Characterization of Ion-Exchange Fibers for Controlled Drug Delivery

Increasing attention has been focused on methods that deliver pharmacologically active compounds (e.g. drugs, peptides and proteins) in a controlled fashion, so that constant, sustained, site-specific or pulsatile action can be attained. Ion-exchange resins have been widely studied in medical and pharmaceutical applications, including controlled drug delivery, leading to commercialisation of some resin based formulations. Ion-exchangers provide an efficient means to adjust and control drug delivery, as the electrostatic interactions enable precise control of the ion-exchange process and, thus, a more uniform and accurate control of drug release compared to systems that are based only on physical interactions. Unlike the resins, only few studies have been reported on ion-exchange fibers in drug delivery. However, the ion-exchange fibers have many advantageous properties compared to the conventional ion-exchange resins, such as more efficient compound loading into and release from the ion-exchanger, easier incorporation of drug-sized compounds, enhanced control of the ion-exchange process, better mechanical, chemical and thermal stability, and good formulation properties, which make the fibers attractive materials for controlled drug delivery systems. In this study, the factors affecting the nature and strength of the binding/loading of drug-sized model compounds into the ion-exchange fibers was evaluated comprehensively and, moreover, the controllability of subsequent drug release/delivery from the fibers was assessed by modifying the conditions of external solutions. Also the feasibility of ion-exchange fibers for simultaneous delivery of two drugs in combination was studied by dual loading. Donnan theory and theoretical modelling were applied to gain mechanistic understanding on these factors. The experimental results imply that incorporation of model compounds into the ion-exchange fibers was attained mainly as a result of ionic bonding, with additional contribution of non-specific interactions. Increasing the ion-exchange capacity of the fiber or decreasing the valence of loaded compounds increased the molar loading, while more efficient release of the compounds was observed consistently at conditions where the valence or concentration of the extracting counter-ion was increased. Donnan theory was capable of fully interpreting the ion-exchange equilibria and the theoretical modelling supported precisely the experimental observations. The physico-chemical characteristics (lipophilicity, hydrogen bonding ability) of the model compounds and the framework of the fibrous ion-exchanger influenced the affinity of the drugs towards the fibers and may, thus, affect both drug loading and release. It was concluded that precisely controlled drug delivery may be tailored for each compound, in particularly, by choosing a suitable ion-exchange fiber and optimizing the delivery system to take into account the external conditions, also when delivering two drugs simultaneously.

Olen maa johon tahdot : Timo K. Mukan maailmankuvan poetiikkaa

The dissertation deals with the prose texts of the Finnish writer Timo K. Mukka, renowned for his depictions of his native Lapland. This research concerns the creation of world view in Mukka s prose, which is approached by studying what Mikhail Bakhtin calls generic change. Such genre change is the most characteristic feature of Mukka s prose. His prose is permeated with two genres in particular and changes between them: the ballad-like, archaistic and romantic prose-poem style and naturalistic, even grotesque expressions. In addition, these genres are associated with sublime and grotesque styles so that generic change tends to involve also stylistic changes in Mukka s prose. This study probes the tension-filled interrelationships between the ballad and naturalistic prose by examining the discourse of Mukka s characters. It is shown that these characters invariably find themselves in what Bakhtin calls the chronotope of the threshold; that is, the plots of Mukka s novels and short stories depict situations in which the characters are faced with decisions and deeds that will profoundly impact their lives. The discourse of the threshold affects the characters speech by filling it with dialogical dimensions. This makes their communication ethically loaded and polyphonic. This study is based on Mikhail Bakhtin s theory of the novel and international Bakhtin s studies. I also take into consideration the theoretical developments of Bakhtin s work; for example, the concept of ressentiment, adapted from the Bakhtin scholar Michel André Bernstein, plays an important role. In order to explicate on the psychology of Mukka s characters such as melancholy, abjection, sadism, and taboo I use the concepts familiar from Freudian psychoanalysis. The corpus of my research consists of the following texts: the long prose texts Maa on syntinen laulu. Balladi (1964), Tabu (1965), Täältä jostakin. Romaani (1965), Laulu Sipirjan lapsista. Romaani (1966), Ja kesän heinä kuolee. Kertomus sairaudesta (1968) ja Kyyhky ja unikko (1970) and the short story collections Koiran kuolema (1967) ja Lumen pelko (1970), and with Tabu published short story Sankarihymni , the short story Katkelma laajemmasta laulelmasta from the collection Rakastaa: Kaksitoista novellia rakkaudesta (1965) and also the short stories which were published in various Finnish journals: Yöt (1965), Liisa (1967), Tyttö (1967) ja Näin hetki sitten ketun (1970). I pay particular attention to the novel Maa on syntinen laulu, because it expresses the generic change characteristic of Mukka s world view in a specifically clear and lively way. The dissertation is in Finnish. Key words: Timo K. Mukka, world view, genre change, ballad, naturalism, grotesque realism, Mikhail Bakhtin, dialogism, polyphony, chronotope, sublime, grotesque, ressentiment, Sigmund Freud, melancholy, taboo, abject, sadism, reduced laughter, modern parody.

Noviisiopettajana peruskoulussa : Aloittelevien opettajien autenttisia kokemuksia ensimmäisestä opettajavuodesta

As a Novice Teacher at Comprehensive School: The authentic experiences of the beginning teachers during their first year of teaching The aim of this study is to explicate the novice year of teaching in the light of teachers´ authentic experiences. The subject of this investigation is the teachers´ subjective world of experience during their first academic year of teaching and the sharing of these experiences in collaborative consulting meetings. The themes discussed in the meetings were introduced into the collaborative group by the novice teachers themselves, and the progress of discussion was con-trolled by them. The research data was gathered in a consultative working group where the way a novice teacher starts to interpret, analyze and identify his/her own complex and dynamic teaching situations was observed. The research data gathered in this way illuminates novice teachers´ world of experience and mental picture as well as the unconscious sides of school life. In a theoretical frame of reference, the work of a teacher is identified, according to systemic scientific thought, as a dynamic triangle in which the basic elements are the personality of the teacher, the role of the teacher and the school as an organization. These basic elements form a whole within which the teacher works. The dynamics of this triangle in a teacher’s work are brought to light through the study of the phenomena of groups and group dynamics since a teacher works either as a member of a group (working community), as a leader of a group (teaching situations) or in a network (parent – teacher cooperation). Therefore, tension and force are always present in teaching work. The main research problem was to explain how a novice teacher experiences his/her first working year as a teacher. The participants (n=5) were teaching at five different comprehensive schools in the city of Helsinki. This was their first long-term post as a teacher. The research data consists of seven collaborative consulting meetings, as well as recordings and transcripts of the meetings. A classificatory framework was developed for data analysis which enabled a sys-tematic qualitative content analysis based on theory and material. In addition to the consulting meetings, the teachers were interviewed at the beginning and at the end of the process of collecting the research material. The interviews were used to interpret the meanings of the content analysis based on raw data. The findings show that there is a gap between teacher education and the reality of school life, which causes difficulties for a novice teacher during his/her first teaching year. The gap is rather a global educational problem than a national one, and therefore it is independent of cultural factors. Novice teachers desire a well-structured theory of teacher education and a clear programme where the themes and content delve deeper and deeper into the subject matter during the study years. According to the novice teachers, teacher education frequently consists of sporadic and unconnected study and class situations. An individual content weakness of teacher education is the lack of insufficient initiation into evaluation processes. The novice teachers suggest that a student must be provided good-quality and competent guidance during the study years and during his or her induction. There should be a well-organized, structured and systematic induction program for novice teachers. The induction program should be overseen by an organization so that the requirements of a qualified induction can be met. The findings show that the novice teachers find the first year of teaching at comprehensive school emotionally loaded. The teachers experienced teaching as difficult work and found the workload heavy. Nevertheless, they enjoyed their job because, as they said, there were more pleasant than unpleasant things in their school day. Their main feeling at school was the joy of success in teaching. The novice teachers felt satisfaction with their pupils. The teachers experienced the more serious feelings of anger and disgust when serious violence took place. The most difficult situations arose from teaching pupils who had mental health problems. The toughest thing in the teacher´s work was teaching groups that are too heterogeneous. The most awkward problems in group dynamics happened when new immigrants, who spoke only their own languages, were integrated into the groups in the middle of the school year. Teachers wanted to help children who needed special help with learning but restated at the same time that the groups being taught shouldn’t be too heterogeneous. The teachers wished for help from school assistants so that they could personally concentrate more on teaching. Not all the parents took care of their children according to the comprehensive school law. The teachers found it hard to build a confidential relationship between home and school. In this study, novice teachers found it hard to join the teaching staff at school. Some of the teachers on staff were very strong and impulsive, reacting loudly and emotionally. These teachers provoked disagreement, conflicts, power struggles and competition among the other teachers. Although the novice teachers of the study were all qualified teachers, three of them were not interested in a permanent teaching job. For these teachers teaching at a primary school was just a project, a short period in their working life. They will remain in the teaching profession as long as they are learning new things and enjoying their teaching job. This study is an independent part of the research project on Interplay – Connecting Academic Teacher Education and Work, undertaken by the Department of Applied Sciences of Education at the University of Helsinki. Key words: novice teacher, emotions, groups and group dynamics, authority, co-operation between home and school, teacher community, leadership at school, induction, consulting

Androgen receptor in transcriptional regulation and carcinogenesis

Androgens control a variety of developmental processes that create the male phenotype and are important for maintaining male fertility and normal functions of tissues and organs that are not directly involved in procreation. Androgen receptor (AR) that mediates the biological actions of androgens is a member of the nuclear receptor superfamily of ligand-inducible transcription factors. Although AR was cloned over 15 years ago, the mechanisms by which it regulates gene expression are not well understood. A growing body of in vitro experimental evidence suggests that a complex network of proteins is involved in the androgen-dependent transcriptional regulation. However, the process of AR-dependent transcriptional regulation under physiological conditions is largely elusive. In the present study, a series of experiments were performed, including quantitative chromatin immunoprecipitation (ChIP) assays, to investigate AR-mediated transcription process using living prostate cancer cells. Our results show that the loading of AR and recruitment of coactivators and RNA polymerase II (Pol II) to both the promoter and enhancer of AR target genes are a transient and cyclic event that in addition to hyperacetylation, also involves dynamic changes in methylation, phosphorylation of core histone H3 in androgen-treated LNCaP cells. The dynamics of testosterone (T)-induced loading of AR onto the proximal promoters of the genes clearly differed from that loaded onto the distal enhancers. Significantly, more holo-AR was loaded onto the enhancers than the promoters, but the principal Pol II transcription complex was assembled on the promoters. By contrast, the pure antiandrogen bicalutamide (CDX) complexed to AR elicited occupancy of the PSA promoter, but was unable to load onto the PSA enhancer and was incapable of recruiting Pol II, coactivators and following changes of covalent histone modifications. The partial antagonist cyproterone acetate (CPA) and mifepristone (RU486) were capable of promoting AR loading onto both the PSA promoter and enhancer at a comparable efficiency with androgen in LNCaP cells expressing mutant AR. However, CPA- and RU486-bound AR not only recruited Pol II and coactivator p300 and GRIP1 onto the promoter and enhancer, but also recruited the corepressor NCoR onto the promoter as efficiently as CDX. In addition, we demonstrate that both proteasome and protein kinases are implicated in AR-mediated transcription. Even though proteasome inhibitor MG132 and protein kinase inhibitor DRB (5, 6-Dichlorobenzimidazole riboside) can block ligand-dependent accumulation of PSA mRNA with same efficiency, their use results in different molecular profiles in terms of the formation of AR-mediated transcriptional complex. Collectively, these results indicate that transcriptional activation by AR is a complicated process, which includes transient loading of holo-AR and recruitment of Pol II and coregulators accompanied by a cascade of distinct covalent histone modifications; This process involves both the promoter and enhancer elements, as well as other general components of the cell machineries e.g. proteasome and protein kinase; The pure antiandrogen CDX and the partial antagonist CPA and RU486 exhibit clearly different profiles in terms of their ability to induce the formation of AR-dependent transcriptional complexes and the histone modifications associated with the target genes in human prostate cancer cells. Finally, by using quantitative RT-PCR to compare the expression of sixteen AR co-regulators in prostate cancer cell lines, xenografts, and clinical prostate cancer specimens we suggest that AR co-regulators protein inhibitor of activated STAT1 (PIAS1) and steroid receptor coactivator 1(SRC1) could be involved in the progression of prostate cancer.

Phytoplankton quantity as an indicator of eutrophication in Finnish coastal waters : Applications within the Water Framework Directive

The tackling of coastal eutrophication requires water protection measures based on status assessments of water quality. The main purpose of this thesis was to evaluate whether it is possible both scientifically and within the terms of the European Union Water Framework Directive (WFD) to assess the status of coastal marine waters reliably by using phytoplankton biomass (ww) and chlorophyll a (Chl) as indicators of eutrophication in Finnish coastal waters. Empirical approaches were used to study whether the criteria, established for determining an indicator, are fulfilled. The first criterion (i) was that an indicator should respond to anthropogenic stresses in a predictable manner and has low variability in its response. Summertime Chl could be predicted accurately by nutrient concentrations, but not from the external annual loads alone, because of the rapid affect of primary production and sedimentation close to the loading sources in summer. The most accurate predictions were achieved in the Archipelago Sea, where total phosphorus (TP) and total nitrogen (TN) alone accounted for 87% and 78% of the variation in Chl, respectively. In river estuaries, the TP mass-balance regression model predicted Chl most accurately when nutrients originated from point-sources, whereas land-use regression models were most accurate in cases when nutrients originated mainly from diffuse sources. The inclusion of morphometry (e.g. mean depth) into nutrient models improved accuracy of the predictions. The second criterion (ii) was associated with the WFD. It requires that an indicator should have type-specific reference conditions, which are defined as "conditions where the values of the biological quality elements are at high ecological status". In establishing reference conditions, the empirical approach could only be used in the outer coastal water types, where historical observations of Secchi depth of the early 1900s are available. The most accurate prediction was achieved in the Quark. In the inner coastal water types, reference Chl, estimated from present monitoring data, are imprecise - not only because of the less accurate estimation method but also because the intrinsic characteristics, described for instance by morphometry, vary considerably inside these extensive inner coastal types. As for phytoplankton biomass, the reference values were less accurate than in the case of Chl, because it was possible to estimate reference conditions for biomass only by using the reconstructed Chl values, not the historical Secchi observations. An paleoecological approach was also applied to estimate annual average reference conditions for Chl. In Laajalahti, an urban embayment off Helsinki, strongly loaded by municipal waste waters in the 1960s and 1970s, reference conditions prevailed in the mid- and late 1800s. The recovery of the bay from pollution has been delayed as a consequence of benthic release of nutrients. Laajalahti will probably not achieve the good quality objectives of the WFD on time.    The third criterion (iii) was associated with coastal management including the resources it has available. Analyses of Chl are cheap and fast to carry out compared to the analyses of phytoplankton biomass and species composition; the fact which has an effect on number of samples to be taken and thereby on the reliability of assessments. However, analyses on phytoplankton biomass and species composition provide more metrics for ecological classification, the metrics which reveal various aspects of eutrophication contrary to what Chl alone does.

Transition to parenthood after assisted reproductive treatment: Follow-up study of singleton pregnancies

Infertility treatments are relatively easily available in most Western countries today, but the psychological consequences of these high-tech treatments have scarcely been addressed. The purpose of this controlled longitudinal study was to explore the early environment of the infant born by assisted reproductive treatment (ART). We focused on the parents mental well-being, marital relations and experience of parenting. In addition to this, we assessed parent child interaction and parents mental representations of their child after long-standing infertility and several unsuccessful ART attempts. The subjects were infertile couples who achieved a singleton pregnancy by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). The control group comprised of spontaneously conceiving couples with singleton pregnancies. ART women showed fewer depressive symptoms than controls during pregnancy and after delivery, but the difference vanished by the end of the child s first year. ART men consistently had lower levels of anxiety symptoms, sleeping difficulties, and social dysfunction than control men. Control women experienced a decrease in dyadic consensus during the child s first year, which did not happen among ART women. After the child was born, ART men reported a higher level of sexual affection compared with control men. Psychic symptoms and stressful life events were differently related to marital relations in ART and control groups. The parenting experiences of ART mothers were in general at a higher level, compared with controls, and they changed in a positive direction during the child s first year. Fathering experiences were at the same level in both groups, and they changed positively in both groups by the end of the child s first year. The parenting experiences of ART mothers and fathers were more resilient to certain child-related stressors than those of control group. Both mothers and fathers with long-term infertility showed more sensitive behaviour with their child in toddler-age than in infancy. Correspondingly, children s cooperation increased. Mothers often mentioned a fear of miscarriage and difficulty in creating representations of the child during pregnancy. Descriptions of the infants were mainly rich, vivid and loaded with positive features. In conclusion, ART parents in general seem to adapt well to the transition to parenthood. Former infertility and ART do not seem to constitute a risk for parents mental health, marital relations or experience of parenting. Even longstanding infertility with several unsuccessful treatment attempts did not create a risk as regards parenting behaviour or parents mental representations of their child. In this group, however, women were found to have fear for losing the child and difficulty in creating representations of the child during pregnancy, which in some cases may indicate need for psychosocial support. Even though our results are encouraging, infertility and infertility treatments are generally considered as a stressful experience. It is a challenge for health authorities to recognize those couples who need professional help to overcome the distressing experiences of infertility and ART.

Local Politicizations : A Comparison of Finns and French Practicing Democracy

This study examines how do the processes of politicization differ in the Finnish and the French local contexts, and what kinds of consequences do these processes have on the local civic practices, the definitions and redefinitions of democracy and citizenship, the dynamics of power and resistance, and the ways of solving controversies in the public sphere. By means of comparative anthropology of the state , focusing on how democracy actually is practiced in different contexts, politicizations the processes of opening political arenas and recognizing controversy are analyzed. The focus of the study is on local activists engaged in different struggles on various levels of the local public spheres, and local politicians and civil servants participating in these struggles from their respective positions, in two middle-size European cities, Helsinki and Lyon. The empirical analyses of the book compare different political actors and levels of practicing democracy simultaneously. The study is empirically based on four different bodies of material: Ethnographic notes taken during a fieldwork among the activities of several local activist groups; 47 interviews of local activists and politicians; images representing different levels of public portrayals from activist websites (Helsinki N=274, Lyon N=232) and from city information magazines (Helsinki-info N=208, Lyon Citoyen N= 357); and finally, newspaper articles concerning local conflict issues, and reporting on the encounters between local citizens and representatives of the cities (January-June in 2005; Helsingin Sanomat N=96 and Le Progrès N= 102). The study makes three distinctive contributions to the study of current democratic societies: (1) a conceptual one by bringing politicization at the center of a comparison of political cultures, and by considering in parallel the ethnographic group styles theory by Nina Eliasoph and Paul Lichterman, the theory on counter-democracy by Pierre Rosanvallon and the pragmatist justification theory by Luc Boltanski and Laurent Thévenot; (2) an empirical one through the triangulation of ethnographic, thematic interview, visual, and newspaper data through which the different aspects of democratic practices are examined; and (3) a methodological one by developing new ways of analyzing comparative cases an application of Frame Analysis to visual material and the creation of Public Justification Analysis for analyzing morally loaded claims in newspaper reports thus building bridges between cultural, political, and pragmatic sociology. The results of the study indicate that the cultural tools the Finnish civic actors had at their disposal were prone to hinder more than support politicization, whereas the tools the French actors mainly relied on were frequently apt for making politicization possible. This crystallization is defined and detailed in many ways in the analyses of the book. Its consequences to the understanding and future research on the current developments of democracy are multiple, as politicization, while not assuring good results as such, is central to a functioning and vibrant democracy in which injustices can be fixed and new directions and solutions sought collectively.

Loading of itraconazole into porous silica and silicon microparticles: characterization and dissolution tests

Most new drug molecules discovered today suffer from poor bioavailability. Poor oral bioavailability results mainly from poor dissolution properties of hydrophobic drug molecules, because the drug dissolution is often the rate-limiting event of the drug’s absorption through the intestinal wall into the systemic circulation. During the last few years, the use of mesoporous silica and silicon particles as oral drug delivery vehicles has been widely studied, and there have been promising results of their suitability to enhance the physicochemical properties of poorly soluble drug molecules. Mesoporous silica and silicon particles can be used to enhance the solubility and dissolution rate of a drug by incorporating the drug inside the pores, which are only a few times larger than the drug molecules, and thus, breaking the crystalline structure into a disordered, amorphous form with better dissolution properties. Also, the high surface area of the mesoporous particles improves the dissolution rate of the incorporated drug. In addition, the mesoporous materials can also enhance the permeability of large, hydrophilic drug substances across biological barriers. T he loading process of drugs into silica and silicon mesopores is mainly based on the adsorption of drug molecules from a loading solution into the silica or silicon pore walls. There are several factors that affect the loading process: the surface area, the pore size, the total pore volume, the pore geometry and surface chemistry of the mesoporous material, as well as the chemical nature of the drugs and the solvents. Furthermore, both the pore and the surface structure of the particles also affect the drug release kinetics. In this study, the loading of itraconazole into mesoporous silica (Syloid AL-1 and Syloid 244) and silicon (TOPSi and TCPSi) microparticles was studied, as well as the release of itraconazole from the microparticles and its stability after loading. Itraconazole was selected for this study because of its highly hydrophobic and poorly soluble nature. Different mesoporous materials with different surface structures, pore volumes and surface areas were selected in order to evaluate the structural effect of the particles on the loading degree and dissolution behaviour of the drug using different loading parameters. The loaded particles were characterized with various analytical methods, and the drug release from the particles was assessed by in vitro dissolution tests. The results showed that the loaded drug was apparently in amorphous form after loading, and that the loading process did not alter the chemical structure of the silica or silicon surface. Both the mesoporous silica and silicon microparticles enhanced the solubility and dissolution rate of itraconazole. Moreover, the physicochemical properties of the particles and the loading procedure were shown to have an effect on the drug loading efficiency and drug release kinetics. Finally, the mesoporous silicon particles loaded with itraconazole were found to be unstable under stressed conditions (at 38 qC and 70 % relative humidity).

Mesoporous silica- and silicon-based materials as carriers for poorly water soluble drugs

New chemical entities with unfavorable water solubility properties are continuously emerging in drug discovery. Without pharmaceutical manipulations inefficient concentrations of these drugs in the systemic circulation are probable. Typically, in order to be absorbed from the gastrointestinal tract, the drug has to be dissolved. Several methods have been developed to improve the dissolution of poorly soluble drugs. In this study, the applicability of different types of mesoporous (pore diameters between 2 and 50 nm) silicon- and silica-based materials as pharmaceutical carriers for poorly water soluble drugs was evaluated. Thermally oxidized and carbonized mesoporous silicon materials, ordered mesoporous silicas MCM-41 and SBA-15, and non-treated mesoporous silicon and silica gel were assessed in the experiments. The characteristic properties of these materials are the narrow pore diameters and the large surface areas up to over 900 m²/g. Loading of poorly water soluble drugs into these pores restricts their crystallization, and thus, improves drug dissolution from the materials as compared to the bulk drug molecules. In addition, the wide surface area provides possibilities for interactions between the loaded substance and the carrier particle, allowing the stabilization of the system. Ibuprofen, indomethacin and furosemide were selected as poorly soluble model drugs in this study. Their solubilities are strongly pH-dependent and the poorest (< 100 µg/ml) at low pH values. The pharmaceutical performance of the studied materials was evaluated by several methods. In this work, drug loading was performed successfully using rotavapor and fluid bed equipment in a larger scale and in a more efficient manner than with the commonly used immersion methods. It was shown that several carrier particle properties, in particular the pore diameter, affect the loading efficiency (typically ~25-40 w-%) and the release rate of the drug from the mesoporous carriers. A wide pore diameter provided easier loading and faster release of the drug. The ordering and length of the pores also affected the efficiency of the drug diffusion. However, these properties can also compensate the effects of each other. The surface treatment of porous silicon was important in stabilizing the system, as the non-treated mesoporous silicon was easily oxidized at room temperature. Different surface chemical treatments changed the hydrophilicity of the porous silicon materials and also the potential interactions between the loaded drug and the particle, which further affected the drug release properties. In all of the studies, it was demonstrated that loading into mesoporous silicon and silica materials improved the dissolution of the poorly soluble drugs as compared to the corresponding bulk compounds (e.g. after 30 min ~2-7 times more drug was dissolved depending on the materials). The release profile of the loaded substances remained similar also after 3 months of storage at 30°C/56% RH. The thermally carbonized mesoporous silicon did not compromise the Caco-2 monolayer integrity in the permeation studies and improved drug permeability was observed. The loaded mesoporous silica materials were also successfully compressed into tablets without compromising their characteristic structural and drug releasing properties. The results of this research indicated that mesoporous silicon/silica-based materials are promising materials to improve the dissolution of poorly water soluble drugs. Their feasibility in pharmaceutical laboratory scale processes was also confirmed in this thesis.

Kohdennetut nanopartikkelit ja isotooppikuvantaminen syövän hoidossa

Syövän diagnostiikassa ja hoidossa nanopartikkelit voivat toimia kuljetinaineina lääke- ja diagnostisille aineille tai nukleiinihappojaksoille. Kantaja-aineeseen voidaan liittää kohdennusmolekyylejä partikkelien passiivista tai aktiivista kohdennusta varten tai radioleima kuvantamista tai radioterapiaa varten. Kantaja-aineiden avulla voidaan parantaa lääkeaineen fysikaalis-kemiallisia ominaisuuksia ja biologista hyötyosuutta, vähentää systeemisiä sivuvaikutuksia, pidentää lääkeaineen puoliintumisaikaa ja siten harventaa annosteluväliä, sekä parantaa lääkeaineen pääsyä kohdekudokseen. Näin voidaan parantaa kemo- ja radioterapian tehoa ja hoidon onnistumisen todennäköisyyttä. Kirjallisuuskatsauksessa perehdytään nanokantajien rooliin syövän hoidossa. Vuosikymmeniä jatkuneesta tutkimuksesta huolimatta vain kaksi (Eurooppa) tai kolme (Yhdysvallat) nanopartikkeliformulaatiota on hyväksytty markkinoille syövän hoidossa. Ongelmina ovat riittämätön hakeutuminen kohdekudokseen, immunogeenisyys ja nanopartikkelien labiilius. Kokeellisessa osassa tutkitaan in vitro ja hiirillä in vivo 99mTc-leimattujen, PEG-verhoiltujen biotiiniliposomien kaksivaiheista kohdennusta ihmisen munasarjan adenokarsinoomasoluihin. Kohdentamiseen käytetään biotinyloitua setuksimabi-(Erbitux®) vasta-ainetta, joka sitoutuu solujen yli-ilmentämiin EGF-reseptoreihin. Kaksivaiheista kohdennusta verrataan suoraan ja/tai passiiviseen kohdennukseen. Tehokkaampien kuvantamismenetelmien kehitys on vauhdittanut kohdennettujen nanopartikkelien tutkimusta. Isotooppikuvantamista käyttäen pystytään seuraamaan radioleiman jakautumista elimistössä ja kuvantamaan solutasolla tapahtuvia ilmiöitä. Kirjallisuuskatsauksessa perehdytään SPECT- ja PET-kuvantamiseen syövän hoidossa, sekä niiden hyödyntämiseen lääkekehityksessä nanopartikkelien kuvantamisessa. Kyseiset kuvantamismenetelmät erottuvat muista menetelmistä korkean erotuskyvyn, herkkyyden ja helppokäyttöisyyden suhteen. Kokeellisessa osassa 99mTc-leimattujen liposomien distribuutiota hiirissä tutkittiin SPECT-CT-laitteen avulla. Aktiivisuus kasvaimessa, pernassa ja maksassa kvantifioitiin InVivoScope-ohjelman ja gammalaskijan avulla. Tuloksia verrattiin keskenään. In vitro-kokeessa saavutettiin kaksivaiheisella kohdennuksella 2,7- 3,5-kertainen (solulinjasta riippuen) hakeutuminen soluihin kontrolliliposomeihin verrattuna. Kuitenkin suora kohdennus toimi kaksivaiheista kohdennusta paremmin in vitro. In vivo –kokeissa liposomit jakautuivat kasvaimeen tehokkaammin i.p.-annosteltuna kuin i.v.-annosteltuna. Kaksivaiheisella kohdennuksella saavutettiin 1,24-kertainen jakautuminen kasvaimeen (% ID/g kudosta) passiivisesti kohdennettuihin liposomeihin verrattuna. %ID/elin oli kohdennetuilla liposomeilla 5,9 % ja passiivisesti kohdennetuilla 5,4%. Todellinen ero oli siis pieni. InVivoScope:n ja gammalaskijan tulokset eivät korreloineet keskenään. Lisätutkimuksia ja menetelmän optimointia vaaditaan liposomien kohdennuksessa kasvaimeen.

Biocompatibility and biofunctionalization of mesoporous silicon particles

Several of the newly developed drug molecules experience poor biopharmaceutical behavior, which hinders their effective delivery at the proper site of action. Among the several strategies employed in order to overcome this obstacle, mesoporous silicon-based materials have emerged as promising drug carriers due to their ability to improve the dissolution behavior of several poorly water-soluble drugs compounds confined within their pores. In addition to improve the dissolution behavior of the drugs, we report that porous silicon (PSi) nanoparticles have a higher degree of biocompatibility than PSi microparticles in several cell lines studied. In addition, the degradation of the nanoparticles showed its potential to fast clearance in the body. After oral delivery, the PSi particles were also found to transit the intestines without being absorbed. These results constituted the first quantitative analysis of the behavior of orally administered PSi nanoparticles compared with other delivery routes in rats. The self-assemble of a hydrophobin class II (HFBII) protein at the surface of hydrophobic PSi particles endowed the particles with greater biocompatibility in different cell lines, was found to reverse their hydrophobicity and also protected a drug loaded within its pores against premature release at low pH while enabling subsequent drug release as the pH increased. These results highlight the potential of HFBII-coating for PSi-based drug carriers in improving their hydrophilicity, biocompatibility and pH responsiveness in drug delivery applications. In conclusion, mesoporous silicon particles have been shown to be a versatile platform for improving the dissolution behavior of poorly water-soluble drugs with high biocompatibility and easy surface modification. The results of this study also provide information regarding the biofunctionalization of the THCPSi particles with a fungal protein, leading to an improvement in their biocompatibility and endowing them with pH responsive and mucoadhesive properties.