Di-cationic Zn(II)-phthalocyanines (ZnPcs) are promising photosensitizers for the photodynamic therapy (PDT) of cancers and for photoinactivation of viruses and bacteria. Pegylation of photosensitizers in general enhances their water-solubility and tumor cell accumulation. A series of pegylated di-cationic ZnPcs were synthesized from conjugation of a low molecular weight PEG group to a pre-formed Pc macrocycle, or by mixed condensation involving a pegylated phthalonitrile. All pegylated ZnPcs were highly soluble in polar organic solvents but were insoluble in water; they have intense Q absorptions centered at 680 nm and fluorescence quantum yields of ca. 0.2 in DMF. The non-pegylated di-cationic ZnPc 6a formed large aggregates, which were visualized by atomic force microscopy. The cytotoxicity, cellular uptake and subcellular distribution of all cationic ZnPcs were investigated in human carcinoma HEp2 cells. The most phototoxic compounds were found to be the α-substituted Pcs. Among these, Pcs 4a and 16a were the most effective (IC50 ca. 10 μM at 1.5 J/cm2), in part due to the presence of a PEG group and the two positive charges in close proximity (separated by an ethylene group) in these macrocycles. The β-substituted ZcPcs 6b and 4b accumulated the most within HEp2 cells but had low photocytoxicity (IC50 > 100 μM at 1.5 J/cm2), possibly as a result of their lower electron density of the ring and more extended conformations compared with the α-substituted Pcs. The results show that the charge distribution about the Pc macrocycle and the intracellular localization of the cationic ZnPcs mainly determine their photodynamic activity.

Visible light photoredox catalysis was combined with immersion particle lithography to prepare polynitrophenylene organic films on Au(111) surfaces, forming a periodic arrangement of nanopores. Surfaces masked with mesospheres were immersed in solutions of p-nitrobenzenediazonium tetrafluoroborate and irradiated with blue LEDs in the presence of the photoredox catalyst Ru(bpy)3(PF6)2 to produce p-nitrophenyl radicals that graft onto gold substrates. Surface masks of silica mesospheres were used to protect small, discrete regions of the Au(111) surface from grafting. Nanopores were formed where the silica mesospheres touched the surface; the mask effectively protected nanoscopic local areas from the photocatalysis grafting reaction. Further reaction of the grafted arenes with aryl radicals resulted in polymerization to form polynitrophenylene structures with thicknesses that were dependent on both the initial concentration of diazonium salt and the duration of irradiation. Photoredox catalysis with visible light provides mild, user-friendly conditions for the reproducible generation of multilayers with thicknesses ranging from 2 to 100 nm. Images acquired with atomic force microscopy (AFM) disclose the film morphology and periodicity of the polymer nanostructures. The exposed sites of the nanopores provide a baseline to enable local measurements of film thickness with AFM. The resulting films of polynitrophenylene punctuated with nanopores provide a robust foundation for further chemical steps. Spatially selective binding of mercaptoundecanoic acid to exposed sites of Au(111) was demonstrated, producing a periodic arrangement of thiol-based nanopatterns within a matrix of polynitrophenylene.

We introduce an approach to synthesize rare earth oxide nanoparticles using high temperature without aggregation of the nanoparticles. The dispersity of the nanoparticles is controlled at the nanoscale by using small organosilane molds as reaction containers. Zeptoliter reaction vessels prepared from organosilane self-assembled monolayers (SAMs) were used for the surface-directed synthesis of rare earth oxide (REO) nanoparticles. Nanopores of octadecyltrichlorosilane were prepared on Si(111) using particle lithography with immersion steps. The nanopores were filled with a precursor solution of erbium and yttrium salts to confine the crystallization step to occur within individual zeptoliter-sized organosilane reaction vessels. Areas between the nanopores were separated by a matrix film of octadecyltrichlorosilane. With heating, the organosilane template was removed by calcination to generate a surface array of erbium-doped yttria nanoparticles. Nanoparticles synthesized by the surface-directed approach retain the periodic arrangement of the nanopores formed from mesoparticle masks. While bulk rare earth oxides can be readily prepared by solid state methods at high temperature (>900 °C), approaches for preparing REO nanoparticles are limited. Conventional wet chemistry methods are limited to low temperatures according to the boiling points of the solvents used for synthesis. To achieve crystallinity of REO nanoparticles requires steps for high-temperature processing of samples, which can cause self-aggregation and dispersity in sample diameters. The facile steps for particle lithography address the problems of aggregation and the requirement for high-temperature synthesis.

The techniques learned in a laboratory translate into strong critical thinking aptitudes as well as adeptness in complex problem-solving within research. Typically, these laboratory skills are not acquired until a budding scientist enters graduate school since many undergraduate laboratories are more procedural than investigative. Therefore, the module in discussion was designed to aid students in developing competence toward thinking like a scientist. Through utilization of an inquiry-based approach, a laboratory involving high performance liquid chromatography was transformed into a blended online learning experiment. While students were provided in-class time to interact with their peers and the instructor and TA, the majority of the work and development was done outside of class. All background information and protocols were provided outside of the lab via an online course management system including the PowerPoint videos that students used to prepare for the experiment. The students used those materials to ultimately determine the identity and number of different steroids in an unknown sample. The objective was to determine if this approach promoted the metacognitive skills of students and encourage the use of argumentative skills when presenting and justifying claims and data.

Lateral flow assays (LFAs) have been used extensively for diagnosis of various diseases and conditions because they are inexpensive, rapid, robust, and easy to use. Incorporating LFAs into undergraduate chemistry courses could enrich the curricula by providing the students with a real-world application of analytical chemistry concepts, particularly why point of care diagnostics can give false positives and false negatives. We developed an LFA module for a class of 25 undergraduate analytical chemistry students that used a hybrid (part face-to-face (F2F) and part remote) learning format. The laboratory consisted of two sessions, the first of which was conducted F2F and the second of which was conducted remotely via conferencing software. In the laboratory session, the students ran LFAs that were designed in house and that detected a well-established malaria biomarker. The students subsequently captured photos and quantified the LFA signal using a mobile-friendly web application that allows for quantification of LFA test and control lines using a smartphone camera. During the second remote session, the students constructed receiver operating characteristic curves, and this activity was used to foster a broader discussion among the students about diagnostic specificity and sensitivity. Following the conclusion of the module, we had the students complete an anonymous survey where students reported they felt an increase in comprehension regarding the topics of LFAs and diagnostic specificity versus sensitivity. We have included all data and protocols to perform this lab and believe this module is well-suited as an in-person, hybrid, or remoteonly lab or even as a lecture content supplement.