Study on Mechanical Properties of Two-Component Polyurethane Based on Multi-Scale Molecular Simulation.

Mechanical properties determine the use of two-component polyurethane materials. The compatibility of two components in the polyether polyol-MDI molecular system greatly influences the formation of mechanical properties in polyurethane materials. In this paper, we studied and evaluated the compatibility and mechanical properties of two-component polyurethane at multiple scales by combining molecular dynamics simulation with macroscopic experiments, which is an important guideline for synthesizing and preparing two-component polyurethanes. We evaluated the stability of the two-component polyurethane system by calculating the solubility parameter, binding energy, and diffusion coefficient at four temperatures with three isocyanate contents. The Perl scripting language obtained the mechanical properties of the MDI-polyether polyol system. The MD calculation results show that the solubility parameter of two-component polyurethane negatively correlated with temperature, and the intermolecular binding energy and MDI diffusion coefficient positively correlated with temperature. When the mass ratio of polyether polyol to isocyanate was 1:0.6, the solubility parameter difference between the two was 1.43 (J/cm3)1/2, the intermolecular binding energy was 531.68 kcal/mol, and the two-component system was more stable. A macroscopic direct tensile test was employed to assess the polyurethane elastomers' tensile properties. Our results show that the tensile strength of polyurethane elastomers increased with the increase in isocyanate content and decrease in temperature. Furthermore, the elongation at the break decreased, and the modulus increased, which is consistent with the law of molecular simulation.

Transfersomes improved delivery of ascorbic palmitate into the viable epidermis for enhanced treatment of melasma.

Ascorbic palmitate (AP) is widely used in the topical pharmaceutical or cosmetic formulations for melasma treatment. However, the presence of the skin barriers makes it difficult for the highly lipophilic drug molecules to traverse the stratum corneum (SC) and diffuse into the viable epidermis (EP) to reach the melanocytes, thereby exerting suboptimal antimelasma effects. Herein, AP was encapsulated into the transfersomes (TFs), yielding AP-TFs. AP-TFs utilized the deformability of TFs to squeeze through the skin pores in the SC under the transepidermal hydration gradient forces, leading to 14.1-fold increase in AP accumulation to the EP. AP-TFs could slowly release the encapsulated AP, while whether the released AP or transfersomal AP showed comparable uptake into the melanocytes, thereby exerting similar inhibitory effects on tyrosinase activity and melanogenesis. Ultimately, in the rat melasma model, AP-TFs showed superior antimelasma efficacy to free AP, with effective relief of oxidative stress and inflammation in the skin. Moreover, AP-TFs did not induce skin irritation. Therefore, the study provides a safe and effective approach to elevating the delivery of highly lipophilic drugs to the EP for enhanced treatment of melasma.

Rose Bengal-Amphiphilic Peptide Conjugate for Enhanced Photodynamic Therapy of Malignant Melanoma.

Malignant melanoma is an aggressive skin cancer with poor survival outcomes for patients diagnosed at an advanced stage. While targeted serine/threonine-protein kinase B-Raf (BRAF) and immune checkpoint inhibitors have improved survival outcomes for a proportion of these patients, response rates remain variable. There is a need, therefore, for more effective treatments to bolster the options available for melanoma patients. In this manuscript, we covalently attached Rose Bengal (RB) to the amphipathic peptide (AMP) C(KLAKLAK)2 and determined the effectiveness of the resulting RB-C(KLAKLAK)2 conjugate as a photodynamic therapy (PDT) sensitizer. RB-C(KLAKLAK)2-mediated PDT treatment of subcutaneous B16-F10-Luc2 tumors in C57 mice resulted in lesions that were 479% smaller at the end of the study than animals treated with RB-mediated PDT. The synergistic effect between RB and C(KLAKLAK)2 has been attributed to the AMP sensitizing cells to reactive oxygen species (ROS), making them more susceptible to ROS-induced oxidative stress.

Magnetic microbubble mediated chemo-sonodynamic therapy using a combined magnetic-acoustic device.

Recent pre-clinical studies have demonstrated the potential of combining chemotherapy and sonodynamic therapy for the treatment of pancreatic cancer. Oxygen-loaded magnetic microbubbles have been explored as a targeted delivery vehicle for this application. Despite preliminary positive results, a previous study identified a significant practical challenge regarding the co-alignment of the magnetic and ultrasound fields. The aim of this study was to determine whether this challenge could be addressed through the use of a magnetic-acoustic device (MAD) combining a magnetic array and ultrasound transducer in a single unit, to simultaneously concentrate and activate the microbubbles at the target site. in vitro experiments were performed in tissue phantoms and followed by in vivo treatment of xenograft pancreatic cancer (BxPC-3) tumours in a murine model. In vitro, a 1.4-fold (p < .01) increase in the deposition of a model therapeutic payload within the phantom was achieved using the MAD compared to separate magnetic and ultrasound devices. In vivo, tumours treated with the MAD had a 9% smaller mean volume 8 days after treatment, while tumours treated with separate devices or microbubbles alone were respectively 45% and 112% larger. This substantial and sustained decrease in tumour volume suggests that the proposed drug delivery approach has the potential to be an effective neoadjuvant therapy for pancreatic cancer patients.

Targeted chemo-sonodynamic therapy treatment of breast tumours using ultrasound responsive microbubbles loaded with paclitaxel, doxorubicin and Rose Bengal.

Mastectomy is a common surgical treatment used in the management of breast cancer but has associated physical and psychological consequences for the patient. Breast conservation surgery (BCS) is an alternative to mastectomy but is only possible when the tumour is of an appropriate size. Neo-adjuvant chemotherapy has been successfully used to downstage tumours and increase the number of patients eligible for BCS. However, the chemotherapies used in this approach are non-targeted and often result in significant side effects to the patient. In this manuscript, we evaluate the potential of ultrasound targeted microbubble destruction (UTMD) to deliver Rose Bengal-mediated sonodynamic therapy (SDT) in combination with paclitaxel (PTX) and doxorubicin (Dox) chemotherapy as a potential treatment for breast cancer. Efficacy of the combined treatment was determined in a three-dimensional (3D) spheroid model of human breast cancer and in a murine model of the disease bearing subcutaneous MCF-7 tumours. The results demonstrated a significant reduction in both the cell viability of spheroids and tumour volume following treatment with the drug loaded microbubbles and ultrasound compared to targets treated with the drug loaded microbubbles alone or a Cremophor EL suspension of PTX and Dox. In addition, the weight of animals that received the microbubble treatment was unchanged throughout the study while a reduction of 12.1% was observed for animals treated with a Cremophor suspension of PTX/Dox. These results suggest that UTMD-mediated chemo-sonodynamic therapy is an efficacious and well tolerated approach for the treatment of breast cancer.

Electroneutral polymersomes for combined cancer chemotherapy.

Combination cancer chemotherapy provides an important treatment tool, both as an adjuvant and neoadjuvant treatment, this shift in focus from mono to combination therapies has led to increased interest in drug delivery systems (DDS). DDSs, such as polymersomes, are capable of encapsulating large amounts of multiple drugs with both hydrophilic and hydrophobic properties simultaneously, as well as offering a mechanism to combat multi drug resistant cancers and poor patient tolerance of the cytotoxic compounds utilised. In this article, we report the formulation and evaluation of a novel electroneutral polymersome capable of high encapsulation efficacies for multiple drugs (Doxorubicin, 5-Fluorouracil and leucovorin). The in-vivo biodistribution of the polymersome were established and they were found to accumulate largely in tumour tissue. Polymersome encapsulating the three chemotherapeutic drugs were assessed both in-vitro (BxPC-3 cell line) and in-vivo (following intratumoral and intravenous administration) and compared with the same concentration of the three drugs in solution. We report better efficacy and higher maximum tolerated dose for our combination drug loaded polymersomes in all experiments. Furthermore, intratumorally injected combination drug loaded polymersomes exhibited a 62% reduction in tumour volume after 13 days when compared with the free combination solutions. A smaller differential of 13% was observed for when treatment was administered intravenously however, importantly less cardiotoxicity was displayed from the polymersomal DDS. In this study, expression of a number of survival-relevant genes in tumours treated with the free chemotherapy combination was compared with expression of those genes in tumours treated with the polymersomes harbouring those drugs and the significance of findings is discussed. STATEMENT OF SIGNIFICANCE: The shift in focus from mono to combination chemotherapies has led to an increased interest in the role of drug delivery systems (DDS). Liposomes, although commercialized for mono therapy, have lower loading capacities and stability than their polymeric counterpart, polymersomes. Polymersomes are growing in prevalence as their advantageous properties are better understood and exploited. Here we present a novel polymersome for the encapsulation of three anticancer compounds. This is the first time this particular polymersome has been used to encapsulate these three compounds with both an in-vitro and in-vivo evaluation carried out. This work will be of interest to those in the field of combination therapy, drug delivery, drug toxicity, multidrug resistance, liposomes, DDS and polymersomes.

Rapid paper based colorimetric detection of glucose using a hollow microneedle device.

The monitoring of blood glucose is a key aspect of diabetes care in limiting the negative effects of hyperglycaemia to both the microvasculature and macrovasculature. Self-monitoring of blood glucose (SMBG) gives an indication of blood glucose at a specific point in time and is recommended to be carried out four times daily. However, due to the inconvenience and associated pain of blood withdrawal, SMBG is often carried out less frequently than recommended or not at all. Extraction and subsequent determination of glucose in interstitial fluid (ISF) using microneedles (MNs) is an emerging area of research due to their minimally invasive nature and lack of associated pain. In this manuscript, a novel method for the fabrication of a hollow microneedle device is reported. The microneedle produced had a sharp bevelled edge and was 400 µm in length. Additionally, a paper backplate embedded with a colorimetric system for the rapid visual determination of glucose in simulated ISF was developed and paired with the hollow MN. This device rapidly extracted simulated ISF within five seconds and its ability to produce a glucose concentration dependent colour change within 30 s was demonstrated. Using this approach, it was possible to discriminate between glucose concentrations in normal glycaemia (4-7 mM) and hyperglycaemia (>7 mM) ranges using the naked eye. While further development is required, the results herein highlight the potential of this device to be used as a blood-free minimally invasive approach to glucose monitoring.

Gemcitabine loaded microbubbles for targeted chemo-sonodynamic therapy of pancreatic cancer.

Pancreatic cancer remains one of the most lethal forms of cancer with a 10-year survival of <1%. With little improvement in survival rates observed in the past 40 years, there is a significant need for new treatments or more effective strategies to deliver existing treatments. The antimetabolite gemcitabine (Gem) is the most widely used form of chemotherapy for pancreatic cancer treatment, but is known to produce significant side effects when administered systemically. We have previously demonstrated the benefit of combined chemo-sonodynamic therapy (SDT), delivered using oxygen carrying microbubbles (O2MB), as a targeted treatment for pancreatic cancer in a murine model of the disease. In this manuscript, we report the preparation of a biotin functionalised Gem ligand for attachment to O2MBs (O2MB-Gem). We demonstrate the effectiveness of chemo-sonodynamic therapy following ultrasound-targeted-microbubble-destruction (UTMD) of the O2MB-Gem and a Rose Bengal loaded O2MB (O2MB-RB) as a targeted treatment for pancreatic cancer. Specifically, UTMD using the O2MB-Gem and O2MB-RB conjugates reduced the viability of MIA PaCa-2, PANC-1, BxPC3 and T110299 pancreatic cancer cells by >60% (p < 0.001) and provided significant tumour growth delay (>80%, p < 0.001) compared to untreated animals when human xenograft MIA PaCa-2 tumours were treated in SCID mice. The toxicity of the O2MB-Gem conjugate was also determined in healthy non-tumour bearing MF1 mice and revealed no evidence of renal or hepatic damage. Therefore, the results presented in this manuscript suggest that chemo-sonodynamic therapy using the O2MB-Gem and O2MB-RB conjugates, is potentially an effective targeted and safe treatment modality for pancreatic cancer.

Oxygen generating nanoparticles for improved photodynamic therapy of hypoxic tumours.

Photodynamic therapy (PDT) is a clinically approved anti-cancer treatment that involves the activation of an otherwise inactive sensitiser drug with light, which in the presence of molecular oxygen, generates cytotoxic reactive oxygen species (ROS). As oxygen is a key requirement for the generation of ROS in PDT and given the fact that hypoxia is a characteristic of most solid cancerous tumours, treating hypoxic tumours using PDT can be a challenge. In this manuscript, we have prepared a CaO2 nanoparticle (NP) formulation coated with a pH-sensitive polymer to enable the controlled generation of molecular oxygen as a function of pH. The polymer coat was designed to protect the particles from decomposition while in circulation but enable their activation at lower pH values in hypoxic regions of solid tumours. The oxygen generating capability of the polymer coated NPs was demonstrated in aqueous solution with minimal oxygen produced at pH7.4, whereas it increased significantly when the pH was reduced to 6.2. The polymer coated CaO2 NPs were also observed to significantly increase tumour pO2 levels (p<0.05) in mice bearing ectopic human xenograft MIA PaCa-2 pancreatic tumours with an average increase in tumour pO2 of 6.5mmHg in the period 10-30min following administration. A statistically significant improvement in PDT mediated efficacy (p<0.001) was also observed when the particles were administered to mice bearing the same tumours 20min prior to PDT treatment. These results suggest that the polymer coated CaO2 NP formulation offers significant potential as an in situ method for oxygen generation to enhance the efficacy of treatments that depend on the presence of oxygen to elicit a cytotoxic effect.

Magnetically responsive microbubbles as delivery vehicles for targeted sonodynamic and antimetabolite therapy of pancreatic cancer.

Magnetically responsive microbubbles (MagMBs), consisting of an oxygen gas core and a phospholipid coating functionalised with Rose Bengal (RB) and/or 5-fluorouracil (5-FU), were assessed as a delivery vehicle for the targeted treatment of pancreatic cancer using combined antimetabolite and sonodynamic therapy (SDT). MagMBs delivering the combined 5-FU/SDT treatment produced a reduction in cell viability of over 50% when tested against a panel of four pancreatic cancer cell lines in vitro. Intravenous administration of the MagMBs to mice bearing orthotopic human xenograft BxPC-3 tumours yielded a 48.3% reduction in tumour volume relative to an untreated control group (p<0.05) when the tumour was exposed to both external magnetic and ultrasound fields during administration of the MagMBs. In contrast, application of an external ultrasound field alone resulted in a 27% reduction in tumour volume. In addition, activated caspase and BAX protein levels were both observed to be significantly elevated in tumours harvested from animals treated with the MagMBs in the presence of magnetic and ultrasonic fields when compared to expression of those proteins in tumours from either the control or ultrasound field only groups (p<0.05). These results suggest MagMBs have considerable potential as a platform to enable the targeted delivery of combined sonodynamic/antimetabolite therapy in pancreatic cancer.

[Determination of trace iodide in drinking water in Shanghai by two columns and gas chromatography with electron capture detection].

OBJECTIVE: To modify and optimize gas chromatographic conditions, qualitative and quantitative method on the base of the actual national standard detection method for drinking water on testing iodide with gas chromatography, and detect iodide in drinking water of Shanghai. METHODS: Iodobutane derivative was identified by gas chromatography/mass spectrometry, then two capillary columns coupled to electron capture detector were made by qualitative and quantitative analysis. Finally, 100 ml water samples were collected respectively from raw water and finished water of three plants in which water sources were Yangtse river, Huangpu river, and inner river respectively and detected by this developed method. RESULTS: The results of mass spectrometry showed that iodide would form iodobutane which could generate 1-iodo-2-butanone and 3-iodo-2-butanone isomers by derivatization. The data of qualitative analysis by two capillary columns revealed that iodobutane was separated completely and the total time of chromatogram separation was 19.33 min.3-iodo-2-butanone with the high response value was selected to quantitatively analyse. The linear range was 1 - 100 µg/L, and the coefficient of determination (r(2)) was 0.9997. The limit of detection was 13 ng/L. Recoveries were between 97.68% and 104.37%, and relative standard deviations were between 2.14% and 4.41%. The results of iodide detected by this method in raw water and finished water in three plants in Shanghai showed that the ranking of iodide's concentration in raw water was Huangpu river (15.14 µg/L) > inner river (6.97 µg/L) > Yangtse river (3.55 µg/L). The level of iodide in finished water of plant 1 (3.55 µg/L and 5.92 µg/L for raw and finished water respectively) and 3 (6.97 µg/L and 9.62 µg/L for raw and finished water respectively) increased slightly except for plant 2 (15.14 µg/L and 1.81 µg/L for raw and finished water respectively). The relative standard deviations of all water samples measured in duplicate were less than 9.73%. CONCLUSION: The improved method possesses higher degree of sensitivity and accuracy of qualitative and quantitative analysis than actual national standard detection method, and it is fit for trace analysis of iodide in water.