Latest ArticlesBiomimetic scaffolds present the promising potential for bone regeneration. As a natural gel-like traditional food, tofu with porous architecture and proved biological safety indicated a good potential to be a natural scaffold and easy to be improved by surface modification. Hereon, we fabricated the tofubased scaffolds and systematically explored the potential for bone tissue engineering. In addition, the collagen has been introduced by simple coating to further enhance the surface compatibility of the tofubased scaffold in bone regeneration. The results showed that the tofu-based scaffolds possessed good porous structure and cytocompatibility. Notably, the tofu-based scaffolds could improve the expression of osteogenesis-related genes and proteins, leading to better bone regeneration after 2 months of implantation. All the results indicated that tofu would become an outstanding sustainable natural porous scaffold for bone regeneration with excellent bioactivities.
Fragrances are widely used in many aspects of our lives. They cannot only make people happy, but also treat many diseases. However, excessively fast evaporation rate is one of the main obstacles to the use of spices. In this study, mesoporous silica nanorods (MSNRs) and hollow mesoporous silica nanorods (HMSNRs) were prepared to encapsulate eugenol. These two nano-fragrances were named eugenol@MSNRs and eugenol@HMSNRs, respectively. The morphologies, size, interior structures and pore performances of MSNRs and HMSNRs. Besides, the performances of encapsulation and fragrance release of eugenol@MSNRs and eugenol@HMSNRs were compared and analyzed. The results showed that eugenol@HMSNRs encapsulated more fragrance and were faster to encapsulate compared with eugenol@MSNRs. Both the release rates of eugenol from eugenol@MSNRs and eugenol@HMSNRs were slow. But the eugenol was released from eugenol@MSNRs more slowly.
Polypeptides are one kind of promising biodegradable and biocompatible biomedical polymers with the structural units of various α-amino acids. Polypeptides were first polymerized by the ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCAs) by Leuchs and Hermann in 1906. In the past decades, several effective strategies, including the selection of initiators, the adjustment of reaction conditions, and the introduction of catalysts, have been reported to improve the controllability of the ROP of various α-amino acid NCAs to synthesize different polypeptides with precise chemical structures and low polydispersity indexes. In this Review, the strategies, mechanisms, challenges, and opportunities for controlled synthesis of polypeptides by the ROP of different α-amino acid NCAs have been declared.
Nitriles are widely existed in many bioactive compounds, and they can be easily transformed into other functional groups. Therefore, the synthesis of nitriles under cyanide-free conditions is of significant importance. Recent advances for the synthesis of nitriles through photoinduced C-C bond cleavage of cycloketone oximes classified by the type of C-X bond forming are summarized. Various compounds possessing nitriles can be efficiently accessed via this method.
A highly sensitive fluorescent sensor ZnDN was designed, synthesized and used for tracking intracellular zinc ions in various living cells and direct imaging of prostatic tissue in mice. ZnDN was prepared from the heterocyclic-fused naphthalimide fluorophore, and the zinc receptor, N, N-bis(2-pyridylmethyl)ethylenediamine (BPEN). Upon addition of Zn2+ to the solutions of ZnDN, a remarkable fluorescence enhancement was observed, which could be attributed to the photo-induced electron transfer (PET) mechanism. Since ZnDN exhibited high sensitivity toward Zn2+ in phosphate buffer solution, with a limit of detection of 4.0×10-9 mol/L, it was further applied for the imaging of exogenous and endogenous Zn2+ in different living cells. Living cells imaging experiments suggested that ZnDN could image the changes of intracellular free zinc ions, and could be used for two-photon imaging. Moreover, flow cytometry suggested that ZnDN could distinguish cancerous prostate cells from normal cells. Animal experiments indicated that ZnDN had the potential in imaging prostate tissue in vivo.
Triazolopyridines are an important kind of fused-ring compounds. A HOCl-promoted triazolopyridine formation strategy is reported here for the first time in which hypochlorous acid (HOCl) mildly and efficiently promotes the formation of 1, 2, 4-triazolo[4, 3-a]pyridines NT1-NT6 from various 2-pyridylhydrazones N1-N6. N6, a rhodol-pyridylhydrazone hybrid, was developed into a fluorescent probe for the selective detection of HOCl, and successfully applied to probe endogenous HOCl in living cells and zebrafish in situ and in real time. The present intramolecular cyclization reaction is selective and atom-economical, thereby not only providing an important approach for the convenient synthesis of triazolopyridines, but also offering a general strategy for sensitive, selective and biocompatible detection of endogenous HOCl in complex biosystems.
Monitoring dynamics of mitochondria has become an essential approach to explore the function of mitochondria in living cells with the emergence of super-resolution fluorescence microscopy. However, long-term super-resolution imaging of mitochondria is still challenging due to the lack of photostable fluorescent probes and stable mitochondria-specific markers which are not affected by the changes of mitochondrial membrane potential. Here, we introduce a method for long-term imaging mitochondrial dynamic through the SNAP-tag fluorogenic probe based on 4-azetidinyl-naphthalimide derivatives. Using structured illumination microscopy (SIM), we observed the fusion and fission of mitochondria over a course of 16 min at 109 nm resolution. Furthermore, the interactions as well as fusion between mitochondria and lysosomes were studied during mitophagy at the nanoscale. Convincingly, the combination of SNAP-tag fluorogenic probes and super-resolution fluorescence microscopy will offer a new way to monitor dynamic mitochondria in living cells.
Palladium(0) as one of the vital transition metals, is employed in numerous industries, such as drug synthesis, aerospace high-tech field and automobile industry. When the Pd(0) enter into the body, it will bind with thiol-containing amino acids, DNA, RNA, and other biomolecules damaging to human health. Thus, developing a novel tool for monitoring and imaging of Pd(0) in vivo is very urgent. In the work, based on a intramolecular charge transfer (ICT) mechanism a two-photon fluorescent probe NIPd had been designed and synthesized for the recognition Pd(0). In vitro experiments data displayed that probe NIPd exhibited a 13-fold fluorescent increase for Pd(0) in 30 min in the aqueous solution with a detection limit of 16 nmol/L. It also showed the outstanding selectivity and antijamming performance. More importantly, NIPd could be served as a two-photon fluorescent probe for real-time monitoring Pd(0) in living cells and mice.
The different oxidation states of sulphur atom play a significant role on functional materials. In this work, a aryl-thioether and its sulphone substituted benzo[c][1, 2, 5]oxadiazole dyes were synthesized and utilized to determine thiol-containing amino acids. The result of selectivity experiments showed they detected the cysteine and homocysteine under physiological condition with negligible interference from other amino acids. In comparison to the thioether dye, the sulphone-based dye exhibited much faster response time for Cys and Hcy. However, the sulphone restricted its thiol-reactivity and bioimaging performance in living cells. By reducing the oxidation state of sulphur atom, we amazedly found that the sulfoxide-based dye still maintained high selectivity ultrafast response time for Cys/Hcy under physiological condition. It was worth mentioning that it also had high reactivity and good bioimaging performance that sulfone compounds did not have.
Thioxo/dithioxo-naphthalimide is a class of rarely visited fluorophore, first synthesized in 1999. Facile chemistry was devised to achieve mono or dual thionation of the two carbonyl groups of 1, 8-naphthalimide. Thionation effectively shifts absorption maximum to longer spectral wavelength, significantly increase absorption coefficients, and dramatically enhances intersystem crossing efficiency with respect to their oxo-analogues. They were first explored as potent photocleavers to induce DNA strand break and novel photosensitizers for photodynamic therapies. In recent years, the unique chemistry of thioxo groups has been harnessed to achieve new applications, such as fluorescent sensors for heave metal ions. These unique photochemical and photophysical characteristics revitalize them intriguing functional molecules to investigate. In this short review, we wish to revisit their first discovery, facile synthesis, and the endeavors on the use of thioxo/dithioxo-naphthalimides for novel chemical and biomedical applications.
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