A new three-component formulation for the efficient whitening of teeth (Carbamide Plus).

OBJECTIVES: This study aimed to develop and characterise a new three-component dental whitening formulation which is as effective as the currently used carbamide peroxide but at significantly lower hydrogen peroxide concentrations. MATERIALS AND METHODS: The new formulation (Carbamide Plus) was prepared containing hydrogen peroxide, urea, and sodium tripolyphosphate and compared directly with carbamide peroxide (containing just hydrogen peroxide and urea). To evaluate the clinical effectiveness of 5% Carbamide Plus, a randomised double-blind placebo-controlled clinical trial was conducted comparing the tooth colour of 33 patients using L*a*b* scores at baseline and after a 2-week whitening treatment. The behaviour of the three components in solution was determined by (1)H and (31)P NMR spectroscopy and pH dilution experiments. RESULTS: This clinical trial revealed that 5% whitening gels containing Carbamide Plus were as effective as those containing 10% carbamide peroxide. (1)H and (31)P NMR spectroscopy revealed strong intermolecular interactions between hydrogen peroxide and both urea and sodium tripolyphosphate (STPP) with little apparent interaction between urea and STPP. CONCLUSIONS: In this manuscript, we postulate that this increased whitening efficiency is due to a marked increase in local pH upon dilution which destabilises the hydrogen peroxide and expedites the whitening process. We postulate Carbamide Plus to be a three-component adduct with two molecules of carbamide peroxide binding to a central STPP unit with no direct interaction between STPP and urea. There were no statistically significant differences between Carbamide Plus and 10% carbamide peroxide in tooth-whitening achieved at 2 weeks. These results were recorded following 2 weeks of 2-h daily wear of at-home trays. CLINICAL RELEVANCE: Carbamide Plus offers the potential of using significantly lower levels of hydrogen peroxide concentration to achieve similar dental whitening effects.

Intracellular guest exchange between dynamic supramolecular hosts.

Decyl and oligo(ethylene glycol) chains were appended to the same poly(methacrylate) backbone to generate an amphiphilic polymer with a ratio between hydrophobic and hydrophilic segments of 2.5. At concentrations greater than 10 µg mL(-1) in neutral buffer, multiple copies of this particular macromolecule assemble into nanoparticles with a hydrodynamic diameter of 15 nm. In the process of assembling, these nanoparticles can capture anthracene donors and borondipyrromethene acceptors within their hydrophobic interior and permit the transfer of excitation energy with an efficiency of 95%. Energy transfer is observed also if nanocarriers containing exclusively the donors are mixed with nanoparticles preloaded separately with the acceptors in aqueous media. The two sets of supramolecular assemblies exchange their guests with fast kinetics upon mixing to co-localize complementary chromophores within the same nanostructured container and enable energy transfer. After guest exchange, the nanoparticles can cross the membrane of cervical cancer cells and bring the co-entrapped donors and acceptors within the intracellular environment. Alternatively, intracellular energy transfer is also established after sequential cell incubation with nanoparticles containing the donors first and then with nanocarriers preloaded with the acceptors or vice versa. Under these conditions, the nanoparticles exchange their cargo only after internalization and allow energy transfer exclusively within the cell interior. Thus, the dynamic character of such supramolecular containers offers the opportunity to transport independently complementary species inside cells and permit their interaction only within the intracellular space.

Supramolecular strategies to construct biocompatible and photoswitchable fluorescent assemblies.

We designed and synthesized an amphiphilic copolymer with pendant hydrophobic decyl and hydrophilic poly(ethylene glycol) chains along a common poly(methacrylate) backbone. This macromolecular construct captures hydrophobic boron dipyrromethene fluorophores and hydrophobic spiropyran photochromes and transfers mixtures of both components in aqueous environments. Within the resulting hydrophilic supramolecular assemblies, the spiropyran components retain their photochemical properties and switch reversibly to the corresponding merocyanine isomers upon ultraviolet illumination. Their photoinduced transformations activate intermolecular electron and energy transfer pathways, which culminate in the quenching of the boron dipyrromethene fluorescence. As a result, the emission intensity of these supramolecular constructs can be modulated in aqueous environments under optical control. Furthermore, the macromolecular envelope around the fluorescent and photochromic components can cross the membrane of Chinese hamster ovarian cells and transport its cargo unaffected into the cytosol. Indeed, the fluorescence of these supramolecular constructs can be modulated also intracellularly by operating the photochromic component with optical inputs. In addition, cytotoxicity tests demonstrate that these supramolecular assemblies and the illumination conditions required for their operation have essentially no influence on cell viability. Thus, supramolecular events can be invoked to construct fluorescent and photoswitchable systems from separate components, while imposing aqueous solubility and biocompatibility on the resulting assemblies. In principle, this simple protocol can evolve into a general strategy to deliver and operate intracellularly functional molecular components under optical control.

An ultrasound responsive microbubble-liposome conjugate for targeted irinotecan-oxaliplatin treatment of pancreatic cancer.

Survival rates in pancreatic cancer have remained largely unchanged over the past four decades with less than 5% of patients surviving five years following initial diagnosis. FOLFIRINOX chemotherapy, a combination of folinic acid, 5-fluoruracil, irinotecan and oxaliplatin, has shown the greatest survival benefit for patients with advanced disease but is only indicated for those with good physical performance status due to its extreme off-target toxicity. Ultrasound targeted microbubble destruction (UTMD) has emerged as an effective strategy for the targeted delivery of drug payloads to solid tumours and involves using low intensity ultrasound to disrupt (burst) MBs in the tumour vasculature, releasing encapsulated or attached drugs in a targeted manner. In this manuscript, we describe the preparation of a microbubble-liposome complex (IRMB-OxLipo) carrying two of the three cytotoxic drugs present in the FOLFIRINOX combination, namely irinotecan and oxaliplatin. Efficacy of the IRMB-OxLipo complex following UTMD was determined in Panc-01 3D spheroid and BxPC-3 human xenograft murine models of pancreatic cancer. The results revealed that tumours treated with the IRMB-OxLipo complex and ultrasound were 136% smaller than tumours treated with the same concentration of irinotecan/oxaliplatin but delivered in a conventional manner, i.e. as a non-complexed mixture. This suggests that UTMD facilitates a more effective delivery of irinotecan/oxaliplatin improving the overall effectiveness of this drug combination and to the best of our knowledge, is the first reported example of a microbubble-liposome complex used to deliver these two chemotherapies.

Phthalocyanine-loaded nanostructured lipid carriers functionalized with folic acid for photodynamic therapy.

Breast cancer is a serious public health problem that causes thousands of deaths annually. Chemotherapy continues to play a central role in the management of breast cancer but is associated with extreme off-target toxicity. Therefore, treatments that directly target the tumor and display reduced susceptibility to resistance could improve the outcome and quality of life for patients suffering from this disease. Photodynamic therapy is a targeted treatment based on the use of light to activate a photosensitizer (PS) that then interacts with molecular oxygen and other biochemical substrates to generate cytotoxic levels of Reactive Oxygen Species. Currently approved PS also tends to have poor aqueous solubility that can cause problems when delivered intravenously. In order to circumvent this limitation, in this manuscript, we evaluate the potential of a phthalocyanine-loaded nanostructured lipid carrier (NLC) functionalized with folic acid (FA). To prepare the FA labelled NLC, the polymer PF127 was first esterified with FA and emulsified with an oil phase containing polyoxyethylene 40 stearate, capric/caprylic acid triglycerides, ethoxylated hydrogenated castor oil 40 and the PS zinc phthalocyanine. The resulting PS loaded FA-NLC had a hydrodynamic diameter of 180 nm and were stable in suspension for >90 days. Interestingly, the amount of singlet oxygen generated upon light activation for the PS loaded FA-NLC was substantially higher than the free PS, yet at a lower PS concentration. The PS was released from the NLC in a sustained manner with 4.13 ±â€¯0.58% and 27.7 ±â€¯3.16% after 30 min and 7 days, respectively. Finally, cytotoxicity assays showed that NLC in the concentrations of 09.1 µM of PS present non-toxic with >80 ±â€¯6.8% viable and after 90 s of the light-exposed the results show a statistically significant decrease in cell viability (57 ±â€¯4%). The results obtained allow us to conclude that the functionalized NLC incorporated with PS associated with the PDT technique have characteristics that make them potential candidates for the alternative 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.

Recent advances in amphiphilic polymers for simultaneous delivery of hydrophobic and hydrophilic drugs.

Nanomedicine has evolved with the use of biological compounds such as proteins, peptides and DNA. These hydrophilic and often highly charged compounds require a delivery system to allow effective transport and release at the site of action. These new biological therapeutics have not replaced the more traditional smaller molecule, but instead are working synergistically to the benefit of the end user. To that end, drug delivery systems are now required to encapsulate both larger hydrophilic compounds as well as the smaller and generally more hydrophobic compound. This review highlights the emerging role in drug delivery of amphiphilic polymers that by their very nature can associate with compounds of differing physicochemical properties, in particular the role of micelles, polymersomes and nanocapsules.

Cholesteryl to improve the cellular uptake of polymersomes within HeLa cells.

The need to develop a greater understanding of drug delivery systems has arisen through the development of alternative biological based therapeutics. Drug delivery systems need to adapt and respond to this increasing demand for cellular transportation of highly charged species. Polymersomal drug delivery systems have displayed great potential and versatility for such a task. In this manuscript we present the synthesis, characterisation and biological evaluation of six amphiphilic random co polymers with varying amounts of cholesteryl (0-39%wt) before the subsequent formation into polymersomes. The polymersomes were then analysed for size, zeta potential, encapsulation efficiency, release kinetics and cellular uptake. Results confirmed that the polymersome containing 12%wt cholesteryl polymer displayed a ten-fold increase in cellular uptake of Fitc-CM-dextran when compared to un-encapsulated drug, crossing the cellular membrane via endocytosis. The size of these vehicles ranged between 100 and 500nm, zeta potential was shown to be neutral at -0.82mV ±0.2 with encapsulation efficiencies in the region of 60%. The ease of adaptability and preparation of such systems renders them a viable alternative to liposomal drug delivery systems.

A charge neutral, size tuneable polymersome capable of high biological encapsulation efficiency and cell permeation.

The field of therapeutics is evolving to include a greater proportion of higher molecular weight, hydrophilic biological compounds. To cater for this new era in healthcare the concomitant development of appropriate drug delivery systems is essential to aid cellular permeation. In this manuscript we present the synthesis, characterisation and biological evaluation of a charge neutral polymersome (Ps) based drug delivery system (DDS) using an amphiphilic pegylated random copolymer. A detailed dynamic light scattering study revealed that the hydrodynamic diameter of the Ps can be tailored to a specific size simply by varying the quantities and ratios used during the preparation step. The zeta potential of this new drug delivery system was determined to be -0.095 ± 0.037 mV, the encapsulation efficiency of Fitc-CM-Dextran (4 KDa) was 70%, the uptake of Fitc-CM-Dextran by Hela cells was increased 4-fold when encapsulated within the polymersomal system. The facile preparation, high loading capacity and size tuneable nature of this Ps renders it a promising alternative to the ever growing array of currently available Ps.

Supramolecular nanoreactors for intracellular singlet-oxygen sensitization.

An amphiphilic polymer with multiple decyl and oligo(ethylene glycol) chains attached to a common poly(methacrylate) backbone assembles into nanoscaled particles in aqueous environments. Hydrophobic anthracene and borondipyrromethene (BODIPY) chromophores can be co-encapsulated within the self-assembling nanoparticles and transported across hydrophilic media. The reversible character of the noncovalent bonds, holding the supramolecular containers together, permits the exchange of their components with fast kinetics in aqueous solution. Incubation of cervical cancer (HeLA) cells with a mixture of two sets of nanoparticles, pre-loaded independently with anthracene or BODIPY chromophores, results in guest scrambling first and then transport of co-entrapped species to the intracellular space. Alternatively, incubation of cells with the two sets of nanocarriers in consecutive steps permits the sequential transport of the anthracene and BODIPY chromophores across the plasma membrane and only then allows their co-encapsulation within the same supramolecular containers. Both mechanisms position the two sets of chromophores with complementary spectral overlap in close proximity to enable the efficient transfer of energy intracellularly from the anthracene donors to the BODIPY acceptors. In the presence of iodine substituents on the BODIPY platform, intersystem crossing follows energy transfer. The resulting triplet state can transfer energy further to molecular oxygen with the concomitant production of singlet oxygen to induce cell mortality. Furthermore, the donor can be excited with two near-infrared photons simultaneously to permit the photoinduced generation of singlet oxygen intracellularly under illumination conditions compatible with applications in vivo. Thus, these supramolecular strategies to control the excitation dynamics of multichromophoric assemblies in the intracellular environment can evolve into valuable protocols for photodynamic therapy.

Highly luminescent biocompatible Carbon Quantum Dots by encapsulation with an amphiphilic polymer.

Highly luminescent, water-soluble and biocompatible Carbon Quantum Dots (aqCQDs) were prepared by encapsulating the parent hydrophobic CQDs in an amphiphilic polymer. The resulting aqCQDs were non-toxic to living cells, and were found to cross the cell membrane and localise primarily in the cytosol.

Biocompatible CdSe-ZnS core-shell quantum dots coated with hydrophilic polythiols.

We designed four polymeric ligands for semiconductor quantum dots and synthesized these macromolecular constructs in four steps, starting from commercial precursors. These ligands have a poly(methacrylate) backbone with pendant thiol groups and poly(ethylene glycol) chains. The thiol groups anchor these ligands on the surface of preformed CdSe-ZnS core-shell quantum dots, and the poly(ethylene glycol) chains impose hydrophilic character on the resulting assemblies. Indeed, three of the four sets of quantum dots are soluble in aqueous environments and are stable under these conditions for days over a wide pH range (5.0-9.0). Furthermore, the polymeric coatings wrapped around the inorganic nanoparticles preserve the photophysical properties of the CdSe core and ensure relatively compact dimensions. Specifically, the luminescence quantum yield is ca. 0.4 and the hydrodynamic diameter ranges from 15 to 29 nm with the nature of the polymeric ligand. Model studies with human umbilical vein endothelial cells demonstrated that these hydrophilic quantum dots cross the cell membrane and localize either in the cytosol or in the nucleus. The length of the poly(ethylene glycol) chains appears to guide the intracellular localization of these luminescent probes. In addition, these studies indicated that these particular nanoparticles are not cytotoxic. In fact, their cellular internalization has essentially no influence on cell growth. In summary, we developed novel polymeric ligands able to impose hydrophilic character and biocompatibility on CdSe-ZnS core-shell nanoparticles. Thus, our results can lead to a new family of valuable luminescent probes for cellular imaging, based on the unique photophysical properties of semiconductor quantum dots.