Perception of Patients on the Waiting List for Total Hip Arthroplasty on the Resumption of Elective Surgeries during the COVID-19 Pandemic.

Objective To analyze the profile and perception of patients on the waiting list for total hip arthroplasty (THA) about performing elective surgeries during the COVID-19 pandemic. Methods From July to November 2021, patients on the THA waiting list were interviewed during outpatient consultations. To compare the groups regarding categorical variables, the Chi-square test or Fisher's exact test was applied, and for quantitative variables the Mann-Whitney test was applied. The results were calculated using the Statistica program version 7. Results 39 patients answered the questionnaire. The mean age was 58.95 years, with 53.85% male. Approximately 60% expressed concern about contracting or transmitting COVID-19 to their family members after hospitalization for THA. 58.9% of patients felt hampered by the delay in scheduling elective surgeries during the pandemic. 23% lost or had a family member who lost their job during the pandemic, with a statistical difference for the group under 60 years old (p = 0.04). Conclusion Most patients were concerned about becoming infected and exposing family members to COVID-19 after surgery and noted damage due to suspensions and delay in scheduling elective surgeries. The economic impact of the pandemic was revealed by the rate of 23% of respondents who lost or had a family member who lost their job during the pandemic, being higher in patients under 60 years of age (p = 0.04).

Perception of Patients on the Waiting List for Total Hip Arthroplasty on the Resumption of Elective Surgeries during the COVID-19 Pandemic / Percepção dos pacientes em lista de espera para artroplastia total do quadril sobre a retomada das cirurgias eletivas durante a pandemia COVID-19

Abstract Objective To analyze the profile and perception ofpatients on the waiting list for total hip arthroplasty (THA) about performing elective surgeries during the COVID-19 pandemic. Methods From July to November 2021, patients on the THA waiting list were interviewed during outpatient consultations. To compare the groups regarding categorical variables, the Chi-square test or Fisher's exact test was applied, and for quantitative variables the Mann-Whitney test was applied. The results were calculated using the Statistica program version 7. Results 39 patients answered the questionnaire. The mean age was 58.95 years, with 53.85% male. Approximately 60% expressed concern about contracting or transmitting COVID-19 to their family members after hospitalization for THA. 58.9% of patients felt hampered by the delay in scheduling elective surgeries during the pandemic. 23% lost or had a family member who lost their job during the pandemic, with a statistical difference for the group under 60 years old (p = 0.04). Conclusion Most patients were concerned about becoming infected and exposing family members to COVID-19 after surgery and noted damage due to suspensions and delay in scheduling elective surgeries. The economic impact of the pandemic was revealed by the rate of 23% of respondents who lost or had a family member who lost their job during the pandemic, being higher in patients under 60 years of age (p = 0.04).

Resumo Objetivo Analisar o perfil e a percepção dos pacientes em lista de espera para artroplastia total do quadril (ATQ) sobre a realização das cirurgias eletivas durante a pandemia pela COVID-19. Métodos De julho a novembro de 2021, foram entrevistados pacientes em lista de espera para ATQ durante consultas ambulatoriais. Para comparar os grupos com relação às variáveis categóricas foi aplicado o Teste Qui-quadrado ou Teste exato de Fisher e para as variáveis quantitativas foi aplicado o teste de Mann-Whitney. Os resultados foram calculados utilizando o programa Statistica versão 7. Resultados 39 pacientes responderam ao questionário. A média de idade foi de 58,95 anos, sendo 53,85% do sexo masculino. Aproximadamente, 60% manifestaram preocupação em contrair ou transmitir COVID-19 aos seus familiares após internação hospitalar para ATQ. 58,9% dos pacientes sentiram-se prejudicados pelo atraso no agendamento das cirurgias eletivas durante a pandemia. 23% perderam ou tiveram algum familiar que perdeu o emprego durante a pandemia, havendo diferença estatística para o grupo com menos de 60 anos (p = 0,04). Conclusão A maioria dos pacientes sentiram preocupação em infectar-se e expor familiares à COVID-19 após a cirurgia e notaram prejuízo pelas suspensões e atraso no agendamento de cirurgias eletivas. O impacto econômico da pandemia revelou-se pela taxa de 23% de entrevistados que perderam ou tiveram algum familiar que perdeu seu emprego durante a pandemia, sendo maior nos pacientes menores de 60 anos (p = 0,04).

Different concentrations of vancomycin with gentamicin loaded PMMA to inhibit biofilm formation of Staphylococcus aureus and their implications.

BACKGROUND: This study aimed to evaluate different concentrations of vancomycin and/or gentamicin loaded polymethylmethacrylate (PMMA) against biofilm formation of Staphylococcus aureus. METHODS: Biofilm production of S. aureus in PMMA loaded with different concentrations of vancomycin and gentamicin were evaluated by quantitative analysis of biofilm cells, scanning electronic microscopy, viability assay, Fourier transform infrared spectroscopy, and checkerboard. Statistical analysis was performed by Mann Whitney test. The difference in colony forming units per mL was significant when p < 0.05. RESULTS: All loaded PMMA presented a reduction in the number of colony forming units per mL (p < 0.05). The gentamicin-loaded PMMA could inhibits the grown of sessile cells (p < 0.05), where the group vancomycin 4 g + gentamicin 500 mg presented a better result. The Fourier transform infrared spectra showed no significant differences, and checkerboard of vancomycin and gentamicin showed synergism. CONCLUSION: Effects against adherence and bacterial development in PMMA loaded with antibiotics were mainly seen in the group vancomycin 4 g + gentamicin 500 mg, and synergic effect can be applied in antibiotic-loaded cement.

A prática de atividade física por acadêmicos de medicina durante a pandemia causada pelo SARS-CoV-2: um estudo transversal / The practice of physical activity of medical students during the pandemic caused by SARS-CoV-2: a cross-sectional study

Introdução: o contexto de pandemia instaurada pelo SARS-CoV-2 acarretou um cenário de isolamento social, dificultando a prática de atividade física regular. Somado a isso, os estudantes de Medicina ainda possuem uma carga horária sobrecarregada. O objetivo do trabalho foi conhecer a qualidade de vida e a prevalência da prática de atividade física e seus efeitos durante o período de pandemia em acadêmicos de Medicina. Métodos: estudo observacional transversal realizado a partir da aplicação do questionário "Prática de atividade física por acadêmicos de Medicina durante a pandemia" em 286 estudantes de ambos os sexos, de todos os períodos de uma faculdade. Resultados: notou-se que os participantes, cursando Medicina com ensino remoto, que tinham mais motivação e tempo livre praticavam mais atividade física, enquanto os participantes que tinham menos motivação e tempo livre diminuíram a prática no período analisado. Discussão: Os estudantes compreendem que a prática de atividade física é benéfica, mesmo ela sendo impedida por cargas horárias extenuantes, até mesmo devido à educação que recebem durante a graduação. Conclusão: constatou-se que acadêmicos de Medicina que possuem aulas de educação remota durante o período estabelecido de isolamento social, consideraram apresentar mais tempo livre para a prática de atividade física. Entretanto, nem todos dedicaram esse tempo para a realização de exercícios [au]

Introduction: the context of the SARS-CoV-2 pandemic led to a scenario of social isolation, hindering the practice of regular physical activity. In addition, medical students still have a very high workload. The objective of this study was to assess the quality of life and the prevalence of physical activity and its effects among medical students during the pandemic period. Methods: cross-sectional observational study conducted through the application of the questionnaire "Engagement in physical activity among medical students during the pandemic" in 286 students of both genders, from all course periods. Results: it was found that the participants on remote medical training who had more motivation and free time exercised more, while the participants who had less motivation and free time decreased their practice of exercises in the analyzed period. Discussion: Students understand that physical activity is beneficial, even though it is hindered by strenuous workloads, due to the education they receive in the course. Conclusion: it was found that medical students who had remote classes during the period of social isolation considered they had more free time for the practice of exercises. However, not all of the dedicated this time to physical activity [au]

Arthroscopic Treatment of Femoroacetabular Impingement in Slipped Capital Femoral Epiphysiolysis: A Case Report.

Slipped capital femoral epiphysiolysis (SCFE) may result in femoroacetabular impingement (FAI) of the hip in up to one third of the cases. Residual deformity of the cam-type, or "pistol-grip", is associated with chondrolabral injury, resulting in pain, functional disability, and early osteoarthritis. The arthroscopic treatment with osteochondroplasty proved to be beneficial in a selected case of FAI secondary to SCFE.

Nanojet Trapping of a Single Sub-10 nm Upconverting Nanoparticle in the Full Liquid Water Temperature Range.

Upconverting nanoparticles (UCNPs) have been used as optical probes in a great variety of scenarios ranging from cells to animal models. When optically trapped, a single UCNP can be remotely manipulated making possible, for instance, thermal scanning in the surroundings of a living cell. When conventional optics is used, the stability of an optically trapped UCNP is very limited. Its reduced size leads to optical potentials comparable to thermal energy, and up to now, stable optical trapping of a UCNP has been demonstrated only close to room temperature. This fact limits their use above room temperature, for instance, the use to investigate protein denaturalization that occurs in the 40-50 °C range. In this work, stable optical trapping of a single UCNP in the 20-90 °C range has been demonstrated by using a photonic nanojet. The use of an optically trapped microsphere makes it possible to overcome the diffraction limit producing another optical trap of smaller size and enhanced strength. This simple strategy leads not only to an improvement in the thermal stability of the optical trap but also to an enhancement of the emission intensity generated by the optically trapped UCNP.

Reliability of rare-earth-doped infrared luminescent nanothermometers.

The use of infrared-emitting rare-earth-doped luminescent nanoparticles as nanothermometers has attracted great attention during the last few years. The scientific community has identified rare-earth-doped luminescent nanoparticles as one of the most sensitive and versatile systems for contactless local temperature sensing in a great variety of fields, but especially in nanomedicine. Researchers are nowadays focused on the design and development of multifunctional nanothermometers with new spectral operation ranges, outstanding brightness, and enhanced sensitivities. However, no attention has been paid to the assessment of the actual reliability of the measurements provided by rare-earth-doped luminescent nanothermometers. In fact, it is assumed that they are ideal temperature sensors. Nevertheless, this is far from being true. In this work we demonstrate that the emission spectra of rare-earth-doped nanothermometers can be affected by numerous environmental and experimental factors. These include the numerical aperture of the optical elements used for their optical excitation and luminescence collection, the local concentration of nanothermometers, optical length variations, self-absorption of the luminescence by the nanothermometers themselves, and solvent optical absorption. This work concludes that rare-earth-doped luminescent nanothermometers are not as reliable as thought and, consequently, special care has to be taken when extracting temperature estimations from the variation of their emission spectra.

Periacetabular hip osteotomy for residual dysplasia treatment: preliminary results.

OBJECTIVE: To evaluate whether the change in the CE angle of Wiberg and the acetabular index after Ganz periacetabular osteotomy is statistically significant. METHODS: The pre- and postoperative CE angle of Wiberg and acetabular index of 14 hips operated at a tertiary hospital in Curitiba, Paraná, Brazil were evaluated. RESULTS: The postoperative measurements showed significant differences in relation to the preoperative period. There was a significant reduction in the CE angle of Wiberg in the postoperative period, as well as in the acetabular index. These differences were statistically significant for both the right and left sides. CONCLUSION: The radiographic evaluation of patients submitted to Ganz periacetabular osteotomy presented some statistically significant results; however, a larger sample is still necessary.

OBJETIVO: Avaliar se a mudança do ângulo CE de Wiberg e do índice acetabular após a osteotomia periacetabular de Ganz é estatisticamente significativa. MÉTODOS: Foram avaliados os ângulos CE de Wiberg e índice acetabular pré- e pós-operatórios de 14 quadris operados em um hospital terciário de Curitiba, Paraná. RESULTADOS: As medidas do pós-operatório apresentaram diferenças significativas em relação ao pré-operatório. Observou-se um aumento significativo no ângulo CE de Wiberg no pós-operatório e uma redução significativa no índice acetabular. Essas diferenças foram estatisticamente significativas tanto para o lado direito como para o lado esquerdo. CONCLUSÃO: A avaliação radiográfica dos pacientes submetidos à osteotomia periacetabular de Ganz apresentou alguns resultados estatisticamente significativos, porém ainda há necessidade de uma amostra maior.

Periacetabular hip osteotomy for residual dysplasia treatment: preliminary results / Osteotomia periacetabular do quadril para tratamento da displasia residual: resultados preliminares

ABSTRACT Objective To evaluate whether the change in the CE angle of Wiberg and the acetabular index after Ganz periacetabular osteotomy is statistically significant. Methods The pre- and postoperative CE angle of Wiberg and acetabular index of 14 hips operated at a tertiary hospital in Curitiba, Paraná, Brazil were evaluated. Results The postoperative measurements showed significant differences in relation to the preoperative period. There was a significant reduction in the CE angle of Wiberg in the postoperative period, as well as in the acetabular index. These differences were statistically significant for both the right and left sides. Conclusion The radiographic evaluation of patients submitted to Ganz periacetabular osteotomy presented some statistically significant results; however, a larger sample is still necessary.

RESUMO Objetivo Avaliar se a mudança do ângulo CE de Wiberg e do índice acetabular após a osteotomia periacetabular de Ganz é estatisticamente significativa. Métodos Foram avaliados os ângulos CE de Wiberg e índice acetabular pré- e pós-operatórios de 14 quadris operados em um hospital terciário de Curitiba, Paraná. Resultados As medidas do pós-operatório apresentaram diferenças significativas em relação ao pré-operatório. Observou-se um aumento significativo no ângulo CE de Wiberg no pós-operatório e uma redução significativa no índice acetabular. Essas diferenças foram estatisticamente significativas tanto para o lado direito como para o lado esquerdo. Conclusão A avaliação radiográfica dos pacientes submetidos à osteotomia periacetabular de Ganz apresentou alguns resultados estatisticamente significativos, porém ainda há necessidade de uma amostra maior.

Radiographic evaluation of cementation technique using polished, conical, triple-tapered femoral stem in hip arthroplasty.

OBJECTIVE: To radiographically evaluate the quality of cementation and implantation technique using a polished, triple-tapered femoral stem in total hip arthroplasty (THA). METHOD: Retrospective study with radiographic evaluation of 86 hips in 83 patients who underwent to primary THA with the triple-tapered cemented femoral stem C-Stem (DePuy Orthopedics, Warsaw, Indiana). Cases with at least one-year of follow-up were included, and data related to preoperative, immediate postoperative, and late postoperative radiographic evolution were recorded. This study analyzed, among others, the proximal femoral anatomy, the quality of cementation as described by Barrack, and the implant positioning. Cementation was also evaluated and quantified in the Gruen zones with one-year of follow-up. RESULTS: The mean age was 62.85 years. Proximal femoral anatomical conformation was Dorr type A in 34 (39.53%) cases, type B in 52 (60.46%), and no type C cases were found. Five (5.81%) cases were defined as type A by Barrack's cementation classification system, 46 (56.49%) type B, 27 (31.40%) type C, and eight (9.30%) type D. The greatest cement mantle thickness was observed in zones four (15.53 mm) and 11 (15.64 mm), and the smallest in zone nine (3.51 mm). Positioning in varus was observed in eight (9.3%) cases, valgus in 25 (29%), forward deviation in two (5%), and backward deviation in 55 (63.95%). CONCLUSIONS: The C-Stem femoral system presented satisfactory results related to cementation pattern, positioning, osteolysis, and stress shielding with regard to literature referring to double-tapered or triple-tapered models, demonstrating to be a safe method, with a predictable and reliable cementing pattern.

OBJETIVO: Avaliar radiograficamente a qualidade da técnica de cimentação e implantação de hastes femorais polidas e tripla cunha em artroplastias totais do quadril (ATQ). MÉTODO: Estudo retrospectivo com avaliação de radiografias de 86 quadris em 83 pacientes submetidos à ATQ com componente femoral cimentado polido em tripla cunha C-Stem (DePuy Orthopaedics, Varsóvia, Ind.). Incluímos casos com pelo menos um ano de seguimento, foram registrados dados relacionados à evolução radiográfica pré-operatória, pós-operatória imediata e pós-operatória tardia. Avaliamos, entre outros dados, a anatomia do fêmur, a qualidade da cimentação segundo descrito por Barrack e o posicionamento da haste. A cimentação também foi avaliada e quantificada em cada zona de Gruen com um ano de seguimento. RESULTADOS: A idade média foi de 62,85 anos. A conformação do fêmur proximal foi do tipo A de Dorr em 34 (39,53%) casos, tipo B em 52 (60,46%) e não foram observados casos do tipo C. Cinco (5,81%) casos foram definidos como tipo A segundo a classificação de cimentação de Barrack, 46 (56,49%) tipo B, 27 (31,40%) tipo C e oito (9,30%) tipo D. A maior espessura média do manto foi observada nas zonas 4 (15,53 mm) e 11 (15,64 mm), a menor foi na zona 9 (3,51 mm). Foi observado posicionamento em varo em oito (9,3%) casos e em valgo em 25 (29%). CONCLUSÃO: A haste femoral C-Stem apresentou resultados satisfatórios quanto ao padrão de cimentação, posicionamento, à presença de osteólise e stress shielding, tanto em relação à literatura referente aos modelos em dupla cunha quanto referente ao mesmo modelo de implante, mostrou-se um método seguro e com padrão de cimentação previsível e confiável.

Radiographic evaluation of cementation technique using polished, conical, triple-tapered femoral stem in hip arthroplasty / Avaliação radiográfica da técnica de cimentação com haste femoral cônica polida e tripla cunha em artroplastia do quadril

Abstract Objective To radiographically evaluate the quality of cementation and implantation technique using a polished, triple-tapered femoral stem in total hip arthroplasty (THA). Method Retrospective study with radiographic evaluation of 86 hips in 83 patients who underwent to primary THA with the triple-tapered cemented femoral stem C-Stem (DePuy Orthopedics, Warsaw, Indiana). Cases with at least one-year of follow-up were included, and data related to preoperative, immediate postoperative, and late postoperative radiographic evolution were recorded. This study analyzed, among others, the proximal femoral anatomy, the quality of cementation as described by Barrack, and the implant positioning. Cementation was also evaluated and quantified in the Gruen zones with one-year of follow-up. Results The mean age was 62.85 years. Proximal femoral anatomical conformation was Dorr type A in 34 (39.53%) cases, type B in 52 (60.46%), and no type C cases were found. Five (5.81%) cases were defined as type A by Barrack's cementation classification system, 46 (56.49%) type B, 27 (31.40%) type C, and eight (9.30%) type D. The greatest cement mantle thickness was observed in zones four (15.53 mm) and 11 (15.64 mm), and the smallest in zone nine (3.51 mm). Positioning in varus was observed in eight (9.3%) cases, valgus in 25 (29%), forward deviation in two (5%), and backward deviation in 55 (63.95%). Conclusions The C-Stem femoral system presented satisfactory results related to cementation pattern, positioning, osteolysis, and stress shielding with regard to literature referring to double-tapered or triple-tapered models, demonstrating to be a safe method, with a predictable and reliable cementing pattern.

Resumo Objetivo Avaliar radiograficamente a qualidade da técnica de cimentação e implantação de hastes femorais polidas e tripla cunha em artroplastias totais do quadril (ATQ). Método Estudo retrospectivo com avaliação de radiografias de 86 quadris em 83 pacientes submetidos à ATQ com componente femoral cimentado polido em tripla cunha C-Stem (DePuy Orthopaedics, Varsóvia, Ind.). Incluímos casos com pelo menos um ano de seguimento, foram registrados dados relacionados à evolução radiográfica pré-operatória, pós-operatória imediata e pós-operatória tardia. Avaliamos, entre outros dados, a anatomia do fêmur, a qualidade da cimentação segundo descrito por Barrack e o posicionamento da haste. A cimentação também foi avaliada e quantificada em cada zona de Gruen com um ano de seguimento. Resultados A idade média foi de 62,85 anos. A conformação do fêmur proximal foi do tipo A de Dorr em 34 (39,53%) casos, tipo B em 52 (60,46%) e não foram observados casos do tipo C. Cinco (5,81%) casos foram definidos como tipo A segundo a classificação de cimentação de Barrack, 46 (56,49%) tipo B, 27 (31,40%) tipo C e oito (9,30%) tipo D. A maior espessura média do manto foi observada nas zonas 4 (15,53 mm) e 11 (15,64 mm), a menor foi na zona 9 (3,51 mm). Foi observado posicionamento em varo em oito (9,3%) casos e em valgo em 25 (29%). Conclusão A haste femoral C-Stem apresentou resultados satisfatórios quanto ao padrão de cimentação, posicionamento, à presença de osteólise e stress shielding, tanto em relação à literatura referente aos modelos em dupla cunha quanto referente ao mesmo modelo de implante, mostrou-se um método seguro e com padrão de cimentação previsível e confiável.

Citrate-stabilized lanthanide-doped nanoparticles: brain penetration and interaction with immune cells and neurons.

AIM: To unravel key aspects of the use of lanthanide-doped nanoparticles (NPs) in biomedicine, the interaction with immune and brain cells. MATERIALS & METHODS: Effects of citrate-stabilized CaF2 and SrF2: Yb, Er NPs (13-15 nm) on human dendritic cells and neurons were assessed in vitro. In vivo distribution was analyzed in mice at tissue and ultrastructural levels, and with glia immunophenotyping. RESULTS: The NPs did not elicit dendritic cell activation and were internalized by cultured neurons, without viability changes. After intravenous injection, NPs were found in the brain parenchyma, without features of glial neuroinflammatory response. CONCLUSION: Lanthanide-doped NPs do not activate cells protagonists of systemic and brain immune responses, are endocytosed by neurons and can cross an intact blood-brain barrier.

Paramagnetic Nanoparticles Leave Their Mark on Nuclear Spins of Transiently Adsorbed Proteins.

The successful application of nanomaterials in biosciences necessitates an in-depth understanding of how they interface with biomolecules. Transient associations of proteins with nanoparticles (NPs) are accessible by solution NMR spectroscopy, albeit with some limitations. The incorporation of paramagnetic centers into NPs offers new opportunities to explore bio-nano interfaces. We propose NMR paramagnetic relaxation enhancement as a new tool to detect NP-binding surfaces on proteins with increased sensitivity, also extending the applicability of NMR investigations to heterogeneous biomolecular mixtures. The adsorption of ubiquitin on gadolinium-doped fluoride-based NPs produced residue-specific NMR line-broadening effects mapping to a contiguous area on the surface of the protein. Importantly, an identical paramagnetic fingerprint was observed in the presence of a competing protein-protein association equilibrium, exemplifying possible interactions taking place in crowded biological media. The interaction was further characterized using isothermal titration calorimetry and upconversion emission measurements. The data indicate that the used fluoride-based NPs are not biologically inert but rather are capable of biomolecular recognition.

Enhancing optical forces on fluorescent up-converting nanoparticles by surface charge tailoring.

3D remote control of multifunctional fluorescent up-converting nanoparticles (UCNPs) using optical forces is being required for a great variety of applications including single-particle spectroscopy, single-particle intracellular sensing, controlled and selective light-activated drug delivery and light control at the nanoscale. Most of these potential applications find a serious limitation in the reduced value of optical forces (tens of fN) acting on these nanoparticles, due to their reduced dimensions (typically around 10 nm). In this work, this limitation is faced and it is demonstrated that the magnitude of optical forces acting on UCNPs can be enhanced by more than one order of magnitude by a controlled modification of the particle/medium interface. In particular, substitution of cationic species at the surface by other species with higher mobility could lead to UCNPs trapping with constants comparable to those of spherical metallic nanoparticles.

Structural plasticity of calmodulin on the surface of CaF2 nanoparticles preserves its biological function.

Nanoparticles are increasingly used in biomedical applications and are especially attractive as biocompatible and biodegradable protein delivery systems. Herein, the interaction between biocompatible 25 nm CaF2 nanoparticles and the ubiquitous calcium sensor calmodulin has been investigated in order to assess the potential of these particles to serve as suitable surface protein carriers. Calmodulin is a multifunctional messenger protein that activates a wide variety of signaling pathways in eukaryotic cells by changing its conformation in a calcium-dependent manner. Isothermal titration calorimetry and circular dichroism studies have shown that the interaction between calmodulin and CaF2 nanoparticles occurs with physiologically relevant affinity and that the binding process is fully reversible, occurring without significant alterations in protein secondary and tertiary structures. Experiments performed with a mutant form of calmodulin having an impaired Ca(2+)-binding ability in the C-terminal lobe suggest that the EF-hand Ca(2+)-binding motifs are directly involved in the binding of calmodulin to the CaF2 matrix. The residual capability of nanoparticle-bound calmodulin to function as a calcium sensor protein, binding to and altering the activity of a target protein, was successfully probed by biochemical assays. Even if efficiently carried by CaF2 nanoparticles, calmodulin may dissociate, thus retaining the ability to bind the peptide encompassing the putative C-terminal calmodulin-binding domain of glutamate decarboxylase and activate the enzyme. We conclude that the high flexibility and structural plasticity of calmodulin are responsible for the preservation of its function when bound in high amounts to a nanoparticle surface.

Nanodevice-induced conformational and functional changes in a prototypical calcium sensor protein.

Calcium (Ca(2+)) plays a major role in a variety of cellular processes. Fine changes in its concentration are detected by calcium sensor proteins, which adopt specific conformations to regulate their molecular targets. Here, two distinct nanodevices were probed as biocompatible carriers of Ca(2+)-sensors and the structural and functional effects of protein-nanodevice interactions were investigated. The prototypical Ca(2+)-sensor recoverin (Rec) was incubated with 20-25 nm CaF2 nanoparticles (NPs) and 70-80 nm liposomes with lipid composition similar to that found in photoreceptor cells. Circular dichroism and fluorescence spectroscopy were used to characterize changes in the protein secondary and tertiary structure and in thermal stability upon interaction with the nanodevice, both in the presence and in the absence of free Ca(2+). Variations in the hydrodynamic diameter of the complex were measured by dynamic light scattering and the residual capability of the protein to act as a Ca(2+)-sensor in the presence of NPs was estimated spectroscopically. The conformation, thermal stability and Ca(2+)-sensing capability of Rec were all significantly affected by the presence of NPs, while liposomes did not significantly perturb Rec conformation and function, allowing reversible binding. NP-bound Rec maintained an all-helical fold but showed lower thermal stability and high cooperativity of unfolding. Our analysis can be proficiently used to validate the biocompatibility of other nanodevices intended for biomedical applications involving Ca(2+)-sensors.

Simple, common but functional: biocompatible and luminescent rare-earth doped magnesium and calcium hydroxides from miniemulsion.

Nanostructured (d∼ 20-35 nm) and highly luminescent Ca(OH)2:Ln and Mg(OH)2:Ln (Ln = EuIII, SmIII, TbIII, Mg(Ca)/Ln = 20 : 1 atomic) nanostructures were obtained in inverse (water in oil - w/o) miniemulsion (ME), by exploiting the nanosized compartments of the droplets to spatially confine the hydroxide precipitation in basic environment (NaOH). The functional nanostructures were prepared using different surfactants (Span80 (span) and a mixture of Igepal co-630 and Brij 52 (mix)) to optimise ME stability and hydroxide biocompatibility as well as tune the droplet sizes. X-Ray diffraction (XRD) analyses testify the achievement of a pure brucite-Mg(OH)2-phase and pure portlandite-Ca(OH)2-phase with a high degree of crystallinity. Besides structural characterisations, the products were thoroughly characterised by means of several and complementary techniques (dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), micro-Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS) and Fourier transform infrared spectroscopy (FT-IR)) to assess their chemico-physical properties as well as their morphological and microstructural features. The stoichiometry of the doped systems was confirmed using ICP-MS measurements. Finally, the cytotoxicity of the nanoparticles was assessed by in vitro tests using ES2 cells in order to provide preliminary data on the biocompatibility of this kind of nanoparticles. The luminescence of the Eu-doped and Tb-doped materials is clearly visible to the naked eye in the red and green regions, respectively, corroborating their employment as materials for imaging in the optical window of interest.

Multifunctional nanoprobes based on upconverting lanthanide doped CaF2: towards biocompatible materials for biomedical imaging.

Water dispersible Gd3+,Yb3+,Er3+ and Gd3+,Yb3+,Tm3+ doped CaF2 nanoparticles (NPs) were prepared by one-pot hydrothermal synthesis using citrate ions as capping agents without the need for any post-synthesis reaction. UC emissions are easily observed in the visible and infrared regions upon NIR diode laser excitation at 980 nm. EPR spectroscopy confirms the substitutional nature of the rare-earth doping, while magnetometric studies reveal that the NPs have a useful magnetization. MRI experiments conducted in vivo show that after 40 min from the injection, the NPs localize in the liver and spleen. Electron microscopy images of liver tissue reveal that the NPs are located in the Kupffer cells, although a small amount is also found in the hepatocytes. An excitation with a 980 nm emission on the excised liver and epithelial tissue induces clearly visible UC emission. The local temperature upon 980 nm irradiation was monitored in situ and it was found to increase slowly with the exposure time, maintaining under 1-2 °C for less than 60 second exposure. The NPs show a low toxicity towards cultured HeLa cells and human primary dendritic cells (DCs), and did not induce pro-inflammatory cytokine secretion by cultured human DCs, indicating that the NPs do not cause relevant adverse reactions in immune cells. Therefore, the present NPs are suitable candidates to be efficiently used in surgery applications, where spatial resolution and lack of harmful effects on human health are important issues.

PEG-capped, lanthanide doped GdF3 nanoparticles: luminescent and T2 contrast agents for optical and MRI multimodal imaging.

A facile method for the synthesis of water dispersible Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped upconverting GdF(3) nanoparticles is reported. Strong upconversion emissions are observed in the red (for Er/Yb doped) and near-infrared (for Tm/Yb doped) regions upon laser excitation at 980 nm. The PEG coating ensures a good dispersion of the system in water and reduces the radiationless de-excitation of the excited states of the Er(3+) and Tm(3+) ions by water molecules. The r(2) relaxivity values are quite high with respect to the common T(2)-relaxing agents (22.6 ± 3.4 mM(-1) s(-1) and 15.8 ± 3.4 mM(-1) s(-1) for the Tm/Yb and Er/Yb doped samples, respectively), suggesting that the present NPs can be interesting as T(2) weighted contrast agents for proton MRI purpose. Preliminary experiments conducted in vitro, in stem cell cultures, and in vivo, after subcutaneous injection of the lanthanide-doped GdF(3) NPs, indicate scarce toxic effects. After an intravenous injection in mice, the GdF(3) NPs localize mainly in the liver. The present results indicate that the present Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped GdF(3) NPs are suitable candidates to be efficiently used as bimodal probes for both in vitro and in vivo optical and magnetic resonance imaging.

NIR-to-NIR two-photon excited CaF2:Tm3+,Yb3+ nanoparticles: multifunctional nanoprobes for highly penetrating fluorescence bio-imaging.

In this study, we report on the remarkable two-photon excited fluorescence efficiency in the "biological window" of CaF(2):Tm(3+),Yb(3+) nanoparticles. On the basis of the strong Tm(3+) ion emission (at around 800 nm), tissue penetration depths as large as 2 mm have been demonstrated, which are more than 4 times those achievable based on the visible emissions in comparable CaF(2):Er(3+),Yb(3+) nanoparticles. The outstanding penetration depth, together with the fluorescence thermal sensitivity demonstrated here, makes CaF(2):Tm(3+),Yb(3+) nanoparticles ideal candidates as multifunctional nanoprobes for high contrast and highly penetrating in vivo fluorescence imaging applications.