Abstract RNA and DNA biomarkers serve as diagnostic molecules for detecting a specific disease by a variety of methods and technologies. A common approach is based on a fluorescence readout signal generated after hybridization to a target nucleic acid sequence. One such technology is termed Forced-Intercalation Peptide Nucleic Acid (FIT-PNA). In the FIT-PNA design, one of the nucleobases of the PNA sequence is replaced by a fluorescent molecule termed as “surrogate base.” One of the more common fluorophores explored to date is the cyanine dye, Thiazole Orange (TO). In this report, we have designed TO-based FIT-PNAs that are chemically modified with a cyclopentane backbone (cpTO). In addition, we have introduced to the FIT-PNA design either a cyclopentane T (cpT) or a tetrahydrofuran T (THFT) flanking cpTO. In a model system (11-mer FIT-PNA), we observe a dramatic increase in fluorescence (with DNA or RNA complementary sequences) for both cpT-cpTO and THFT-cpTO FIT-PNAs in comparison to the unmodified counterpart (T-TO FIT-PNA). Moreover, sequence specificity for an RNA sequence with a single mismatch is dramatically improved for both cpT-cpTO and THFT-cpTO FIT-PNAs. Molecular simulations of both cpT-cpTO FIT-PNA and TO (unmodified) FIT-PNA further support the superiority of these chemically modified nucleic-acid probes, as corroborated by a greater π–π stacking of cpTO in the PNA-RNA duplex. Lastly, a cpT-cpTO FIT-PNA targeting the oncogenic long noncoding RNA ANRIL (antisense noncoding RNA in the INK4 locus) was shown to detect this RNA biomarker in ovarian cancer cells (OVCAR-8). This probe was superior to the unmodified TO-based FIT-PNA, highlighting the added value of chemically modified TO FIT-PNAs as means for obtaining highly sensitive and sequence-specific nucleic acid sensors.

Cell penetrating thyclotides (CPTs) are synthetic molecules that promote highly efficient cellular uptake and endosomal escape of bioactive peptides. While peptides are valuable as medicinal agents, their translation to therapies is often limited by their inability to cross cell membranes. CPTs have a unique combination of chiral tetrahydrofurans and polar sidechains within a molecular scaffold that can be optimized to efficiently deliver peptide cargo into cells. The cellular uptake and endosomal escape of two peptides with anticancer biological activities but low bioavailabilities were remarkably improved after conjugation to a CPT. Using CPTs to overcome barriers to cellular uptake represents a new direction for the intracellular delivery of bioactive molecules, and will accelerate drug development for new medical therapies.

The expanding use of Flash circuits in high-radiation environments, such as aerospace, increases its susceptibility to performance degradation or failure due to total ionizing dose (TID) effects. To enhance the TID radiation tolerance of Flash circuits, this study investigates a bismuth oxide/epoxy resin (Bi2O3/EP) composite coating. The coating was used for radiation hardening of commercial Flash circuits and subjected to comprehensive reliability testing, including mechanical, thermal, and electrical assessments, followed by TID irradiation experiments. Results demonstrate that the Bi2O3/EP coating exhibits excellent adhesion and environmental durability, successfully meeting all reliability criteria. Critically, the coating provides effective shielding against radiation within GEO cabin, significantly improving TID tolerance up to 300 krad(Si), exceeding conventional requirements for space applications. This work validates Bi2O3/EP as a promising low-cost, lightweight component-level radiation hardening strategy for Flash memory in extreme space environments.

Nature relies on nucleobase complementation to store and deploy genetic information. Peptide nucleic acids (PNAs) are nucleic acid analogues widely adopted for their high biological stability and robust sequence-specific nucleobase complementation properties. Here, we report a strategy to modify PNAs, affording bioorthogonal analogues that hybridize to one another without binding to complementary nucleic acids under physiological conditions. Chiral cyclopentane and tetrahydrofuran rings are incorporated into the PNA backbone to promote left-handed helical conformations, opposite to the right-handed helix adopted by DNA and RNA. The binding of left-handed PNAs (LH-PNAs) to DNA and RNA is evaluated using melting temperature (Tm) experiments and circular dichroism (CD) experiments. The binding of LH-PNAs in the presence of right-handed PNA (RH-PNA) and DNA is examined using analytical HPLC. Results suggest that only a few left-handed substitutions at the center of PNA sequences attain bioorthogonal properties. These findings may facilitate the use of LH-PNAs for a range of applications in bioorthogonal chemical space. Peptide nucleic acids (PNAs) are valued for their stability and strong binding to complementary sequences, yet their interactions with natural nucleic acids can limit applications. Here, the authors introduce cyclic chiral modifications to PNAs, creating left-handed analogues that selectively recognize other left-handed complementary PNA strands while avoiding natural DNA and RNA. These left-handed PNAs broaden the toolkit for bioorthogonal applications in chemical biology.

Peptide nucleic acids (PNAs) have attracted considerable attention in biomedical research due to their strong binding properties toward complementary oligonucleotides and complete resistance to enzymatic degradation. However, the applications of PNAs may be limited by poor cellular uptake and low water solubility. To this end, we introduced rigid tetrahydrofurans (thfs) into the PNA backbone to develop tetrahydrofuran peptide nucleic acids (thfPNAs) with significant improvements in binding properties, water solubility, and cellular uptake. Herein we describe the protocols for preparing thfPNA monomers, thfPNA oligomers, and methods to study their cellular uptake using FACS experiments.

FIT-PNAs (forced intercalation-Peptide Nucleic Acids) are promising RNA sensors due to the enhanced fluorescence gained by such molecules upon RNA hybridization. In this report we describe a chemical approach that leads to unprecedented brightness for a FIT-PNA where the neighbouring Guanine base (G) to the fluorophore (a.k.a. surrogate base) is chemically modified with a cyclopentane (cp) backbone and is N-methylated, leading to a positively charged (G+) base. A series of G modified bases (G+, cpG, and cpG+) were introduced as the neighbouring base to BisQ (surrogate base) in 15-mer FIT-PNAs designed to sense the oncogenic long-noncoding RNA, colon cancer associated transcript 1 (lncRNA CCTA-1). Using synthetic RNA, the combination denoted as cpG+ led to a two-fold increase in brightness (BR = 16.9) compared to the unmodified G base (BR = 8.4). Introducing a G mismatch in RNA sequence that is opposite to the G base (G, G+, cpG, or cpG+) in the FIT-PNA, led to an increase in fluorescence that was not observed for synthetic DNA. Molecular simulations confirmed these observations and further correlated fluorescence data for FIT-PNAs with synthetic DNA and RNA with/out mismatches. Importantly, in ovarian cancer cells overexpressing CCAT1, only the cpG+ modified FIT-PNA produced a bright fluorescent signal, confirmed by FACS and confocal microscopy. Our results demonstrate that strategic chemical modifications of the neighboring G base in FIT-PNA significantly enhance their brightness and specificity for RNA detection in biological systems.

The high-cost problem in radiation hardening for specific types of aerospace integrated circuits can be effectively addressed by adopting composite coatings, which demonstrate advantages such as low cost, lightweight, and broad versatility. This study analyzed the radiation environment within spacecraft interiors and investigated the mechanisms of electron radiation protection by coatings, highlighting the performance advantages of Bi2O3/epoxy resin (Bi2O3/EP) composites. A co-simulation model of “coating + circuit” was established to determine the radiation protection efficiency (RPE) under various electron energies, coating compositions, and thicknesses. Furthermore, a calculation method for the comprehensive RPE under continuous electron spectra was developed. The study proposed a novel evaluation metric, the shielding effectiveness comprehensive index (SECI), which incorporates both RPE and areal density. FLASH circuit samples packaged with Bi2O3/EP composite coatings were fabricated and subjected to thermal-mechanical-electrical reliability testing. Electron irradiation experiments on both the standalone coatings and the package-hardened circuits were conducted, with coating results validating the high accuracy of the simulation model. Additionally, a novel RPE evaluation method based on the intrinsic electrical parameters variations (IEPV) of circuit was introduced. This method successfully determined the RPE of coatings against 5 MeV electrons in the practical circuit application state, achieving a simulation error of less than 25%. The SECI and IEPV evaluation methodologies proposed herein provide valuable technical guidance for designing protective coatings for circuits and enable effective assessment of the radiation resistance for package-hardened circuits.

The evolution of drug resistance to many antimalarial drugs in the lethal strain of malaria (Plasmodium falciparum) has been a great concern over the past 50 years. Among these drugs, artemisinin has become less effective for treating malaria. Indeed, several P. falciparum variants have become resistant to this drug, as elucidated by specific mutations in the pfK13 gene. This study presents the development of a diagnostic kit for the detection of a common point mutation in the pfK13 gene of P. falciparum, namely, the C580Y point mutation. FIT-PNAs (forced-intercalation peptide nucleic acid) are DNA mimics that serve as RNA sensors that fluoresce upon hybridization to their complementary RNA. Herein, FIT-PNAs were designed to sense the C580Y single nucleotide polymorphism (SNP) and were conjugated to biotin in order to bind these molecules to streptavidin-coated plates. Initial studies with synthetic RNA were conducted to optimize the sensing system. In addition, cyclopentane-modified PNA monomers (cpPNAs) were introduced to improve FIT-PNA sensing. Lastly, total RNA was isolated from red blood cells infected with P. falciparum (WT strain - NF54-WT or mutant strain - NF54-C580Y). Streptavidin plates loaded with either FIT-PNA or cpFIT-PNA were incubated with the total RNA. A significant difference in fluorescence for mutant vs WT total RNA was found only for the cpFIT-PNA probe. In summary, this study paves the way for a simple diagnostic kit for monitoring artemisinin drug resistance that may be easily adapted to malaria endemic regions.

Ovarian cancer (OC) is one of the most lethal gynecologic cancers that is typically diagnosed at the very late stage of disease progression. Thus, there is an unmet need to develop diagnostic probes for early detection of OC. One approach may rely on RNA as a molecular biomarker. In this regard, FLJ22447 lncRNA is an RNA biomarker that is over-expressed in ovarian cancer (OC) and in cancer-associated fibroblasts (CAFs). CAFs appear early on in OC as they provide a metastatic niche for OC progression. FIT-PNAs (forced intercalation-peptide nucleic acids) are DNA analogs that are designed to fluoresce upon hybridization to their complementary RNA target sequence. In recent studies, we have shown that the introduction of cyclopentane PNAs into FIT-PNAs (cpFIT-PNA) results in superior RNA sensors. Herein, we report the design and synthesis of cpFIT-PNAs for the detection of this RNA biomarker in living OC cells (OVCAR8) and in CAFs. cpFIT-PNA was compared to FIT-PNA and the cell-penetrating peptide (CPP) of choice was either a simple one (four L-lysines) or a CPP with enhanced cellular uptake (CLIP6). The combination of CLIP6 with cpFIT-PNA resulted in a superior sensing of FLJ22447 lncRNA in OVCAR8 cells as well as in CAFs. Moreover, incubation of CLIP6-cpFIT-PNA in OVCAR8 cells leads to a significant decrease (ca. 60%) in FLJ22447 lncRNA levels and in cell viability, highlighting the potential theranostic use of such molecules.

MERTK and AXL are members of the TAM (TYRO3, AXL, MERTK) family of receptor tyrosine kinases that are aberrantly expressed and have been implicated as therapeutic targets in a wide variety of human tumors. Dual MERTK and AXL inhibition could provide antitumor action mediated by both direct tumor cell killing and modulation of the innate immune response in some tumors such as nonsmall cell lung cancer. We utilized our knowledge of MERTK inhibitors and a structure-based drug design approach to discover a novel class of macrocyclic dual MERTK/AXL inhibitors. The lead compound 43 had low-nanomolar activity against both MERTK and AXL and good selectivity over TYRO3 and FLT3. Its target engagement and selectivity were also confirmed by NanoBRET and cell-based MERTK and AXL phosphorylation assays. Compound 43 had excellent pharmacokinetic properties (large AUC and long half-life) and mediated antitumor activity against lung cancer cell lines, indicating its potential as a therapeutic agent.

航天集成电路是空间电子系统的核心部件，抗辐射加固技术是保障航天集成电路在空间环境可靠工作的核心技术。随着电路特征尺寸缩小至纳米尺度，单粒子效应逐渐成为制约航天集成电路抗辐射能力的最主要因素。北京微电子技术研究所团队以设计加固方式作为航天集成电路抗辐射研制技术路线，基于在重离子加速器上获取的大量单粒子试验数据，提出新工艺新器件的单粒子效应试验评估新方法，开展测试分析技术和辐射效应规律研究，为加固技术研究提供准确基础信息，检验设计加固技术有效性，揭示单粒子辐射损伤机制，为优化加固提供指导，最终形成高可靠、长寿命航天集成电路产品提供了关键支撑。

Selective incorporation of conformational constraints into thyclotides can be used to modulate their binding to complementary oligonucleotides, increase polarity, and optimize uptake into HCT116 cells without assistance from moieties known to promote cell uptake. The X-ray structure and biophysical studies of a thyclotide-DNA duplex reveal that incorporation of tetrahydrofurans into an aegPNA backbone promotes a helical conformation that enhances binding to complementary DNA and RNA. Selective incorporation of tetrahydrofurans into the aegPNA backbone allows polarity to be increased incrementally so that uptake into HCT116 cells can be optimized. The enhanced binding, polarity, and cellular uptake properties of thyclotides were used to demonstrate effective inhibition of microRNA-21 in HCT116 cells.

Astronautic integrated circuits face total ionizing dose effects in near-Earth orbit space, the main source is the radiation effect produced by space particles such as electrons in the Van Allen radiation belt. The current industry standard ground-based total ionizing dose simulation tests are mainly conducted on Co60 radiation sources. However, electrons differ from photons in the total dose radiation damage mechanism and damage effect. In this paper, by conducting total ionizing dose of electron test and data analysis, and construct an alanine-based electron absorption dose model by software, summarizing electron radiation damage mechanism and law, obtaining relative dose absorption ratio coefficients under different energy electron irradiation, and proposing considerations for the test of total ionizing dose of electron.

The effect of the total ionizing dose (TID) on the static random access memory (SRAM) is conducted on the 60Co radioactive source in the China Institute of Atomic Energy. The study explores the influence of the device process size, dose rate, temperature and total dose on TID. The results indicated that within a certain range, the dose rate had little influence on the TID of the device. The larger the characteristic size of the device, the greater TID effect, while the higher temperature, the weaker the total dose effect. In addition, the typical dose rate and the uniformity of the source are achieved. The research of the paper provide an insight into radiation hardening, particularly in the aerospace and the nuclear industries.

Correction for 'Cyclopentane FIT-PNAs: bright RNA sensors' by Odelia Tepper et al., Chem. Commun., 2021, 57, 540-543, https://doi.org/10.1039/D0CC07400D.

The ionizing radiation effects of static total dose and dynamic total dose on a commercial magnetoresistive random access memory（MRAM） are studied. The total dose test study of commercial MRAM is conducted at the 60 Co γ radiation source of China National Institute of Metrology, including different test vectors, different test modes, whether there is a protective layer or not, and the total dose test study under power-on and power-off modes. The results show that the anti total dose capability of the chip under static mode is the worst, followed by dynamic read mode and dynamic write mode, and the no power mode is the best which shows that the magnetic storage unit has a strong anti irradiation capability. For different test vectors, the following conclusions are drawn: in static mode, the radiation resistance FF＜oblique triangle ＜00 while in the dynamic read mode, the radiation resistance FF＜00＜oblique triangle. The anti total dose effect of the circuit with shielding layer is 23 times higher than that of the circuit without shielding layer. The data bit errors of the chip under different test modes are analyzed and explained, and the test results provide guidance and reference for the reinforcement design of aerospace MRAM chips.

针对一款百万门级0.18μm互补金属氧化物半导体(0.18μm CMOS)工艺抗辐射加固的微处理器电路,提出了采用TCAD仿真建模技术对加固电路开展瞬时剂量率效应研究的方法,仿真结果表明通过保护环结构加固设计,可有效提升电路的抗瞬时剂量率效应性能,并利用瞬时剂量率辐射源进行了仿真有效性的试验验证.结果表明,采用TCAD仿真手段得到的瞬时光电流峰值与试验得到的光电流峰值误差小于5％,证实了仿真研究电路瞬时剂量率效应方法的有效性.

The wild-type p53 induced phosphatase 1 (Wip1), a member of the serine/threonine-specific PP2C family, is overexpressed in numerous human cancers. Wip1 dephosphorylates p53 as well as several kinases (such as p38 MAPK, ATM, Chk1, and Chk2) in the DNA damage response pathway that are responsible for maintaining genomic stability and preventing oncogenic transformation. As a result, Wip1 is an attractive target for synthetic inhibitors that could be further developed into therapeutics to treat some cancers. In this study, we report a series of alkyl-substituted N-methylaryl-N'-aryl-4-aminobenzamides and their inhibitory activity of the Wip1 phosphatase. A straightforward synthetic route was developed to synthesize the target compounds from commercially available starting materials. Three different portions (R1, R2, R3) of the core scaffold were extensively modified to examine structure-activity relationships. This study revealed interesting trends about a new molecular scaffold to inhibit Wip1.

A cell-level radiation hardening by design (RHBD) method based on commercial processes of single event transient (SET) and single event upset (SEU) is proposed in this paper, in which new radiation-hardened D-type flip-flops (DFFs) are designed. An application-specific integrated circuit (ASIC) of a million gates level is developed based on DFFs, and SEU and single event functional interruption (SEFI) heavy-ion radiation tests are carried out. The experimental results show that the new DFF SEU ability is increased by 63 times compared with the DICE-designed DFF, and is three orders of magnitude higher than the redundantly designed DFF. The SEFI ability of the ASIC designed by the new DFF is 2.6 times higher than the circuit hardened by the TMR design.