Contrary to the belief of the chemistry community, intense charge transfer is observed between meta-oriented donor–acceptor moieties in ultrasmall single-benzenic fluorophores. Red emission in any solvent has so far been reported with molecular fluorophores having the lowest molecular weight (MW) of 252.5 Da; however, we have achieved the same with a meta-fluorophore having an MW of only 203.1 Da. Red emission in a nonpolar solvent has so far been reported with a fluorophore having a minimum MW of 464.5 Da, but we have achieved the same with a meta-fluorophore having an MW of only 255.3 Da. Intense Stokes (260 nm) and solvatochromic (160 nm) shifts, high magnitudes of fluorescence quantum yield (>0.4), and excited-state lifetime (>16 ns) have been obtained in these single-benzenic meta-fluorophores, and these values are comparatively much higher in comparison to corresponding o-/p-fluorophores. These extraordinary meta-fluorophores have been employed to measure subcellular nanopolarity in live stem cells toward cost-effective white fluorescent ink and white light-emitting diodes (LEDs) in solid state.

The smallest fluorophore reported in literature to emit in the red has a MW > 250 Da. Hereby, we report a unique way to obtain red, orange emission in ultrasmall fluorophores (DEAMB, MW = 207 Da), (DEAB, MW = 177 Da), respectively. In this exceptional concept, we explore charge transfer between meta-oriented donor–acceptor moieties in a single-benzenic fluorophore (meta-fluors). Unlike existing red-emitting small-fluorophores, our meta-fluors exhibit an intense Stokes shift (225 nm), solvatochromic shift (175 nm), and excited-state lifetime (21 ns), quite suitable for fluorescence multiplexing. Thus, from size, MW, emission maximum, Stokes shift, solvatochromic shift, excited-state lifetime, etc., points of view meta-fluors are highly advanced in comparison to para-analogues. These two meta-fluors could be employed successfully to image and measure nanopolarity of the perinuclear membrane of live stem cell. These exceptional observations will open up a new branch of developing galaxy of ultrasmall meta-fluors for various applications.

BACKGROUND:Meningiomas are the most common primary central nervous system neoplasms originating from the arachnoid cap cells and constitute between 13% and 26% of all intracranial tumors.AIMS AND OBJECTIVES:The aim of the study was to analyze the age-, sex-, and site-wise distribution of different histological patterns of meningiomas seen in our center and to assess the status of estrogen receptor (ER), progesterone receptor (PR), and proliferation marker Ki-67 in various grades of meningioma.MATERIALS AND METHODS:A prospective study was done in 90 cases. Patients presented with symptoms of headache and seizure and underwent subsequent excision surgery at Neurosurgery Department were taken. We have studied histological typing and grading of the tumors, and immunohistochemical staining was done for ER, PR, and Ki-67.STATISTICAL ANALYSIS:Two-group comparison was done using Mann–Whitney U-test and Fisher's exact test. Comparison of Ki-67 expression between Grade 1 and Grade 2 meningiomas was determined using Mann–Whitney U-test. Comparison of ER and PR status between different histological grades was done by Fisher's exact test. Two-tailed P < 0.001 was considered statistically significant.RESULTS:According to histological type, meningothelial meningioma is most common (38.8%) followed by transitional (22.2%). PR positivity is seen in 96.34% of Grade 1 tumors, and all Grade 2 tumors were PR negative (Fisher's exact test P < 0.001). About 3.66% of Grade 1 and all Grade 2 tumors were positive for ER (Fisher's exact test two-tailed P < 0.001). Mean Ki-67 labeling index (LI) was 2.57 ± 1.674 among Grade I tumors, 7.11 ± 1.084 in Grade II meningiomas.CONCLUSIONS:Most of Grade 1 meningiomas show PRs positivity and lack of ERs positivity. Meningiomas with higher proliferation index and negative PR are very likely to be Grade II or Grade III. Evaluation of ER, PR status, and Ki-67 labeling index (LI) with histological evaluation helps us in providing information about the biologic behavior of meningiomas.

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