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There are many different types of targeted therapy for cancer treatment. The method of light mediated targeted therapy that we have developed uses photocaged molecules and photoswitchable peptides. In photocaging, a biologically active molecule is made inactive by the attachment of a photocleavable blocking group. On exposure to UV radiation the photocleavable entity is removed and the biologically active molecule is released. Using this concept we have designed a prodrug that consists of a cell impermeable hydrophilic molecule attached to a photocaged doxorubicin. Upon irradiation with UV light the photosensitive group is removed and cytotoxic doxorubicin is released at the tumor site. This concept has been further modified by attaching receptor binding molecules to the photocaged entity to increase its specificity. A peptide which consists of an azobenzene photoswitch has been used which, in the dark state is randomly coiled and cell impermeable but upon illumination becomes helical and cell permeable and can be used to deliver drugs into the cells. Upon illumination with UV light of suitable wavelength the azobenzene linker will change from a trans to a cis form and this will convert the randomly coiled cell impermeable peptide into an α helical permeable form. Thus a series of peptides have been designed with different arginine mutations which develop an arginine patch in the helical form. This arginine patch would help in cell permeability by interacting with cell surface glycans. The method could potentially be used to deliver drugs into cells in presence of light.

A thorough understanding of the underlying electronic principles guiding the stability and reactivity of clusters has direct implications for the identification of stable clusters for incorporation into clusters-assembled materials with tunable properties. This work explores the electronic principles governing the stability and reactivity of two types of clusters: ligated metal clusters and silicon encapsulated transition metal clusters. In the first case, the reactivity of iodine-protected aluminum clusters, Al13Ix- (x=0-4) and Al14Iy- (y-0-5), with the protic species methanol was studied. The symmetrical ground states of Al13Ix- showed no reactivity with methanol but reactivity was achieved in a higher energy isomer of Al13I2- with iodines on adjacent aluminum atoms – complementary Lewis acid-base active sites were induced on the opposite side of the cluster capable of breaking the O-H bond in methanol. Al14Iy- (y=2-5) react with methanol, but only at the ligated adatom site. Reaction of methanol with Al14- and Al14I- showed that ligation of the adatom was necessary for the reaction to occur there – revealing the concept of a ligand-activated adatom. In the second case, the study focused heavily on CrSi12, a silicon encapsulated transition metal cluster whose stability and the reason for that stability has been debated heavily in the literature. Calculations of the energetic properties of CrSin (n=6-16) revealed both CrSi12 and CrSi14 to have enhanced stability relative to other clusters; however CrSi12 lacks all the traditional markers of a magic cluster. Molecular orbital analysis of each of these clusters showed the CNFEG model to be inadequate in describing their stability. Because the 3dz2 orbital of Cr is unfilled in CrSi12, this cluster has only 16 effective valence electrons, meaning that the 18-electron rule is not applicable. The moderate stability of CrSi12 can be accounted for by the crystal-field splitting of the 3d orbitals, which pushes the 3dz2 orbital up in energy. CrSi14, on the other hand, has 18 effective valence electrons on Cr, minimal 3d-orbital splitting, and does follow the 18-electron rule. A repetition of these calculations with WSin (n=6-16) showed similar results, except WSi12 shows all the markers of a magic cluster, due to the greater crystal-field splitting of 5d orbitals.

Denna forskningsrapport fokuserar på gymnasieskolans laborationer i kemi och hur dessa förändrats under de senaste 10-20 åren. Motivet till att studera detta är ambitionen att få ökad didaktisk förståelse för laborationen som viktigt inslag i kemiundervisningen. I ett större perspektiv kan detta vara av intresse för att analysera om förändringar av gymnasieskolans kemilaborationer kan utgöra en delförklaring till att svenska universitet upplever ett minskat söktryck för kemi på högskolenivå och om delförklaring kan finnas för att Sverige som nation inte når samma resultat i naturvetenskap som vissa andra länder i internationella kunskapsmätningar. Sex erfarna lärare från sex olika skolor har intervjuats om sina upplevelser av kemilaborationen och vad som påverkat dess utveckling. Ramfaktorteorin har varit grundläggande för detta arbete och som analysmetod har fenomenografin valts. Resultaten visar på en stor variation i vad lärare anser påverkat kemilaborationens förändring. Ökat medvetande och högre krav från lagar och förordningar inom säkerhetsområdet samt att lärare upplever sig ha mindre tillgänglig tid för laborationerna framstår som de tydligaste orsakerna till gjorda förändringar. Även kompensation för försämrade praktiska färdigheter hos elever som lämnar grundskolan framkommer som en bakomliggande faktor. Den nya läroplanen Gy 2011, kostnadsöverväganden och kemi­lokalernas beskaffenhet framkom som mindre avgörande för kemilaborationens utveckling.