Epoxy Resins With Controllable "Thermally Conductive-Self-Healing" Synergies: a New Material to Meet the Needs of Flexible Electronic Devices.

With the popularization of 5G technology and artificial intelligence, thermally conductive epoxies with self-healing ability will be widely used in flexible electronic materials. Although many compounds containing both performances have been synthesized, there is little systematic theory to explain the coordination mechanism. In this paper, alkyl chains of different lengths were introduced to epoxies to discuss the thermally conductive, the self-healing performance, and the synergistic effect. A series of electronic-grade biphenyl epoxies (4,4'-bis(oxiran-2-ylmethoxy)-1,1'-biphenyl (1), 4,4'-bis(2-(oxiran-2-yl)ethoxy)-1,1'-biphenyl (2), 4,4'-bis(3-(oxiran-2-yl)propoxy)-1,1'-biphenyl (3), and 4,4'-bis(4-(oxiran-2-yl)butoxy)-1,1'-biphenyl (4) were synthesized and characterized. Furthermore, they were cured with decanedioic acid to produce polymers. Results showed that alkyl chains can both affect the two properties, and the epoxies suitable for specific application scenarios can be prepared by adjusting the length of alkyl chains. In terms of thermal conductivity, compound 1 was a most promising material. However, compound 4 was expected to be utilized in flexible electronic devices because of its acceptable thermal conductivity, self-healing ability, transparency, and flexibility.

Monitoring the Cellular Delivery of Doxorubicin-Cu Complexes in Cells by Fluorescence Lifetime Imaging Microscopy.

In the prodrug research field, information obtained from traditional end point biochemical assays in drug effect studies could provide neither the dynamic processes nor heterogeneous responses of individual cells. In situ imaging microscopy techniques, especially fluorescence lifetime imaging microscopy (FLIM), could fulfill these requirements. In this work, we used FLIM techniques to observe the entry and release of doxorubicin (Dox)-Cu complexes in live KYSE150 cells. The Dox-Cu complex has weaker fluorescence signals but similar lifetime values as compared to the raw Dox, whose fluorescence could be released by the addition of biothiol compound (such as glutathione). The cell viability results indicated that the Dox-Cu compound has a satisfactory killing effect on KYSE150 cells. The FLIM data showed that free doxorubicin was released from Dox-Cu complexes in cytoplasm of KYSE150 cells and then accumulated in the nucleus. After 90 min administration, the fluorescence lifetime signals reached 1.21 and 1.46 ns in the cytoplasm and nucleus, respectively, reflecting the transformation and transportation of Dox-Cu complexes. In conclusion, this work provides a satisfactory example for the research of prodrug monitored by FLIM techniques, expanding the useful applications of FLIM technique in drug development.

Diketopyrrolopyrrole Amphiphile-Based Micelle-Like Fluorescent Nanoparticles for Selective and Sensitive Detection of Mercury(II) Ions in Water.

A technique for encapsulating fluorescent organic probes in a micelle system offers an important alternative method to manufacture water-soluble organic nanoparticles (ONPs) for use in sensing Hg2+. This article reports on a study of a surfactant-free micelle-like ONPs based on a 3,6-di(2-thienyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (TDPP) amphiphile, (2-(2-(2-methoxyethoxy)ethyl)-3,6-di(2-thiophyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (NDPP) fabricated to monitor Hg2+ in water. NDPP was synthesized through a simple one-step modification of a commercially available dye TDPP with a flexible and hydrophilic alkoxy. This study reports, for the first time, that TDPP dyes can respond reversibly, sensitively, and selectively to Hg2+ through TDPP-Hg-TDPP complexation, similar to the well-known thymine(T)-Hg-thymine(T) model and the accompanying molecular aggregation. Interestingly, transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirmed that, in water, NDPP forms loose micelle-like fluorescent ONPs with a hydrohobic TDPP portion encapsulated inside. These micelle-like nanoparticles offer an ideal location for TDPP-Hg complexation with a modest molecular aggregation, thereby providing both clear visual and spectroscopic signals for Hg2+ sensing. An estimated detection limit of 11 nM for Hg2+ sensing with this NDPP nanoparticle was obtained. In addition, NDPP ONPs show good water solubility and high selectivity to Hg2+ in neutral or alkalescent water. It was superior to most micelle-based nanosensors, which require a complicated process in the selection or synthesis of suitable surfactants. The determinations in real samples (river water) were made and satisfactory results were achieved. This study provides a low-cost strategy for fabricating small molecule-based fluorescent nanomaterials for use in sensing Hg2+. Moreover, the NDPP nanoparticles show potential ability in Hg2+ ion adsorption and recognization of cysteine using NDPP-Hg composite particle.

Automatic In Situ Synthesis System for Polypeptide Biochip Based on Microfluidic Mixer.

Biochips have become a sophisticated analytical device in the fields of biochemical sensing and genetic analysis. However, the cumbersome preparation process and the high production cost limit the versatility of its application. Herein, we have developed an automated synthesis system for in situ preparation of biochip with peptide backbone based on the microfluidic mixer and micro reaction chamber. The microfluidic mixer was used as a key component to perform the real-time activation of the carboxylic groups, leading to an instant coupling reaction of monomers with high efficiency. The repeating synthesis procedure was realized without too much manual intervention with the help of flow control system based on programmable logical controller and LabVIEW. The real-time monitoring of synthesis process was realized using a low-cost solar cell coupled with simple ultraviolet absorption device. The photodeprotection experiment revealed that an exposure time of 4 min with 20 mW/cm2 ultraviolet (UV) light at 365nm was sufficient for the complete removal of 2-(2-nitrophenyl) propyloxycarbonyl (NPPOC) groups from the synthetic sites in N, N-dimethylformamide (DMF). The practical capability performance of this synthesis system was further demonstrated by the synthesis of four cycles of aminocaproic acid, and the stepwise yield of coupling was measured to be about 96%, which was comparable with the result from literature, and indicated that this system may provide a new alternative for low-cost in situ synthesis of biochip.

Film-Spotting chiral miniPEG-γPNA array for BRCA1 gene mutation detection.

Peptide nucleic acids array technology is a method of greatly increasing the throughput of laboratory processes to efficiently perform large-scale genetic tests. Diethylene glycol-containing chiral γPNA (miniPEG-γPNA) is considered to be the best PNA derivative and one of the best candidates for gene detection, because it can hybridize DNA with greater affinity and sequence selectivity than DNA and ordinary aminoethylglycyl PNA (aegPNA). Herein, miniPEG-γPNA probes are synthesized by 9-fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS) in a mild condition, and a new biochip fabrication method "Film-Spotting" is invented, by which γPNA arrays with regular pattern, uniform luminance, and very low fluorescence background are obtained easily and cheaply. The miniPEG-γPNA array can effectively distinguish the full matched and mismatched targets in SSarc buffer, serum and urine, and the detection limit of complementary DNA is less than 5.97 nM. A miniPEG-γPNA array for BRCA1 gene mutation (3099delT) detection is also fabricated with a very good detection performance. This work provides an effective avenue for the diagnosis of breast cancer biomarker and expands the application of miniPEG-γPNA in the field of biochip.

Recognition Mechanisms and Applications of Peptide Nucleic Acids Targeting Double-stranded DNA.

Targeting double-stranded DNA (dsDNA) with high affinity and specificity has become a hot topic in biochemistry and molecular biology research. Gene diagnosis and therapy, DNA manipulation, and gene expression regulation could be achieved based on certain recognition principles through specific interactions between dsDNA and natural nucleotides or synthesized ligands. Some ligands (e.g., peptide nucleic acids (PNAs), triple helix-forming oligonucleotides (TFOs), oligopolyamides, and zinc-finger peptides) show sufficient affinity and specificity for targeting dsDNA sequences. PNA can simply synthesize and recognize dsDNA without sequence limitation under physiological conditions. This paper provides a review on the recognition mechanisms, influencing factors, and applications of the four recognition modes of PNA targeting dsDNA. These modes include triplex invasion, triplex binding, duplex invasion, and double duplex invasion. This paper also discusses the challenges to be addressed by future research to fully explore the potential of PNA probe design for specific dsDNA recognition.

Light-Directed Synthesis of High-Density Peptide Nucleic Acid Microarrays.

Peptide nucleic acids (PNAs) are a class of nucleic acid mimics that can bind to the complementary DNA or RNA with high specificity and sensitivity. PNA-based microarrays have distinct characteristics and have improved performance in many aspects compared to DNA microarrays. A new set of PNA monomers has been synthesized and used as the building blocks for the preparation of high density PNA microarrays. These monomers have their backbones protected by the photolabile group 2-(2-nitrophenyl)propyloxy carbonyl (NPPOC), and their exocyclic amino groups protected by amide carbonyl groups. A light-directed synthesis system was designed and applied to the in situ synthesis of a PNA microarray with a density of over 10,000 probes per square centimeter. This PNA microarray was able to detect single and multiple base-mismatches correctly with a high discrimination ratio.

A review: fabrications, detections and applications of peptide nucleic acids (PNAs) microarray.

Peptide nucleic acid (PNA) is a mimic of DNA that shows a high chemical stability and can survive the enzymatic degradation of nucleases and proteases. The superior binding properties of PNA enable the formation of PNA/DNA or PNA/RNA duplex with excellent thermal stability and unique ionic strength effect. The introduction of microarray makes it possible to achieve accurate, high throughput parallel analysis of DNA or RNA with a highly integrated and low reagents consuming device. This powerful tool expands the applications of PNA in genotyping based on single nucleotide polymorphism (SNP) detection, the monitoring of disease-related miRNA expression and pathogen detection. This review paper discusses the fabrications of PNA microarrays through in situ synthesis strategy or spotting method by automatic devices, the various detection methods for the microarray-based hybridization and the current applications of PNA microarrays.