epithelial and immune cells (e.g., dendritic cells and macrophages). In this project, we aimed at developing novel lipid-based nanoformulations for mRNA delivery to counteract the pandemic caused by SARS-CoV-2 virus. The formulations achieved a mRNA encapsulation efficiency of ~80.2% with chitosan-lipid nanoparticles, as measured by the RiboGreen assay. Furthermore, the evaluation of SARS-CoV-2 Spike (S) receptor-binding domain (RBD) expression via ELISA for our vaccine formulations showed transfection levels in human embryonic kidney cells (HEK 293), lung carcinoma cells (A549), and dendritic cells (DC 2.4) equal to 9.9 ± 0.1 ng/mL (174.7 ± 1.1 fold change from untreated cells (UT)), 7.0 ± 0.2 ng/mL (128.1 ± 4.9 fold change from UT), and 0.9 ± 0.0 ng/mL (18.0 ± 0.1 fold change from UT), respectively. Our most promising vaccine formulation was also demonstrated to be amenable to lyophilization with minimal degradation of loaded mRNA, paving the way towards a more accessible and stable vaccine. Preliminary in vivo studies in mice were performed to assess the systemic and local immune responses. Nasal bronchoalveolar lavage fluid (BALF) wash showed that utilizing the optimized formulation resulted in local antibody concentrations and did not trigger any systemic antibody response. However, if further improved and developed, it could potentially contribute to the management of COVID-19 through nasopharyngeal immunization strategies.

Practical Applications of Self-Healing Polymers Beyond Mechanical and Electrical Recovery

Self-healing polymeric materials, which can repair physical damage, offer promising prospects for protective applications across various industries. Although prolonged durability and resource conservation are key advantages, focusing solely on mechanical recovery may limit the market potential of these materials. The unique physical properties of self-healing polymers, such as interfacial reduction, seamless connection lines, temperature/pressure responses, and phase transitions, enable a multitude of innovative applications. In this perspective, the diverse applications of self-healing polymers beyond their traditional mechanical strength are emphasized and their potential in various sectors such as food packaging, damage-reporting, radiation shielding, acoustic conservation, biomedical monitoring, and tissue regeneration is explored. With regards to the commercialization challenges, including scalability, robustness, and performance degradation under extreme conditions, strategies to overcome these limitations and promote successful industrialization are discussed. Furthermore, the potential impacts of self-healing materials on future research directions, encompassing environmental sustainability, advanced computational techniques, integration with emerging technologies, and tailoring materials for specific applications are examined. This perspective aims to inspire interdisciplinary approaches and foster the adoption of self-healing materials in various real-life settings, ultimately contributing to the development of next-generation materials.

Recording Temperature with Magnetic Supraparticles

Small-sized temperature indicator additives autonomously record temperature events via a gradual irreversible signal change. This permits, for instance, the indication of possible cold-chain breaches or failure of electronics but also curing of glues. Thus, information about the materials' thermal history can be obtained upon signal detection at every point of interest. In this work, maximum-temperature indicators with magnetic readout based on micrometer-sized supraparticles (SPs) are introduced. The magnetic signal transduction is, by nature, independent of the materials' optical properties. This facilitates the determination of valuable temperature information from the inside, that is, the bulk, even of dark and opaque macroscopic objects, which might differ from their surface. Compared to state-of-the-art optical temperature indicators, complementary magnetic readout characteristics ultimately expand their applicability. The conceptualized SPs are hierarchically structured assemblies of environmentally friendly, inexpensive iron oxide nanoparticles and thermoplastic polymer. Irreversible structural changes, induced by polymer softening, yield magnetic interaction changes within and between the hierarchic sub-structures, which are distinguishable and define the temperature indication mechanism. The fundamental understanding of the SPs' working principle enables customization of the particles' working range, response time, and sensitivity, using a toolbox-like manufacturing approach. The magnetic signal change is detected self-referenced, fast, and contactless.

Nanostructured Temperature Indicator for Cold Chain Logistics

Food, chemicals, agricultural products, drugs, and vaccines should be transported and stored within an appropriate low-temperature range, following cold chain logistics. Violations of the required temperature regime are generally reported by time-temperature indicators; however, current sensors do not cover a sufficiently broad low-temperature range and may lack thermal and photostability. Here, we report a nanostructured solvatochromic temperature indicator formed from cellulose nanocrystals decorated with carbon dots (C-dots). The indicator utilizes a strong nonlinear dependence of photoluminescence of C-dots on the composition of water/dimethyl sulfoxide (DMSO) solvent and a composition-dependent variation of the melting temperature of the water/DMSO mixture. Exceeding the temperature of the frozen mixed solvent above a designated threshold value results in solvent melting, flow, and impregnation of the nanostructured film, thus causing an irreversible change in the intensity and wavelength of photoluminescence emission of the film, which is reported both qualitatively and quantitatively. The indicator covers a temperature range from -68 to +19 °C and is cost-efficient, portable and photo- and thermostable.

Oh D. Determination of Methanol in Commercialized Alcohol-based Hand Sanitizing and Other Similar Products using Headspace GC-MS

Background:

Demand for alcohol-based products, including gel- and aqueous-type hand sanitizers, room sprays, and mouthwashes, has sharply increased during the ongoing COVID-19 pandemic because of their microbicidal properties. However, toxic methanol can be found from intentional addition of methanol by manufacturers and invariable production during the manufacture alcohol (ethanol). Although the FDA has recommended that such products should contain less than 630 ppm of methanol, it is only a temporary measure established specifically to regulate such products during the current COVID-19 pandemic and hence is not strictly regulated.

Objective:

This study aims to detect and quantify the level of methanol in alcohol-based products. However, some manufacturers unethically add methanol in their products and promote them as methanol-free. Besides, they do not provide proficiency and toxicity test results. Therefore, these kinds of products need to be analyzed to determine if they are acceptable to use.

Method:

This study qualitatively and quantitatively investigates the amount of methanol in commercial alcohol-based products using a newly developed headspace gas chromatography/mass spectrometry method. Moreover, alcohol beverages which contain methanol were analyzed to be compared with the levels of methanol in alcohol-based products and determine if their methanol levels are acceptable.

Results:

Methanol concentrations in gel-type hand sanitizers (517 ppm) and mouthwashes (202 ppm) were similar to those in white wine (429 ppm) and beer (256 ppm), respectively, while that of aqueous-type hand sanitizers (1139 ppm) is 1.5 times more than that of red wine (751 ppm).

Conclusion:

Methanol levels in most of the alcohol-based products did not exceed the FDA-recommended limit.

Development of Diketopyrrolopyrrole-Based Smart Inks by Substituting Ionic Pendants and Engineering Molecular Packing Structures

A series of diketopyrrolopyrrole (DPP) luminogen amphiphiles were newly designed and synthesized by a single-step anionic exchange reaction for controlling the photoluminescence properties in both solution and solid states. Multicolor emission in response to thermal, mechanical, and chemical stimuli was successfully demonstrated by engineering well-defined supramolecular assemblies. Phase transformation from the metastable amorphous solid to the stable orthorhombic crystal of [DP-Im][Br] provided the reversibly patternable light emission. Self-organization into the smectic crystalline phase of [DP-Im][TFSI] allowed us to show the linearly polarized light emission. By simultaneously applying [DP-Im][Br] and [DP-Im][TFSI], we demonstrated the fabrication of smart sensors for packaging of food or vaccines that can detect thermal attacks.

Bioinspired, Cholesteric Liquid-Crystal Reflectors with Time-Controlled Coexisting Chiral and Achiral Structures

The twisted structures of the chitin-based cuticle of beetles confer specific optical characteristics on them. Intrigued by the observation of Bragg gratings with a depth-dependent periodicity in the cuticle of Chrysina beetles, we determine the experimental conditions leading to their transcription into cholesteric liquid-crystal oligomers. We correlate the optical properties of reflectors thus produced with their internal morphology, as observed by transmission electron microscopy. With the use of a single parameter, thermal annealing time, the reflection color is made time-tunable. Different spectral bands and reflection colors from golden yellow to NIR are available, and the irreversibility of the final color is reached at the end. On the basis of the design concept and these properties, these hybrid chiral-achiral materials inspire the fabrication of smart reflective labels. When encapsulated in the package of a product to be kept under cold conditions, the label records the history of the product conservation. Two kinds of information based on color changes are recorded as follows: qualitative information reporting that the product was kept outside of the specified storage temperature and quantitative information giving an indication of the time elapsed since the temperature exceeded the storage temperature of the product.