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A temperature hysteretic transition, induced by supercooled water, is observed in both the electrical conductivity and Raman spectra signals of H2SO4-treated PEDOT:PSS.

Osteosarcoma (OS) is a primary malignant bone tumor that occurs mainly in adolescents. Researchers are devoting to develop combination therapy methods in a multifunctional nanoplatform for the treatment of osteosarcoma. The results of previous research have shown that up-regulation of miR- 520a-3p could induce anticancer effects in osteosarcoma. In order to improve the effect of gene therapy (GT), we attempted to carry miR-520a-3p in a multifunctional vector for comprehensive therapy. Fe 2 O 3 is a type of magnetic resonance imaging contrast that is widely used as a drug delivery agent. When coated with polydopamine (PDA), it can also be used as a photothermal therapy (PTT) agent (Fe 2 O 3 @ PDA). To deliver nanoagents targeted to a tumor site, folic acid (FA) conjugated with Fe 2 O 3 @PDA was manufactured as FA-Fe 2 O 3 @PDA. FA was chosen as the target molecule to enhance utilization and reduce toxicity of nanoparticles. However, the therapeutic efficacy of FA-Fe 2 O 3 -PDA combined with miR-520a-3p has not yet been studied. In this study, we synthesized FA-Fe 2 O 3 @PDA-miRNA and investigated the potential of combining PDA regulated PTT and miR-520a-3p regulated GT to kill osteosarcoma cells. The results indicated that down-regulation of interleukin 6 receptor (IL6R) by miR- 520a-3p and the photothermal ability of PDA could induce satisfactory anticancer effects in osteosarcoma, and the curative ratio was better than that used alone PTT or GT. Moreover, as a kind of T 2 magnetic contrast, miRNA-Fe 2 O 3 @PDA-FA can be used for magnetic resonance imaging (MRI). These findings indicated that miRNA-Fe 2 O 3 @PDA-FA is an effective anti-tumor nanovector for PTT combined with GT.

Heterostructures of quantum dots (QDs) and two-dimensional (2D) materials show promising potential for photodetection applications owing to their combination of high optical absorption and good in-plane carrier mobility. In this work, the performance of QD-2D photodetectors is tuned by band engineering. Devices are fabricated by coating MoS2 nanosheets with InP QDs, type-I core-shell InP/ZnS QDs, and type-II core-shell InP/CdS QDs. Comparative spectroscopic and photoelectric studies of different hybrids show that the energy band alignment and shell thickness can influence the efficiency of charge transfer (CT), energy transfer (ET), and defect-related processes between QDs and MoS2. Benefiting from efficient CT between the QDs and MoS2, a significant enhancement of responsivity and detectivity is observed in thick-shell InP/CdS QD-MoS2 devices. Our results demonstrate the feasibility of using core-shell QDs for regulating the ET and CT efficiency in heterostructures and highlight the importance of interface band design in QD-2D and other low-dimensional photodetectors.

Two-dimensional layered MoS2 has attracted tremendous attention because of its unique physical and chemical properties and promising application prospects. To further expand its applications to are...

Controllable tuning of electron–phonon coupling strength and excited state dynamics is important for the understanding of resonance Raman scattering in low-dimensional semiconductors. Here, we report a significant and reversible field-induced modulation in absolute resonance Raman intensity of quantum dots using ionic liquid gating. Meanwhile, a potential-dependent nonlinear relationship is present between Raman intensity and excitation power density. By exploring the parameter space within a time domain model, we find that the Raman intensity variation is mainly determined by the homogeneous linewidth. We further propose that the Fermi level positions and exciton species play key roles in the excited state decay rates.

The thickness dependence of the chemical and physical properties is one fundamental characteristic shared by many two-dimensional layered transition-metal dichalcogenides, including molybdenum disu...

This paper reports the design and facile synthesis of porous polynorbornenes containing a 4,4′-dialkoxy-azobenzene subunit (named Azo-POP-13 and Azo-POP-14). They were synthesized by the robust reductive azo-coupling polymerization of the Ring-Opening-Metathesis-Polymerization (ROMP) product on bis-para-nitrophenylether of the norbornene diol. The polymerization rate of exo-NBNPE (kapp = 18.7 × 10−2 s−1) is faster than that of endo-NBNPE (kapp = 3.64 × 10−2 s−1). The as-synthesized Azo-POP-13 was found to selectively adsorb 4-nitrophenol (4-NP) over 4-aminophenol (4-AP) in water, with a selectivity up to 14.6 and good recyclability.

Biofunctionalized quantum dots (QDs) are effective target fluorescent labels for bioimaging. However, conventional synthesis of biofunctionalized I-III-VI core-shell CuInS2/ZnS QDs requires complex bench-top operations, resulting in limited product performance and variety, and is not amenable to a 'one-step' approach. In this work, we have successfully demonstrated a fully automated method for preparing denatured bovine serum albumin (dBSA)-CuInS2/ZnS QDs by introducing microfluidic (MF) chips to synthesize biofunctionalized QDs, hence establishing a 'one-step' procedure. We have also studied and optimized the reaction synthesis parameters. The emission wavelength of the dBSA-CuInS2/ZnS QDs is located in the near-infrared range and can be tuned from 650 to 750 nm by simply varying the reaction parameters. In addition, the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs have a long average fluorescence lifetime of 153.76 ns and a small particle size of 5 ± 2 nm. To demonstrate the applicability of the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs in bioimaging studies, we modified the QDs with folic acid and hyaluronic acid, and then performed target bioimaging and cytotoxicity tests on macrophages, liver cancer cells and pancreatic cancer cells. The cell images show that the red emission signals originate from the QDs, which indicates that the dBSA-CuInS2/ZnS QDs prepared by the MF approach are suitable optical contrast agents for target bioimaging. This 'one-step' MF-based QD synthesis approach could serve as a rapid, cost-effective, and small-scale nanocrystal production platform for complex QD formulations for a wide range of bioapplications.

Heterostructures of quantum dots (QDs) and two-dimensional (2D) materials show promising potential for photodetection applications owing to their combination of high optical absorption and good in-plane carrier mobility. In this work, the performance of QD-2D photodetectors is tuned by band engineering. Devices are fabricated by coating MoS

With a focus on disease prevention and health promotion, a reactive and disease-centric healthcare system is revolutionized to a point-of-care model by the application of wearable devices. The convenience and low cost made it possible for long-term monitoring of health problems in long-distance traveling such as flights. While most of the existing health monitoring systems on aircrafts are limited for pilots, point-of-care systems provide choices for passengers to enjoy healthcare at the same level. Here in this paper, an airline point-of-care system containing hybrid electrocardiogram (ECG), breathing, and motion signals detection is proposed. At the same time, we propose the diagnosis of sleep apnea-hypopnea syndrome (SAHS) on flights as an application of this system to satisfy the inevitable demands for sleeping on long-haul flights. The hardware design includes ECG electrodes, flexible piezoelectric belts, and a control box, which enables the system to detect the original data of ECG, breathing, and motion signals. By processing these data with interval extraction-based feature selection method, the signals would be characterized and then provided for the long short-term memory recurrent neural network (LSTM-RNN) to classify the SAHS. Compared with other machine learning methods, our model shows high accuracy up to 84–85% with the lowest overfit problem, which proves its potential application in other related fields.

Charge transfer at the interface is important for the optoelectronic and photochemical applications of quantum dot-two-dimensional material (QD-2D) hybrids. In this work, Raman spectroscopy was exp...

To evaluate the dynamic contrast-enhanced MRI parameters for monitoring the neoadjuvant chemotherapy (NAC) response in osteosarcoma prospectively. A total of 19 patients with osteosarcoma were recruited and underwent two dynamic contrast-enhanced MRI (DCE-MRI) examinations before and after chemotherapy. Patients with ≥ 90% tumor necrosis were defined as responders (10 patients), and those

To understand the qualities of Western civilization and its modernity, to think about the future of humanity, and to understand how modern science was gestated in Western civilization: in t...

Objective The purpose of this study was to find out the important lncRNA-miRNA-mRNA axis and pathway in osteosarcoma (OS) through bioinformatics analysis and verify the biological functions of lncRNA/miRNA/mRNA in OS through in vitro and in vivo assays. Methods The differential expression mRNAs and lncRNAs were identified through microarray analysis, and the altered pathways were identified by GSEA. The Pearson Coefficient was used to analyze the correlations between mRNAs and lncRNAs. Kaplan-Meier survival analysis was preformed using patient information in GEO database. Their target miRNAs were predicted by Targetscan and miRanda database and confirmed by dual luciferase reporter assay. QRT-PCR were utilized to detected the relative expressions of mRNAs, miRNAs and lncRNAs. The expressions of IL6R protein and pathway related proteins were detected by western blot. OS cell viability, migration and apoptosis were determined through MTT assay, Transwell assay and flow cytometry. Tumor formation in nude mice verified the influence of LINC01116 in vivo. Results The Jak-stat signaling pathway was activated in OS tissues. LINC01116 expression was positively correlated with IL6R expression. MiR-520a-3p targeted the 3’-UTR of LINC01116 and IL6R. Lower expression levels of miR-520a-3p significantly correlated with shorter survival of patients. LINC01116 and IL6R were up-regulated while miR-520a-3p was down-regulated in OS. LINC01116 and IL6R promoted the viability and migration of OS cells, while miR-520a-3p acted as a tumor suppressor. MiR-520a-3p inhibitor could rescue the suppressive effects of si-LINC011116 and si-IL6R on OS development. The Jak-stat signaling pathway related proteins were also down-regulated by miR-520a-3p. Down-regulation of LINC01116 inhibited the tumor growth in nude mice. Conclusion LINC01116 up-regulated IL6R in OS through targeting miR-520a-3p, thus activating the Jak-stat signaling pathway and promoting the progression of OS.

In the last two decades, quantum dots (QDs) have demonstrated great potential for biophotonics applications such as optical imaging and analytes sensing. For these purposes, cadmium-based (Cd-based) QDs are most commonly used because of their excellent optical properties, while cadmium-free (Cd-free) QDs are attracting increasing attention due to the low toxicity of their components. Generally, for use in biological fluids, QDs are either prepared using the aqueous synthesis method or the hot colloidal synthesis method followed by a phase transfer process. This thesis studies the preparation of water-dispersible Cd-based and Cd-free QD by using these two methods and explores their potential for biophotonics applications. First, this thesis presents a facile aqueous synthesis method for preparing the biofunctionalized Cd-based QDs. The CdTe QD nanocrystals were fabricated in a microfluidic chip by using protein molecules as coordination ligands. Compared to the conventional bench-top method, the microfluidic synthesis approach produced the CdTe QDs with enhanced stability and improved biofunctionalization efficiency. Another method of preparing the aqueous QDs, phase transfer of the QDs synthesized in organic solvents, was also examined. Hydrophilic ligands with different chain lengths and functional groups were applied to render the QDs water-dispersible by using the ligand exchange method. Each set of QDs capped with specific surface ligands displayed strengths and limitations in certain aspects of their physicochemical properties, and induced different cellular responses. To mitigate toxicity concerns in biophotonics applications, Zn-Cu-In-S QDs, which are quaternary and Cd-free QDs, were prepared using a facile aqueous synthesis method. The composition effect on their optical properties is demonstrated and correlated with the evolution of their structure and energy band gap. Using the same strategy of composition control, Zn-Ag-In-S QDs with different emission wavelengths were synthesized in the organic phase and then transferred into the aqueous phase via the encapsulation method. The resulting water-dispersible ZAIS QDs exhibited bright photoluminescence and long fluorescence lifetime and were applied in temporally multiplexed imaging of cells. Finally, ZnO QDs, a type of Cd-free QDs made from wide-band-gap oxides, were prepared using the sol-gel method. Their optical properties were modified via chemical doping and photodoping techniques. Their redox-sensitive photoluminescence and plasmonic properties make them promising candidates for biosensing applications. In summary, this thesis covers the manipulation of optical properties, surface chemistry and biocompatibility of Cd-based and Cd-free QDs using versatile strategies in synthesis and surface modification processes, and demonstrates the potential of using these QDs in biophotonics applications. Doctor of Philosophy (EEE)

Biofunctionalized quantum dots (QDs) are effective target fluorescent labels for bioimaging. However, conventional synthesis of biofunctionalized I-III-VI core-shell CuInS2/ZnS QDs requires complex bench-top operations, resulting in limited product performance and variety, and is not amenable to a 'one-step' approach. In this work, we have successfully demonstrated a fully automated method for preparing denatured bovine serum albumin (dBSA)-CuInS2/ZnS QDs by introducing microfluidic (MF) chips to synthesize biofunctionalized QDs, hence establishing a 'one-step' procedure. We have also studied and optimized the reaction synthesis parameters. The emission wavelength of the dBSA-CuInS2/ZnS QDs is located in the near-infrared range and can be tuned from 650 to 750 nm by simply varying the reaction parameters. In addition, the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs have a long average fluorescence lifetime of 153.76 ns and a small particle size of 5 ± 2 nm. To demonstrate the applicability of the 'one-step'-synthesized dBSA-CuInS2/ZnS QDs in bioimaging studies, we modified the QDs with folic acid and hyaluronic acid, and then performed target bioimaging and cytotoxicity tests on macrophages, liver cancer cells and pancreatic cancer cells. The cell images show that the red emission signals originate from the QDs, which indicates that the dBSA-CuInS2/ZnS QDs prepared by the MF approach are suitable optical contrast agents for target bioimaging. This 'one-step' MF-based QD synthesis approach could serve as a rapid, cost-effective, and small-scale nanocrystal production platform for complex QD formulations for a wide range of bioapplications.

Background Ovarian cancer (OC) is a common female reproductive malignancy with a high mortality rate. Although LAMA4 was observed to be downregulated in OC cells, its mechanism in regulating OC metastasis is still unknown. This study aimed to investigate the effect of LAMA4 and its mechanism on OC. Methods To achieve this aim, a microarray analysis was performed to screen out the key genes involved in OC pathogenesis. Western-blot and qRT-PCR assays were also carried out to detect protein and mRNA expressions, respectively. A luciferase reporter assay was further used to confirm the direct interaction of miR-30e-3p with MEG3, and the direct interaction of miR-30e-3p with LAMA4 mRNA. Cytological experiments (CCK8, colony formation assay, wound-healing assay etc.) were then performed to explore the roles of miR-30e-3p, MEG3, and LAMA4 in OC cells. Results After carrying out microarray analysis, LAMA4 was confirmed as a key gene associated with OC pathogenesis. Research results proved that miR-30e-3p was markedly upregulated, while MEG3 and LAMA4 were noticeably downregulated in OC tissues and cells. The overexpression of LAMA4 significantly impaired the proliferation, migration, and invasion of OC cells. However, the upregulation of MEG3 increased the expression of LAMA4 by sponging miR-30e-3p, which alleviated the malignancy of OC cells. Conclusions Observations showed that forced LAMA4 overexpression could inhibit OC progression, which was regulated by MEG3 via sponging miR-30e-3p. The findings of this research could provide new insights into the mechanism by which MEG3 and LAMA4 exert their anti-oncogenic roles in OC progression. Trial registration Not applicable

We conducted this updated meta-analysis to evaluate the effects of PRP in patients with knee or hip OA.PubMed, Embase, and Web of Science were searched to identify randomized controlled trials (RCTs) that compared the efficacy of PRP with other intra-articular injections. The outcomes of interest included Western Ontario and McMaster (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS), Harris Hip Score (HHS), and International Knee Documentation Committee (IKDC).Twenty-four RCTs with 21 at knee OA and three at hip OA were included in this meta-analysis. The PRP injections significantly improved the WOMAC score, VAS score, IKDC score, and HHS score as compared with comparators. The WOMAC pain, stiffness, and physical function scores were also significantly better in the PRP group than in the control group. Most of the evaluated parameters that favored PRP were observed in knee OA but not in hip OA, at short-term (at 1, 2, 3, 6, 12 months) but not long-term follow-up (at 18 months), in RCTs with low risk of bias.Intra-articular PRP injection provided better effects than other injections for OA patients, especially in knee OA patients, in terms of pain reduction and function improvement at short-term follow-up. Key Points • This updated meta-analysis, based on great sample size and high-quality studies, evaluates the effects of PRP in patients with knee or hip OA. • Intra-articular PRP injection provided better effects than other injections for OA patients. • Most of the evaluated parameters that favored PRP were observed in knee OA at short term (at 1, 2, 3, 6, 12 months).

For semiconductor nanocrystals (NCs), the precise knowledge of phonons in the presence of free carriers is important for understanding their electronic and photonic properties in device applications. With Raman spectroscopy, this study investigates the effects of free charge carriers on optical phonon behaviors of NCs. The adoption of the photocharging method allows us to introduce free charge carriers into NCs without inducing other side effects. In the photocharged ZnO NCs, lower longitudinal optical (LO) phonon frequencies and weaker LO overtones relative to the fundamentals were found, which was explained by the screening and band-filling effects caused by the induced free carriers. The free carrier effects on optical phonon behaviors of NCs, usually neglected in previous studies, should be taken into consideration when discussing the electronic and photonic properties of NC-based devices.

Lectin inspired polymers were prepared through modification of silica microspheres with Ser-Asp (SD). This functional polymer showed distinct adsorption and retention towards different disaccharides and demonstrated high-efficiency enrichment of glycopeptides.

In spite of a considerable breakthrough in antitumor effects of icariin (ICA), the studies regarding other functions of ICA still have not explored widely. This study aimed to report the function of ICA about the growth and migration of benign prostatic hyperplasia epithelial cell line (BPH-1) and human prostate epithelial cell line RWPE-1. Both BPH-1 and RWPE-1 cells were treated with ICA for 12 hr. The cells proliferation, migration, apoptosis were tested by CCK-8 assay, transwell assay, flow cytometry, and western blot. The miR-7 expression was silenced by transfection in both BPH-1 and RWPE-1 cells. The activation of PI3K/AKT and Raf1/ERK1/2 signaling pathways was detected by western blot. ICA inhibited both BPH-1 and RWPE-1 cells proliferation, migration, and promoted apoptosis. Meanwhile, ICA promoted miR-7 expression. Other than this, the changes of cells proliferation inhibition, migration inhibition and apoptosis promotion in both BPH-1 and RWPE-1 cells induced by ICA were reversed partially or completely by transfecting specific miR-7 inhibitor. Apart from this, the activation of PI3K/AKT and Raf1/ERK1/2 signaling pathways was inhibited by ICA through upregulating miR-7 expression. The study released that ICA inhibited both BPH-1 and RWPE-1 cells proliferation, migration and promoted apoptosis by upregulating the levels of miR-7 expression, which was related to PI3K/AKT and Raf1/ERK1/2 signaling pathways.

Small nucleolar RNA host gene 3 (SNHG3) is a long noncoding RNA (lncRNA), which is known to promote oncogenesis in many cancers but its role in human papillary thyroid carcinoma (PTC) remains poorly understood. We therefore assessed SNHG3 expression in PTC tissues via quantitative reverse transcription polymerase chain reaction. We additionally knocked down SNHG3 in PTC cells using short-hairpin RNAs (shRNAs) to explore its functional roles in PTC. The ability of SNHG3 to bind to specific microRNAs (miRNAs) was predicted using a bioinformatics tool, and this binding was confirmed via dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. We then used a tumor xenograft model to assess the relevance of SNHG3 in vivo. We determined SNHG3 expression to be elevated in PTC tissues relative to controls, with advanced tumor-node-metastasis stage and lymph node metastasis being associated with this expression. Knocking down SNHG3 significantly reduced in vitro PTC cell migration, invasion, proliferation, and colony formation, and it further slowed the growth of tumors in vivo. We found that SNHG3 could bind to miR-214-3p as a competing endogenous RNA (ceRNA) for this miRNA, thereby regulating proteasome 26S subunit non-ATPase 10 (PSMD10) expression, a miR-214-3p target. These results thus indicate that SNHG3 is an oncogenic lncRNA in PTC, acting at least in part via the miR-214-3p/PSMD10 axis.

This review summarizes recent progress in the design and applications of cadmium-free quantum dots (Cd-free QDs), with an emphasis on their role in biophotonics and nanomedicine. We first present the features of Cd-free QDs and describe the physics and emergent optical properties of various types of Cd-free QDs whose applications are discussed in subsequent sections. Selected specific QD systems are introduced, followed by the preparation of these Cd-free QDs in a form useful for biological applications, including recent advances in achieving high photoluminescence quantum yield (PL QY) and tunability of emission color. Next, we summarize biophotonic applications of Cd-free QDs in optical imaging, photoacoustic imaging, sensing, optical tracking, and photothermal therapy. Research advances in the use of Cd-free QDs for nanomedicine applications are discussed, including drug/gene delivery, protein/peptide delivery, image-guided surgery, diagnostics, and medical devices. The review then considers the pharmacokinetics and biodistribution of Cd-free QDs and summarizes current studies on the in vitro and in vivo toxicity of Cd-free QDs. Finally, we provide perspectives on the overall current status, challenges, and future directions in this field. MOE (Min. of Education, S’pore) Accepted version

First-line therapy of chronic myelogenous leukemia (CML) has always involved the use of BCR-ABL tyrosine-kinase inhibitors which is associated with an abnormal chromosome called Philadelphia chromosome. Although the overall survival rate has been improved by the current therapeutic regime, the presence of resistance has resulted in limited efficacy. In this study, an RNA interference (RNAi)-based therapeutic regime is proposed with the aim to knockdown the BCR-ABL hybrid oncogene using small interfering RNA (siRNA). The siRNA transfection rates have usually been limited due to the declining contact probability among polyplexes and the non-adherent nature of leukemic cells. Our work aims at addressing this limitation by using a biodegradable charged polyester-based vector (BCPV) as a nanocarrier for the delivery of BCR-ABL-specific siRNA to the suspension culture of a K562 CML cell line. BCR-ABL siRNAs were encapsulated in the BCPVs by electrostatic force. Cell internalization was facilitated by the BCPV and assessed by confocal microscopy and flow cytometry. The regulation of the BCR-ABL level in K562 cells as a result of RNAi was analyzed by real-time polymerase chain reaction (RT-PCR). We observed that BCPV was able to form stable nanoplexes with siRNA molecules, even in the presence of fetal bovine serum (FBS), and successfully assisted in vitro siRNA transfection in the non-adherent K562 cells. As a consequence of downregulation of BCR-ABL, BCPV-siRNA nanoplexes inhibited cell proliferation and promoted cell apoptosis. All results were compared with a commercial transfection reagent, Lipofectamine2000™, which served as a positive control. More importantly, this class of non-viral vector exhibits biodegradable features and negligible cytotoxicity, thus providing a versatile platform to deliver siRNA to non-adherent leukemia cells with high transfection efficiency by effectively overcoming extra- and intra-cellular barriers. Due to the excellent in vitro transfection results from BCPV-siRNA, a newly developed biodegradable transfection agent, BCPV, is being probed for transfection performance in an animal model.

In spite of a considerable breakthrough in antitumor effects of icariin (ICA), the studies regarding other functions of ICA still have not explored widely. This study aimed to report the function of ICA about the growth and migration of benign prostatic hyperplasia epithelial cell line (BPH-1) and human prostate epithelial cell line RWPE-1. Both BPH-1 and RWPE-1 cells were treated with ICA for 12 hr. The cells proliferation, migration, apoptosis were tested by CCK-8 assay, transwell assay, flow cytometry, and western blot. The miR-7 expression was silenced by transfection in both BPH-1 and RWPE-1 cells. The activation of PI3K/AKT and Raf1/ERK1/2 signaling pathways was detected by western blot. ICA inhibited both BPH-1 and RWPE-1 cells proliferation, migration, and promoted apoptosis. Meanwhile, ICA promoted miR-7 expression. Other than this, the changes of cells proliferation inhibition, migration inhibition and apoptosis promotion in both BPH-1 and RWPE-1 cells induced by ICA were reversed partially or completely by transfecting specific miR-7 inhibitor. Apart from this, the activation of PI3K/AKT and Raf1/ERK1/2 signaling pathways was inhibited by ICA through upregulating miR-7 expression. The study released that ICA inhibited both BPH-1 and RWPE-1 cells proliferation, migration and promoted apoptosis by upregulating the levels of miR-7 expression, which was related to PI3K/AKT and Raf1/ERK1/2 signaling pathways.

Intracranial schwannoma accounts for between 5 and 8% of intracranial tumors, whereas intracerebral schwannoma, a rare disease, accounts for 40. The prognosis was classified as good (patient can live independently) for the majority of patients if surgery was able to completely resect the lesion.

Multiternary quantum dots (QDs), because of the large degree of freedom in their structure and composition, have a wide tunability in their bandgap but also exhibit an increased uncertainty and complexity in their optical properties. In this work, we synthesized the ternary Cu-In-S (CIS) and quaternary Zn-Cu-In-S (ZCIS) QDs with different composition ratios via a facile aqueous route. The CIS QDs show multi-peak photoluminescence with their peak intensity dependent on the Cu : In ratio, which was illustrated using a donor-acceptor pair recombination process. Upon incorporation of Zn into the CIS QDs under similar conditions, the acquired ZCIS QDs exhibit blue-shifted photoluminescence (PL) spectra with an enhanced emission intensity and a narrowed spectral width (∼100 nm). A comparative study reveals that, reducing the Cu : In ratio in the CIS QDs and increasing the Zn content in the alloyed ZCIS QDs are both feasible strategies for bandgap engineering, although the influences on optical properties of the QDs were different. The XRD and EDX spectra revealed that the widening of the bandgap of the ZCIS QDs was correlated with the alloyed nanostructures and the preferential substitution of Cu by Zn. Compared to the Cu : In ratio variation, incorporation of Zn into CIS QDs is an effective strategy to achieve a more homogeneous absorption band and a wide range of emission wavelength tunability. After ZnS shell coating, the ZCIS/ZnS QDs show a further enhanced PL intensity with a prolonged fluorescence lifetime. Unlike CIS QDs, the blue shift in PL upon the shell growth was not pronounced for ZCIS QDs, for which a surface reconstruction mechanism was proposed and discussed. Finally, the as-prepared ZCIS/ZnS QDs were employed for in vitro cell imaging and exhibited good biocompatibility to macrophage cells.

Pancreatic cancer is one of the deadliest cancers throughout the world with rarely efficient therapies currently available. Gene therapy on pancreatic cancer through small interfering RNA (siRNA)-based RNA interference (RNAi) has shown great potential and attracted much attention. However, due to the fragile nature of nucleic acid, the application of RNAi as a safe and efficient carrier faces great challenges. In this contribution, a self-assembly regime, which is based on well-defined cationic polylactides (CPLAs) with tertiary amine groups, has been used to encapsulate and protect siRNAs from fast degradation. CPLA is a safe and degradable formulation that allowed us to deliver siRNAs targeting the proangiogenic chemokine interleukin-8 (IL-8) to pancreatic cancer cells for gene therapy. Stable IL-8 siRNA-CPLA nanoplexes were successfully formed by electrostatic force and high gene transfection efficiencies were shown on two pancreatic cancer cell lines. We did not observe any cytotoxicity from these CPLAs over a large concentration range via cell viability evaluations. More importantly, the silencing of IL-8 gene expression significantly attenuated the proliferation of pancreatic cancer cells. Our preliminary results support the future development of gene therapy that might provide an effective and safe treatment approach towards pancreatic cancer.

The toxicity of quantum dots (QDs) has been extensively studied over the past decade. Some common factors that originate the QD toxicity include releasing of heavy metal ions from degraded QDs and the generation of reactive oxygen species on the QD surface. In addition to these factors, we should also carefully examine other potential QD toxicity causes that will play crucial roles in impacting the overall biological system. In this contribution, we have performed cytotoxicity assessment of four types of QD formulations in two different human cancer cell models. The four types of QD formulations, namely, mercaptopropionic acid modified CdSe/CdS/ZnS QDs (CdSe-MPA), PEGylated phospholipid encapsulated CdSe/CdS/ZnS QDs (CdSe-Phos), PEGylated phospholipid encapsulated InP/ZnS QDs (InP-Phos) and Pluronic F127 encapsulated CdTe/ZnS QDs (CdTe-F127), are representatives for the commonly used QD formulations in biomedical applications. Both the core materials and the surface modifications have been taken into consideration as the key factors for the cytotoxicity assessment. Through side-by-side comparison and careful evaluations, we have found that the toxicity of QDs does not solely depend on a single factor in initiating the toxicity in biological system but rather it depends on a combination of elements from the particle formulations. More importantly, our toxicity assessment shows different cytotoxicity trend for all the prepared formulations tested on gastric adenocarcinoma (BGC-823) and neuroblastoma (SH-SY5Y) cell lines. We have further proposed that the cellular uptake of these nanocrystals plays an important role in determining the final faith of the toxicity impact of the formulation. The result here suggests that the toxicity of QDs is rather complex and it cannot be generalized under a few assumptions reported previously. We suggest that one have to evaluate the QD toxicity on a case to case basis and this indicates that standard procedures and comprehensive protocols are urgently needed to be developed and employed for fully assessing and understanding the origins of the toxicity arising from different QD formulations.

InxGa1−xAsyP1−y epilayers have been grown by low-pressure metalorganic vapor phase epitaxy (LPMOVPE) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) as group V precursors and nitrogen as the carrier gas. Arsenic incorporation into InxGa1−xAsyP1−y films grown by LPMOVPE as a function of the gas phase composition ratio and V/III ratio has been systematically studied. With optimized growth conditions, the arsenic composition of the epilayers does not change linearly with the TBA source flow. It is observed that the arsenic incorporation becomes saturated when the gas phase composition TBA/(TBA+TBP) increases to 0.4. The incorporation kinetics in MOVPE growth of InxGa1−xAsyP1−y alloy has been analyzed by using an adsorption-trapping model. The As composition (y) of the InxGa1−xAsyP1−y films varies with the TBA gas phase composition ξ=TBA/(TBA+TBP) according to the expression y=2Ns*/aN0(1−e−θβξ). It is demonstrated that with the optimized growth conditions, TBA has a higher incorporation effic...