Search

Nanosensitizers having long-lived upconversion emission under near-infrared (NIR) excitation offer unique advantages in terms of reduced background noise and prolonged signal detection for deep tissue therapy of cancer. Herein, we demonstrate a systematic mechanism of energy migration toward achieving long-lived Mn2+ upconversion emission in the multilayered core–shell–shell lattice of NaGdF4:Yb3+,Tm3+,Ca2+/NaGdF4:Yb3+,Ca2+/NaGdF4:Mn2+ upconversion nanoparticles (NPs), following the Yb3+ → Tm3+ → Gd3+ → Mn2+ intermetal ions energy transfer pathway. Furthermore, a rational design of nanosensitizer was achieved by incorporating Er3+ ions into the intermediate shell of multishell NPs, which was subsequently conjugated with the Rose Bengal sensitizer to enable the enhancement in singlet molecular oxygen (1O2) generation under excitation of a 980 nm NIR laser. An intense higher-energy emission in the UV–blue visible region from Tm3+ was achieved by optimizing the amount of Ca2+ in the core–shell NPs, followed by subsequent energy migration to the Mn2+ ion incorporated at the outer shell. The Mn2+ ions were strategically doped in the outer shell of NPs to leverage the catalytic activities of Mn2+ for H2O2 decomposition and decrease the backward energy transfer to the Tm3+ ion. Hence, this approach resulted in a long lifetime of Mn2+ (∼34 ms), attributed to the spin-forbidden 4T1g → 6A1g transition within 3d5 configuration. Additionally, the nanosensitizer demonstrated high 1O2 (∼0.39 μM) generation even at a very low concentration (5 μg/mL) under a laser power of 2 mW cm–2. The hydrogenase-like catalytic activities of Mn2+ exhibited significant oxygen production through decomposition of H2O2. Hence, these findings might contribute to the development of convenient multifunctional nanosensitizers for multimodal bioimaging and therapeutic features, including efficient 1O2 generation and catalytic decomposition of H2O2 (found excessively in a tumor environment) to oxygen for alleviating the hypoxia. [ABSTRACT FROM AUTHOR]

The Pab Formation of Zamzama block, lying in the Lower Indus Basin of Pakistan, is a prominent gas-producing sand reservoir. The optimized production is limited because of water encroachment surrounding the gas-producing wells, thus it is required to distinguish the gas-sand facies from the remainder of the wet sands and shales for additional drilling zones. An approach is adopted based on the relation between petrophysical and elastic properties to characterize the prospect locations. Petro-elastic models (PEMs) for the identified facies were generated to distinguish lithologies in their elastic ranges. Several elastic properties, including p-impedance (11,600-12,100 m/s*g/cc), s-impedance (7,000-7,330 m/s*g/cc), and Vp/Vs ratio (1.57-1.62), were calculated from the simultaneous prestack seismic inversion (SPSI), allowing the identification of gas sands in the field. The inverted elastic attributes and well-based lithologies were incorporated into the Bayesian framework to evaluate the probability of gas sands. To determine the reservoir quality, bulk volumes of PHIE and clay were estimated using elastic volumes trained on well logs by employing Probabilistic neural networking (PNN), which effectively handles heterogeneity effects. The results showed that the channelized gas sands passing through the existing well locations exhibited reduced clay content and maximum effective porosities of 9%, confirming the reservoir's good quality. Such approaches can be widely implemented in producing fields to completely assess lithofacies and achieve maximum production with minimal risks. [ABSTRACT FROM AUTHOR]

Singlet molecular oxygen ( 1 O 2 ) has been reported in wide arrays of applications ranging from optoelectronic to photooxygenation reactions and therapy in biomedical proposals. It is also considered a major determinant of photodynamic therapy (PDT) efficacy. Since the direct excitation from the triplet ground state ( 3 O 2 ) of oxygen to the singlet excited state 1 O 2 is spin forbidden; therefore, a rational design and development of heterogeneous sensitizers is remarkably important for the efficient production of 1 O 2 . For this purpose, quantum dots (QDs) have emerged as versatile candidates either by acting individually as sensitizers for 1 O 2 generation or by working in conjunction with other inorganic materials or organic sensitizers by providing them a vast platform. Thus, conjoining the photophysical properties of QDs with other materials, e.g., coupling/combining with other inorganic materials, doping with the transition metal ions or lanthanide ions, and conjugation with a molecular sensitizer provide the opportunity to achieve high-efficiency quantum yields of 1 O 2 which is not possible with either component separately. Hence, the current review has been focused on the recent advances made in the semiconductor QDs, perovskite QDs, and transition metal dichalcogenide QD-sensitized 1 O 2 generation in the context of ongoing and previously published research work (over the past eight years, from 2015 to 2023)., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)